IGEN INTERNATIONAL INC /DE
EXHIBIT 10.4
<DOCUMENT>
<TYPE>EX-10
<SEQUENCE>6
<FILENAME>i481050.txt
<DESCRIPTION>EXHIBIT 10.4
<TEXT>
                                                                    Exhibit 10.4


                          REGISTRATION RIGHTS AGREEMENT


                  This Registration Rights Agreement is made and entered into as
of December 7, 2001 (this "AGREEMENT"), by and between IGEN International, Inc.,
a Delaware  corporation  (the  "COMPANY"),  and Acqua  Wellington  Opportunity I
Limited,  a company  organized under the laws of the Commonwealth of the Bahamas
(the "PURCHASER").

                  This  Agreement is being entered into pursuant to the Purchase
Agreement,  dated as of the date  hereof,  by and  between  the  Company and the
Purchaser (the "PURCHASE AGREEMENT").

                  The Company and the Purchaser hereby agree as follows:

         1. DEFINITIONS.

                  Capitalized  terms used and not otherwise defined herein shall
have the meanings  given such terms in the Purchase  Agreement.  As used in this
Agreement, the following terms shall have the following meanings:

                  "AFFILIATE"  means,  with  respect  to any  Person,  any other
Person that directly or indirectly  controls or is controlled by or under common
control with such Person.  For the purposes of this definition,  "CONTROL," when
used with respect to any Person,  means the possession,  direct or indirect,  of
the power to direct or cause the  direction  of the  management  and policies of
such Person, whether through the ownership of voting securities,  by contract or
otherwise;  and the terms  "AFFILIATED,"  "CONTROLLING"  and  "CONTROLLED"  have
meanings correlative to the foregoing.

                  "BLACKOUT  PERIOD" shall have the meaning set forth in Section
3(n).

                  "BOARD" shall have the meaning set forth in Section 3(n).

                  "BUSINESS DAY" means any day except  Saturday,  Sunday and any
day which shall be a legal holiday or a day on which banking institutions in the
state  of New  York  generally  are  authorized  or  required  by  law or  other
government actions to close.

                  "COMMISSION" means the Securities and Exchange Commission.

                  "COMMON  STOCK" means the Company's  Common  Stock,  $.001 par
value.

                  "EFFECTIVENESS  DATE" means with  respect to the  Registration
Statement the earliest of (x) the 105th day  following the Funding Date,  before
which the  Company  will use its  commercially  reasonable  efforts to cause the
registration  statement  to become  effective,  and (y) the date which is within
seven (7) Business Days of the date on which the Commission  informs the Company
that the Commission (i) will not review the Registration  Statement or (ii) that
the  Company  may  request  the   acceleration  of  the   effectiveness  of  the
Registration Statement.

                  "EFFECTIVENESS  PERIOD"  shall have the  meaning  set forth in
Section 2.

<PAGE>

                  "EVENT" shall have the meaning set forth in Section 7(d).

                  "EXCHANGE ACT" means the  Securities  Exchange Act of 1934, as
amended.

                  "FILING  DATE" means the date the  Registration  Statement  is
filed which date, using the Company's commercially  reasonable efforts, shall be
within twenty-one (21) days following the Funding Date.

                  "HOLDER" or "HOLDERS" means the holder or holders, as the case
may be, from time to time of Registrable Securities including, including without
limitation, the Purchaser and its assignees.

                  "INDEMNIFIED  PARTY"  shall  have  the  meaning  set  forth in
Section 5(c).

                  "INDEMNIFYING  PARTY"  shall  have the  meaning  set  forth in
Section 5(c).

                  "LIQUIDATED  DAMAGES"  shall  have the  meaning  set  forth in
Section 7(d).

                  "LOSSES" shall have the meaning set forth in Section 5(a).

                  "PERSON"  means an individual or a  corporation,  partnership,
trust,  incorporated  or  unincorporated  association,  joint  venture,  limited
liability  company,  joint stock company,  government (or an agency or political
subdivision thereof) or other entity of any kind.

                  "PROCEEDING" means an action,  claim,  suit,  investigation or
proceeding   (including,   without  limitation,   an  investigation  or  partial
proceeding, such as a deposition), whether commenced or threatened.

                  "PROSPECTUS" means the prospectus included in the Registration
Statement  (including,  without  limitation,  a  prospectus  that  includes  any
information  previously  omitted from a prospectus filed as part of an effective
registration  statement  in  reliance  upon  Rule  430A  promulgated  under  the
Securities Act), as amended or supplemented by any prospectus  supplement,  with
respect  to  the  terms  of  the  offering  of any  portion  of the  Registrable
Securities covered by the Registration  Statement,  and all other amendments and
supplements to the  Prospectus,  including  post-effective  amendments,  and all
material incorporated by reference in such Prospectus.

                  "REGISTRABLE  SECURITIES"  means the  shares  of Common  Stock
issued  pursuant to the Purchase  Agreement  (the "Common  Shares") and upon any
stock split, stock dividend,  recapitalization  or similar event with respect to
such Common Shares.

                  "REGISTRATION  STATEMENT" means the registration statement and
any additional  registration statements contemplated by Section 2, including (in
each case) the  Prospectus,  amendments  and  supplements  to such  registration
statement or  Prospectus,  including  pre- and  post-effective  amendments,  all
exhibits   thereto,   and  all  material   incorporated  by  reference  in  such
registration statement.



                                      -2-
<PAGE>

                  "RULE  144"  means  Rule  144  promulgated  by the  Commission
pursuant to the  Securities  Act, as such Rule may be amended from time to time,
or any similar rule or regulation  hereafter  adopted by the  Commission  having
substantially the same effect as such Rule.

                  "RULE  158"  means  Rule  158  promulgated  by the  Commission
pursuant to the  Securities  Act, as such Rule may be amended from time to time,
or any similar rule or regulation  hereafter  adopted by the  Commission  having
substantially the same effect as such Rule.

                  "RULE  415"  means  Rule  415  promulgated  by the  Commission
pursuant to the  Securities  Act, as such Rule may be amended from time to time,
or any similar rule or regulation  hereafter  adopted by the  Commission  having
substantially the same effect as such Rule.

                  "SECURITIES ACT" means the Securities Act of 1933, as amended.

                  "SPECIAL COUNSEL" means any special counsel to the Holders.

         2.  REGISTRATION.  On or prior to the  Filing  Date the  Company  shall
prepare and file with the Commission a "shelf"  Registration  Statement covering
all  Registrable  Securities  for an offering to be made on a  continuous  basis
pursuant to Rule 415. The Registration Statement shall be on Form S-3 (except if
the  Company  is not then  eligible  to  register  for  resale  the  Registrable
Securities  on Form S-3,  in which  case such  registration  shall be on another
appropriate form in accordance  herewith).  The Company shall (i) not permit any
securities  other  than  the  Registrable  Securities  to  be  included  in  the
Registration  Statement,  (ii) use its commercially  reasonable efforts to cause
the  Registration  Statement to be declared  effective  under the Securities Act
(including   filing  with  the   Commission  a  request  for   acceleration   of
effectiveness in accordance with Rule 12dl-2  promulgated under the Exchange Act
within seven (7) Business Days of the date that the Company is notified  (orally
or in  writing,  whichever  is earlier) by the  Commission  that a  Registration
Statement will not be  "reviewed," or not be subject to further  review) as soon
as  practicable  after  the  filing  thereof,  but in  any  event  prior  to the
Effectiveness  Date,  and (subject to the  provisions of Section 3(n) hereof) to
keep such Registration Statement continuously effective under the Securities Act
until  such  date  as is the  earlier  of (x)  the  date  when  all  Registrable
Securities covered by such Registration Statement have been sold or (y) the date
on which the Registrable Securities may be sold without any restriction pursuant
to Rule 144(k) as determined by the counsel to the Company pursuant to a written
letter,   addressed  to  the  Company's  transfer  agent  to  such  effect  (the
"EFFECTIVENESS PERIOD").

         3. REGISTRATION PROCEDURES.

                  In  connection  with the  Company's  registration  obligations
hereunder, the Company shall:

                  (a)  Prepare  and  file  with  the   Commission   as  soon  as
practicable  and in any event on or prior to the  Filing  Date,  a  Registration
Statement  on Form S-3 (or if the Company is not then  eligible to register  for
resale the  Registrable  Securities  on Form S-3 such  registration  shall be on
another  appropriate form in accordance  herewith) in accordance with the method
or  methods  of  distribution  thereof as  specified  by the  Holder  (except if
subsequently  otherwise  directed  by the  Holder),  and  use  its  commercially
reasonable  efforts to cause the Registration  Statement to become effective and


                                      -3-
<PAGE>

remain effective as provided herein; PROVIDED, HOWEVER, that not less than three
(3)  Business  Days prior to the  filing of the  Registration  Statement  or any
related  Prospectus  or any  amendment  or  supplement  thereto  (including  any
document that would be  incorporated  therein by  reference),  the Company shall
furnish to the  Holder and any  Special  Counsel,  copies of all such  documents
proposed  to be  filed,  which  documents  (other  than  those  incorporated  by
reference)  will be subject to the timely  review of such Special  Counsel.  The
Company shall not file the Registration  Statement or any such Prospectus or any
amendments or supplements  thereto relating to the Purchaser or the transactions
contemplated  hereby to which the Holder or any Special Counsel shall reasonably
object in writing  within  three (3)  Business  Days of their  receipt  thereof;
provided,  however,  that if  Special  Counsel  does  not  respond  within  such
three-day period, the Company shall not incur any liquidated damages pursuant to
Section 7(d)(i) hereof for the time period of such delay.

                  (b) (i) Prepare and file with the Commission such  amendments,
including  post-effective  amendments,  to the Registration  Statement as may be
necessary to keep the Registration  Statement continuously effective (subject to
Section  3(n)  hereof)  as to the  applicable  Registrable  Securities  for  the
Effectiveness  Period and prepare and file with the Commission  such  additional
Registration Statements in order to register for resale under the Securities Act
all of the  Registrable  Securities;  (ii) cause the  related  Prospectus  to be
amended  or  supplemented  by  any  required  Prospectus  supplement,  and as so
supplemented  or  amended  to be  filed  pursuant  to Rule  424 (or any  similar
provisions  then in force)  promulgated  under the Securities Act; (iii) respond
promptly  to any  comments  received  from the  Commission  with  respect to the
Registration Statement or any amendment thereto and promptly provide the Holders
true and complete copies of all correspondence  from the Commission  relating to
the Registration  Statement;  and (iv) comply in all material  respects with the
provisions  of the  Securities  Act and the  Exchange  Act with  respect  to the
disposition of all Registrable  Securities covered by the Registration Statement
during  the  applicable  period  in  accordance  with the  intended  methods  of
disposition by the Holders thereof set forth in the Registration Statement as so
amended or in such Prospectus as so supplemented.

                  (c) Notify the Holders of  Registrable  Securities  to be sold
and any Special  Counsel  promptly  (and, in the case of (i)(A) below,  not less
than three (3) Business Days prior to such filing) and (if requested by any such
Person)  confirm  such notice in writing no later than three (3)  Business  Days
following  the day (i)(A) when a  Prospectus  or any  Prospectus  supplement  or
post-effective  amendment to the Registration Statement is proposed to be filed;
(B) when the Commission notifies the Company whether there will be a "review" of
such Registration  Statement and whenever the Commission  comments in writing on
such Registration  Statement and (C) with respect to the Registration  Statement
or any  post-effective  amendment  relating to the Purchaser or the transactions
contemplated hereby, when the same has become effective; provided, however, that
if Special  Counsel does not respond within such time period,  the Company shall
not incur any liquidated damages pursuant to Section 7(d)(i) hereof for the time
period of such delay; (ii) of any request by the Commission or any other Federal
or  state   governmental   authority  for   amendments  or  supplements  to  the
Registration Statement or Prospectus or for additional information; (iii) of the
issuance by the Commission of any stop order suspending the effectiveness of the
Registration  Statement covering any or all of the Registrable Securities or the
initiation  of any  Proceedings  for that  purpose;  (iv) of the  receipt by the
Company of any notification  with respect to the suspension of the qualification
or exemption from qualification of any of the Registrable Securities for sale in


                                      -4-
<PAGE>

any  jurisdiction,  or the  initiation or threatening of any Proceeding for such
purpose; and (v) of the occurrence of any event that makes any statement made in
the Registration  Statement or Prospectus or any document incorporated or deemed
to be incorporated  therein by reference  untrue in any material respect or that
requires  any  revisions  to the  Registration  Statement,  Prospectus  or other
documents so that, in the case of the Registration  Statement or the Prospectus,
as the case may be, it will not contain any untrue  statement of a material fact
or omit to state any material fact required to be stated therein or necessary to
make the statements  therein, in the light of the circumstances under which they
were made, not misleading.

                  The Company shall promptly furnish to Special Counsel, without
charge, any correspondence  from the Commission or the Commission's staff to the
Company or its representatives relating to any Registration Statement.

                  (d) Use its  commercially  reasonable  efforts  to  avoid  the
issuance of, or, if issued,  obtain the withdrawal of, (i) any order  suspending
the  effectiveness of the  Registration  Statement or (ii) any suspension of the
qualification  (or  exemption  from  qualification)  of any  of the  Registrable
Securities for sale in any jurisdiction, at the earliest practicable moment.

                  (e) If  requested  by the Holder of a majority  in interest of
the Registrable Securities,  (i) promptly incorporate in a Prospectus supplement
or  post-effective  amendment to the Registration  Statement such information as
the  Company  reasonably  agrees  should be  included  therein and (ii) make all
required filings of such Prospectus supplement or such post-effective  amendment
as soon as  practicable  after the  Company  has  received  notification  of the
matters to be  incorporated  in such  Prospectus  supplement  or  post-effective
amendment.

                  (f)  Furnish to the Holder and any  Special  Counsel,  without
charge,  at least one  conformed  copy of each  Registration  Statement and each
amendment thereto,  including financial statements and schedules,  all documents
incorporated or deemed to be incorporated therein by reference, and all exhibits
to the extent requested by such Person (including those previously  furnished or
incorporated by reference)  promptly after the filing of such documents with the
Commission.

                  (g)  Promptly  deliver to the Holder and any Special  Counsel,
without  charge,  as many copies of the  Registration  Statement,  Prospectus or
Prospectuses   (including  each  form  of  prospectus)  and  each  amendment  or
supplement  thereto as such  Persons  may  reasonably  request;  and the Company
hereby  consents to the use of such  Prospectus and each amendment or supplement
thereto by each of the selling  Holders in connection with the offering and sale
of the  Registrable  Securities  covered by such Prospectus and any amendment or
supplement thereto.

                  (h) Prior to any public  offering of  Registrable  Securities,
use its commercially reasonable efforts to register or qualify or cooperate with
the selling Holders and any Special Counsel in connection with the  registration
or qualification  (or exemption from such registration or qualification) of such
Registrable  Securities for offer and sale under the securities or Blue Sky laws
of such jurisdictions within the United States as any Holder reasonably requests
in  writing,  to keep each such  registration  or  qualification  (or  exemption
therefrom)  effective during the  Effectiveness  Period (subject to Section 3(n)
hereof) and to do any and all other acts or things  necessary  or  advisable  to


                                      -5-
<PAGE>

enable the  disposition  in such  jurisdictions  of the  Registrable  Securities
covered by a Registration Statement;  PROVIDED,  HOWEVER, that the Company shall
not be required to qualify generally to do business in any jurisdiction where it
is not then so qualified or to take any action that would  subject it to general
service of process in any such  jurisdiction  where it is not then so subject or
subject the Company to any material tax in any such jurisdiction where it is not
then so subject.

                  (i)  Cooperate  with the  Holders  to  facilitate  the  timely
preparation  and delivery of certificates  or via the Deposit  Withdrawal  Agent
Commission ("DWAC") representing Registrable Securities to be sold pursuant to a
Registration  Statement and to enable such Registrable  Securities to be in such
denominations  and  registered in such names as the Holders may request at least
two (2) Business Days prior to any sale of Registrable Securities.

                  (j) Upon the occurrence of any event  contemplated  by Section
3(c)(v), as promptly as possible, prepare a supplement or amendment, including a
post-effective  amendment,  to the Registration Statement or a supplement to the
related  Prospectus or any document  incorporated  or deemed to be  incorporated
therein  by  reference,  and file  any  other  required  document  so  that,  as
thereafter  delivered,  neither the  Registration  Statement nor such Prospectus
will contain an untrue  statement of a material fact or omit to state a material
fact required to be stated therein or necessary to make the statements  therein,
in the light of the circumstances under which they were made, not misleading.

                  (k) Use its  commercially  reasonable  efforts  to  cause  all
Registrable  Securities relating to such Registration  Statement to be listed on
the Nasdaq National Market and any other securities exchange,  quotation system,
market or  over-the-counter  bulletin board, if any, on which similar securities
issued by the  Company  are then  listed as and when  required  pursuant  to the
Purchase Agreement.

                  (l) Comply in all material  respects with all applicable rules
and  regulations of the Commission and make generally  available to its security
holders  earning  statements  satisfying  the provisions of Section 11(a) of the
Securities Act and Rule 158 not later than forty-five (45) days after the end of
any twelve  (12)-month  period (or ninety  (90) days after the end of any twelve
(12)-month  period if such period is a fiscal year)  commencing on the first day
of the first  fiscal  quarter of the  Company  after the  effective  date of the
Registration  Statement,  which statement  shall conform to the  requirements of
Rule 158.

                  (m) If the Registration Statement refers to any Holder by name
or otherwise as the holder of any  securities  of the Company,  then such Holder
shall have the right to require  (if such  reference  to such  Holder by name or
otherwise is not required by the Securities Act or any similar  federal  statute
then in force) the deletion of the  reference to such Holder in any amendment or
supplement to the  Registration  Statement  filed or prepared  subsequent to the
time that such reference ceases to be required.

                  (n) Each Holder covenants and agrees that (i) it will not sell
any  Registrable  Securities  under  the  Registration  Statement  until  it has
received   copies  of  the  Prospectus  as  then  amended  or   supplemented  as
contemplated in Section 3(g) and notice from the Company that such  Registration
Statement and any  post-effective  amendments  thereto have become  effective as


                                      -6-
<PAGE>

contemplated by Section 3(c), (ii) it and its officers, directors or Affiliates,
if any, will comply with the prospectus delivery  requirements of the Securities
Act as  applicable to them in connection  with sales of  Registrable  Securities
pursuant to the  Registration  Statement,  (iii) it shall  comply  with  federal
securities laws and (iv) it shall furnish to the Company  information  regarding
such Holder and the distribution of such  Registrable  Securities as is required
by law to be  disclosed  in the  Registration  Statement,  and the  Company  may
exclude from such registration the Registrable Securities of any such Holder who
fails to furnish such  information  within a reasonable time prior to the filing
of  each  Registration   Statement,   supplemented   Prospectus  and/or  amended
Registration Statement.

                  Each  Holder  agrees by its  acquisition  of such  Registrable
Securities  that, upon receipt of a notice from the Company of the occurrence of
any  event of the kind  described  in  Section  3(c)(ii),  3(c)(iii),  3(c)(iv),
3(c)(v), 3(c)(vi) or 3(n), such Holder will forthwith discontinue disposition of
such Registrable Securities under the Registration Statement until such Holder's
receipt of the copies of the supplemented Prospectus and/or amended Registration
Statement  contemplated  by Section 3(j), or until it is advised in writing (the
"ADVICE")  by the  Company  that  the use of the  applicable  Prospectus  may be
resumed,  and,  in  either  case,  has  received  copies  of any  additional  or
supplemental  filings  that are  incorporated  or deemed to be  incorporated  by
reference in such Prospectus or Registration Statement.

                  (o) If (i) there is material non-public  information regarding
the Company which the  Company's  Board of Directors  (the  "BOARD")  reasonably
determines  not to be in the  Company's  best interest to disclose and which the
Company is not  otherwise  required to disclose,  or (ii) there is a significant
business  opportunity  (including,  but  not  limited  to,  the  acquisition  or
disposition  of assets  (other than in the  ordinary  course of business) or any
merger,  consolidation,  tender offer or other similar transaction) available to
the Company  which the Board  reasonably  determines  not to be in the Company's
best  interest to disclose  and which the Company  would be required to disclose
under the Registration Statement,  then the Company may suspend effectiveness of
a registration  statement and suspend the sale of Registrable Securities under a
Registration  Statement for a period not to exceed twenty (20) consecutive days,
provided  that the  Company  may not  suspend  its  obligation  pursuant to this
Section  3(n) for more than  forty-five  (45) days in the  aggregate  during any
twelve (12) month period (each, a "BLACKOUT PERIOD"); PROVIDED, HOWEVER, that no
such  suspension  shall be permitted  for  consecutive  twenty (20) day periods,
arising out of the same set of facts, circumstances or transactions.

                  (p)  Within  two (2)  Business  Days  after  the  Registration
Statement which includes the Registrable  Securities is ordered effective by the
Commission,  the Company  shall  deliver,  and shall cause legal counsel for the
Company to deliver, to the transfer agent for such Registrable  Securities (with
copies  to the  Holders  whose  Registrable  Securities  are  included  in  such
Registration  Statement)  confirmation that the Registration  Statement has been
declared effective by the Commission in the form attached hereto as EXHIBIT A.

         4. REGISTRATION EXPENSES.

                  All reasonable  fees and expenses  incident to the performance
of or  compliance  with  this  Agreement  by the  Company  shall be borne by the
Company whether or not the Registration  Statement is filed or becomes effective
and  whether  or  not  any  Registrable  Securities  are  sold  pursuant  to the


                                      -7-
<PAGE>

Registration  Statement.  The fees and  expenses  referred  to in the  foregoing
sentence shall include,  without limitation the following:  (i) all registration
and filing fees  (including,  without  limitation,  fees and  expenses  (A) with
respect to filings  required to be made with the Nasdaq National Market and each
other securities exchange or market on which Registrable Securities are required
hereunder to be listed, (B) with respect to filings required to be made with the
Commission,  and (C) in compliance with state securities or Blue Sky laws), (ii)
printing  expenses   (including,   without  limitation,   expenses  of  printing
certificates  for  Registrable  Securities and of printing  prospectuses  if the
printing  of  prospectuses  is  requested  by the  holders of a majority  of the
Registrable Securities included in the Registration Statement), (iii) messenger,
telephone and delivery expenses,  (iv) fees and disbursements of counsel for the
Company and (v) fees and expenses of all other  Persons  retained by the Company
in connection  with the  consummation of the  transactions  contemplated by this
Agreement,  including,  without  limitation,  the Company's  independent  public
accountants  (including the expenses of any comfort letters or costs  associated
with the  delivery by  independent  public  accountants  of a comfort  letter or
comfort letters).  In addition,  the Company shall be responsible for all of its
internal   expenses   incurred  in  connection  with  the  consummation  of  the
transactions contemplated by this Agreement (including,  without limitation, all
salaries  and  expenses  of its  officers  and  employees  performing  legal  or
accounting  duties),  the  expense of any annual  audit,  the fees and  expenses
incurred in  connection  with the listing of the  Registrable  Securities on any
securities exchange as required hereunder.  The Company shall not be responsible
for any underwriting discounts and commissions, transfer taxes or the legal fees
of Special Counsel.

         5. INDEMNIFICATION

                  (a)  INDEMNIFICATION  BY  THE  COMPANY.   The  Company  shall,
notwithstanding  any termination of this Agreement,  indemnify and hold harmless
the Purchaser, its permitted assignees and each of its directors, fund managers,
officers and employees,  and each Person who controls any such Purchaser (within
the meaning of Section 15 of the  Securities  Act or Section 20 of the  Exchange
Act),  its permitted  assignees and the directors,  fund managers,  officers and
employees  of each  such  controlling  Person,  and the  respective  successors,
assigns,  estate and personal  representatives of each of the foregoing,  to the
fullest extent permitted by applicable law, from and against any and all claims,
losses, damages, liabilities,  penalties,  judgments, costs (including,  without
limitation, costs of investigation) and expenses (including, without limitation,
reasonable attorneys' fees and expenses) (collectively,  "LOSSES"),  arising out
of or  relating to any untrue or alleged  untrue  statement  of a material  fact
contained in the Registration Statement,  the final Prospectus,  as supplemented
or amended,  if  applicable,  or arising  out of or relating to any  omission or
alleged  omission of a material fact required to be stated  therein or necessary
to make  the  statements  therein  (in the  case  of any  Prospectus  or form of
prospectus or supplement  thereto, in the light of the circumstances under which
they were made) not  misleading,  except to the extent,  but only to the extent,
that such untrue  statements  or  omissions  are based  solely upon  information
regarding  such  Holder  furnished  in  writing to the  Company  by such  Holder
expressly for use therein, which information was reviewed and expressly approved
in  writing  by  such  Holder  and  Special  Counsel  expressly  for  use in the
Registration  Statement,  such  Prospectus  or such form of Prospectus or in any
amendment or  supplement  thereto or as a result of the failure of the Holder to
deliver a Prospectus,  as amended or supplemented,  to a purchaser in connection
with an offer or sale.  The Company  shall  notify the  Holders  promptly of the
institution, threat or assertion of any Proceeding of which the Company is aware
in  connection  with  the  transactions  contemplated  by this  Agreement.  Such


                                      -8-
<PAGE>

indemnity shall remain in full force and effect  regardless of any investigation
made by or on behalf of an Indemnified Party (as defined in Section 5(c) hereof)
and shall survive the transfer of the Registrable Securities by the Holders.

                  (b) INDEMNIFICATION BY PURCHASER.  Purchaser and its permitted
assignees  shall,  severally  and not jointly,  indemnify  and hold harmless the
Company,  each of its  directors,  officers  and  employees  and each Person who
controls the Company (within the meaning of Section 15 of the Securities Act and
Section 20 of the Exchange Act),  and the  directors,  officers and employees of
such controlling Persons,  and the respective  successors,  assigns,  estate and
personal  representatives  of  each  of the  foregoing,  to the  fullest  extent
permitted by applicable law, from and against all Losses,  as incurred,  arising
solely out of or based  solely  upon  failure of the  Purchaser  to deliver  the
prospectus when required or any untrue statement of a material fact contained in
the  Registration  Statement,  any  Prospectus,  or any form of  prospectus,  or
arising  solely out of or based  solely  upon any  omission  of a material  fact
required to be stated  therein or necessary to make the  statements  therein (in
the case of any Prospectus or form of prospectus or supplement  thereto,  in the
light of the  circumstances  under which they were made) not misleading,  to the
extent,  but only to the  extent,  that such  untrue  statement  or  omission is
contained  in or omitted  from any  information  so furnished in writing by such
Holder or the Special Counsel to the Company  specifically  for inclusion in the
Registration  Statement  or  such  Prospectus  and  that  such  information  was
reasonably  relied upon by the Company  for use in the  Registration  Statement,
such  Prospectus  or  such  form  of  prospectus  or to  the  extent  that  such
information  relates  to  such  Holder  or  such  Holder's  proposed  method  of
distribution of Registrable  Securities and was reviewed and expressly  approved
in writing by such Holder expressly for use in the Registration Statement,  such
Prospectus or such form of Prospectus  Supplement.  Notwithstanding  anything to
the  contrary  contained  herein,  the Holder shall be liable under this Section
5(b) for only that amount as does not exceed the net  proceeds to such Holder as
a result of the sale of  Registrable  Securities  pursuant to such  Registration
Statement.

                  (c) CONDUCT OF INDEMNIFICATION  PROCEEDINGS. If any Proceeding
shall be brought or asserted against any Person entitled to indemnity  hereunder
(an  "INDEMNIFIED  PARTY"),  such  Indemnified  Party  promptly shall notify the
Person from whom indemnity is sought (the "INDEMNIFYING  PARTY) in writing,  and
the  Indemnifying  Party  shall  assume  the  defense  thereof,   including  the
employment of counsel  reasonably  satisfactory to the Indemnified Party and the
payment of all fees and expenses  incurred in connection  with defense  thereof;
provided,  that the failure of any  Indemnified  Party to give such notice shall
not relieve the Indemnifying Party of its obligations or liabilities pursuant to
this  Agreement,  except  (and  only) to the  extent  that it  shall be  finally
determined  by a court of competent  jurisdiction  (which  determination  is not
subject to appeal or further review) that such failure shall have materially and
adversely prejudiced the Indemnifying Party.

                  An Indemnified  Party shall have the right to employ  separate
counsel in any such  Proceeding and to participate in the defense  thereof,  but
the  fees  and  expenses  of  such  counsel  shall  be at the  expense  of  such
Indemnified  Party or Parties unless:  (1) the Indemnifying  Party has agreed in
writing to pay such fees and expenses;  or (2) the Indemnifying Party shall have
failed  promptly to assume the defense of such  Proceeding and to employ counsel
reasonably satisfactory to such Indemnified Party in any such Proceeding; or (3)
the named  parties to any such  Proceeding  (including  any  impleaded  parties)


                                      -9-
<PAGE>

include  both  such  Indemnified  Party  and the  Indemnifying  Party,  and such
Indemnified Party shall have been advised by counsel that a conflict of interest
is likely to exist if the same counsel were to represent such Indemnified  Party
and the Indemnifying  Party (in which case, if such  Indemnified  Party notifies
the  Indemnifying  Party in writing that it elects to employ separate counsel at
the expense of the Indemnifying Party, the Indemnifying Party shall not have the
right to assume the defense  thereof and such counsel shall be at the expense of
the  Indemnifying  Party).  The  Indemnifying  Party shall not be liable for any
settlement of any such Proceeding  effected without its written  consent,  which
consent shall not be unreasonably withheld. No Indemnifying Party shall, without
the prior written consent of the Indemnified Party, effect any settlement of any
pending Proceeding in respect of which any Indemnified Party is a party,  unless
such settlement includes an unconditional release of such Indemnified Party from
all liability on claims that are the subject matter of such Proceeding.

                  All  reasonable  fees and  expenses of the  Indemnified  Party
(including  reasonable  fees and expenses to the extent  incurred in  connection
with  investigating  or  preparing  to defend  such  Proceeding  in a manner not
inconsistent  with this  Section)  shall be paid to the  Indemnified  Party,  as
incurred,  within  twenty (20) Business  Days of written  notice  thereof to the
Indemnifying  Party  (regardless of whether it is ultimately  determined that an
Indemnified Party is not entitled to indemnification  hereunder;  PROVIDED, that
the  Indemnifying  Party may require  such  Indemnified  Party to  undertake  to
reimburse  all such fees and  expenses  to the extent it is  finally  judicially
determined  that  such  Indemnified  Party is not  entitled  to  indemnification
hereunder or pursuant to applicable law).

                  (d) CONTRIBUTION. If a claim for indemnification under Section
5(a) or 5(b) is  unavailable  to an  Indemnified  Party  because of a failure or
refusal  of  a  governmental   authority  to  enforce  such  indemnification  in
accordance  with its terms (by reason of public policy or otherwise),  then each
Indemnifying  Party,  in lieu of  indemnifying  such  Indemnified  Party,  shall
contribute to the amount paid or payable by such  Indemnified  Party as a result
of such Losses,  in such  proportion as is  appropriate  to reflect the relative
fault of the  Indemnifying  Party and  Indemnified  Party in connection with the
actions,  statements  or omissions  that  resulted in such Losses as well as any
other relevant equitable considerations. The relative fault of such Indemnifying
Party and  Indemnified  Party shall be  determined  by reference to, among other
things,  whether any action in question,  including any untrue or alleged untrue
statement of a material fact or omission or alleged omission of a material fact,
has been  taken  or made  by,  or  relates  to  information  supplied  by,  such
Indemnifying  Party or  Indemnified  Party,  and the parties'  relative  intent,
knowledge,  access to  information  and  opportunity  to correct or prevent such
action, statement or omission. The amount paid or payable by a party as a result
of any Losses shall be deemed to include,  subject to the  limitations set forth
in Section 5(c), any reasonable  attorneys' or other reasonable fees or expenses
incurred  by such party in  connection  with any  Proceeding  to the extent such
party   would  have  been   indemnified   for  such  fees  or  expenses  if  the
indemnification  provided  for in this  Section was  available  to such party in
accordance with its terms.  Notwithstanding  anything to the contrary  contained
herein,  the Holder shall be liable or required to contribute under this Section
5(c) for only that amount as does not exceed the net  proceeds to such Holder as
a result of the sale of  Registrable  Securities  pursuant to such  Registration
Statement.



                                      -10-
<PAGE>

                  The  parties  hereto  agree  that it  would  not be  just  and
equitable if  contribution  pursuant to this Section 5(d) were determined by pro
rata  allocation  or by any other method of  allocation  that does not take into
account the equitable  considerations  referred to in the immediately  preceding
paragraph. No Person guilty of fraudulent  misrepresentation (within the meaning
of Section 11(f) of the Securities Act) shall be entitled to  contribution  from
any Person who was not guilty of such fraudulent misrepresentation.

                  The indemnity and  contribution  agreements  contained in this
Section are in addition to any liability that the Indemnifying  Parties may have
to the Indemnified Parties.

         6. RULE 144.

                  As long as any Holder owns Registrable Securities, the Company
covenants  to timely  file (or obtain  extensions  in respect  thereof  and file
within the  applicable  grace  period) all  reports  required to be filed by the
Company after the date hereof pursuant to Section 13(a) or 15(d) of the Exchange
Act and (only if such filings are not available  via EDGAR) to promptly  furnish
the Holders with true and complete  copies of all such  filings.  As long as any
Holder  owns  Registrable  Securities,  if the  Company is not  required to file
reports  pursuant to Section 13(a) or 15(d) of the Exchange Act, it will prepare
and furnish to the Holders and make publicly  available in accordance  with Rule
144(c)  promulgated  under the  Securities  Act annual and  quarterly  financial
statements, together with a discussion and analysis of such financial statements
in form and  substance  substantially  similar to those that would  otherwise be
required  to be included  in reports  required by Section  13(a) or 15(d) of the
Exchange Act, as well as any other  information  required  thereby,  in the time
period that such  filings  would have been  required to have been made under the
Exchange  Act.  The Company  further  covenants  that it will take such  further
action as any Holder may  reasonably  request,  all to the extent  required from
time to time to  enable  such  Person  to sell  Registrable  Securities  without
registration  under the  Securities  Act within the limitation of the exemptions
provided by Rule 144 promulgated under the Securities Act,  including  providing
any legal  opinions  of  counsel  to the  Company  referred  to in the  Purchase
Agreement.  Upon the request of any Holder,  the Company  shall  deliver to such
Holder a written certification of a duly authorized officer as to whether it has
complied with such  requirements.  This Agreement shall terminate on the date on
which the  Registrable  Securities  have been sold  pursuant  to a  registration
statement  or may be sold  without  restriction  pursuant  to Rule 144(k) of the
Securities Act.

         7. MISCELLANEOUS.

                  (a) REMEDIES.  In the event of a breach by the Company or by a
Holder,  of any of their  obligations  under this Agreement,  each Holder or the
Company,  as the case may be, in  addition to being  entitled  to  exercise  all
rights granted by law and under this Agreement,  including  recovery of damages,
will be entitled to specific performance of its rights under this Agreement. The
Company and each Holder agree that monetary  damages would not provide  adequate
compensation  for any losses  incurred by reason of a breach by it of any of the
provisions of this Agreement and hereby further agrees that, in the event of any
action for specific  performance  in respect of such breach,  it shall waive the
defense that a remedy at law would be adequate.



                                      -11-
<PAGE>

                  (b) NO INCONSISTENT AGREEMENTS. Neither the Company nor any of
its  subsidiaries  has,  as of the date hereof  entered  into and  currently  in
effect, nor shall the Company or any of its Affiliates,  on or after the date of
this Agreement,  enter into any agreement with respect to its securities that is
inconsistent  with the  rights  granted  to the  Holders  in this  Agreement  or
otherwise conflicts with the provisions hereof.  Without limiting the generality
of the  foregoing,  without the written  consent of the Holders of a majority of
the then outstanding Registrable Securities,  the Company shall not grant to any
Person the right to  request  the  Company to  register  any  securities  of the
Company under the Securities Act if the rights so granted are inconsistent  with
the rights granted to Holders set forth herein, or otherwise prevent the Company
with complying with all of its obligations hereunder.

                  (c) NO PIGGYBACK ON REGISTRATIONS. Neither the Company nor any
of its  security  holders  (other  than the  Holders in such  capacity  pursuant
hereto) may include securities of the Company in the Registration Statement.

                  (d) FAILURE TO FILE  REGISTRATION  STATEMENT AND OTHER EVENTS.
The Company and the Holders  agree that the Holders  will suffer  damages if the
Registration  Statement  is not  filed on or prior  to the  Filing  Date and not
declared  effective by the Commission on or prior to the Effectiveness  Date and
maintained in the manner contemplated herein during the Effectiveness  Period or
if certain other events occur. The Company and the Holders further agree that it
would not be feasible to ascertain  the extent of such  damages with  precision.
Accordingly,  if (i) the Registration  Statement is not filed on or prior to the
Filing Date, or is not declared  effective by the  Commission on or prior to the
Effectiveness  Date,  or (ii) the Company  fails to file with the  Commission  a
request for  acceleration in accordance with Rule 12dl-2  promulgated  under the
Exchange  Act within  seven (7)  Business  Days of the date that the  Company is
notified  (orally or in writing,  whichever is earlier) by the Commission that a
Registration Statement will not be "reviewed," or not subject to further review,
or (iii) the Registration  Statement is filed with and declared effective by the
Commission  but  thereafter  ceases  to  be  effective  as  to  all  Registrable
Securities at any time during the Effectiveness Period,  without being succeeded
within a reasonable period by a subsequent Registration Statement filed with and
declared  effective by the Commission,  or (iv) the Company has breached Section
3(n) of this  Agreement  (any such  failure or breach  being  referred  to as an
"EVENT"),  the Company shall pay as liquidated  damages for such failure and not
as a penalty  (the  "LIQUIDATED  DAMAGES") to each Holder an amount equal to one
percent  (1%) for the first  calendar  month and two percent  (2%) per  calendar
month  thereafter of such Holder's pro rata share of the purchase  price paid by
all  Holders  for all shares of Common  Shares  purchased  and then  outstanding
pursuant to the Purchase  Agreement for each thirty (30) day period,  or portion
thereof, following the Event until the applicable Event has been cured. Payments
to be made  pursuant to this Section  7(d) shall be due and payable  immediately
upon  demand at the option of the Holders in cash.  The  parties  agree that the
Liquidated  Damages represent a reasonable  estimate on the part of the parties,
as of the date of this Agreement,  of the amount of damages that may be incurred
by the  Holders if the  Registration  Statement  is not filed on or prior to the
Filing Date or has not been declared  effective by the Commission on or prior to
the Effectiveness Date and maintained in the manner  contemplated  herein during
the Effectiveness Period or if any other Event as described herein has occurred.



                                      -12-
<PAGE>

                  (e) SPECIFIC ENFORCEMENT, CONSENT TO JURISDICTION.

                         (i) The Company and the Holders  acknowledge  and agree
that  irreparable  damage would occur in the event that any of the provisions of
this Agreement or the Purchase  Agreement were not performed in accordance  with
their specific terms or were otherwise  breached.  It is accordingly agreed that
the parties shall be entitled to an injunction or injunctions to prevent or cure
breaches of the  provisions of this  Agreement or the Purchase  Agreement and to
enforce  specifically the terms and provisions hereof or thereof,  this being in
addition  to any other  remedy to which  any of them may be  entitled  by law or
equity.

                         (ii) Both the  Company  and the  Purchaser  (i)  hereby
irrevocably  submit to the  jurisdiction of the United States District Court for
the  Southern  District  of New York  and the  courts  of the  State of New York
located in New York county for the  purposes of any suit,  action or  proceeding
arising out of or relating to this  Agreement and (ii) hereby  waive,  and agree
not to assert in any such suit,  action or proceeding,  any claim that it is not
personally  subject to the jurisdiction of such court,  that the suit, action or
proceeding  is brought in an  inconvenient  forum or that the venue of the suit,
action or proceeding is improper.  Both the Company and the Purchaser consent to
process  being served in any such suit,  action or  proceeding by mailing a copy
thereof  to such party at the  address  in effect  for  notices to it under this
Agreement  and agrees that such service  shall  constitute  good and  sufficient
service of process and notice thereof. Nothing in this Section 7(e) shall affect
or limit any right to serve process in any other manner permitted by law.

                  (f) AMENDMENTS AND WAIVERS.  The provisions of this Agreement,
including  the  provisions  of this  sentence,  may not be amended,  modified or
supplemented,  and waivers or consents to departures from the provisions  hereof
may not be given,  unless the same shall be in writing and signed by the Company
and a majority of the Holders.

                  (g) NOTICES.  Any and all notices or other  communications  or
deliveries  required or permitted to be provided  hereunder  shall be in writing
and  shall be deemed  given  and  effective  on the  earlier  of (i) the date of
transmission,  if such notice or communication is delivered via facsimile at the
facsimile  telephone  number  specified  for notice prior to 5:00 p.m.,  eastern
standard  time,  on a  Business  Day,  (ii) the  Business  Day after the date of
transmission,  if such notice or communication is delivered via facsimile at the
facsimile  telephone number  specified for notice later than 5:00 p.m.,  eastern
time, on any date and earlier than 11:59 p.m., eastern time, on such date, (iii)
the Business Day following the date of mailing, if sent by nationally recognized
overnight  courier  service  or (iv)  actual  receipt  by the party to whom such
notice is required to be given.

                           (x)      if to the Company:

                                    IGEN International, Inc.
                                    16020 Industrial Drive
                                    Gaithersburg, MD 20877
                                    Tel. No.:  (301) 869-9800
                                    Fax No.:  (301) 208-3799
                                    Attention: Richard Massey



                                      -13-
<PAGE>

                                    with a copy to:

                                    Kirkpatrick & Lockhart LLP
                                    1800 Massachusetts Avenue, N.W.
                                    Suite 200
                                    Washington, D.C. 20036
                                    Tel. No.:  (202) 778-9076
                                    Fax No.:  (202) 778-9100
                                    Attention: Thomas F. Cooney, III

                           (y)   if to the Purchaser:

                                    Acqua Wellington Opportunity I Limited
                                    Shirlaw House
                                    87 Shirley Street
                                    P.O. Box SS-19084
                                    Nassau, Bahamas
                                    Attention: Michael Taylor
                                    Fax No.: (242) 328-6919

                                    with a copy to:

                                    Jenkens & Gilchrist Parker Chapin LLP
                                    The Chrysler Building
                                    405 Lexington Avenue
                                    New York, New York 10174
                                    Attention:  Christopher S. Auguste
                                    Tel. No.: (212) 704-6000
                                    Fax No.: (212) 704-6288

or to such other address or addresses or facsimile number or numbers as any such
party may most recently have  designated in writing to the other parties  hereto
by such notice.  Any notice sent by facsimile  shall be confirmed by other means
pursuant to this Section 7(g).

                  (h)  SUCCESSORS AND ASSIGNS.  This Agreement  shall be binding
upon and inure to the benefit of the parties and their  successors and permitted
assigns and shall inure to the  benefit of each  Holder and its  successors  and
assigns.  The  Company  may not assign  this  Agreement  or any of its rights or
obligations  hereunder  without  the prior  written  consent  of a  majority  of
Holders.

                  (i)  ASSIGNMENT  OF  REGISTRATION  RIGHTS.  The rights of each
Holder  hereunder,  including the right to have the Company  register for resale
Registrable Securities in accordance with the terms of this Agreement,  shall be
assignable  by each Holder to any  transferee of such Holder of all or a portion
of the shares of  Registrable  Securities  if: (i) the Holder  agrees in writing
with the  transferee  or  assignee  to assign  such  rights,  and a copy of such
agreement  is  furnished  to the  Company  within a  reasonable  time after such
assignment, (ii) the Company is, within a reasonable time after such transfer or


                                      -14-
<PAGE>

assignment,  furnished  with written  notice of (a) the name and address of such
transferee  or  assignee,  and (b) the  securities  with  respect  to which such
registration  rights are being  transferred  or assigned,  (iii)  following such
transfer  or  assignment  the  further  disposition  of such  securities  by the
transferee or assignees is restricted  under the  Securities  Act and applicable
state  securities  laws,  (iv) at or before the time the  Company  receives  the
written notice  contemplated  by clause (ii) of this Section,  the transferee or
assignee agrees in writing with the Company to be bound by all of the provisions
of this Agreement, and (v) such transfer shall have been made in accordance with
the applicable  requirements of the Purchase  Agreement and shall be for no less
than 50% of the Registrable Securities.  In addition, each Holder shall have the
right to  assign  its  rights  hereunder  to any  other  Person  so long as such
assignment is for no less than 30% of the Registrable  Securities with the prior
written  consent  of the  Company,  which  consent  shall  not  be  unreasonably
withheld.  The  rights  to  assignment  shall  apply  to  the  Holders  (and  to
subsequent) successors and assigns.

                  (j) COUNTERPARTS. This Agreement may be executed in any number
of  counterparts,  each of  which  when so  executed  shall be  deemed  to be an
original  and, all of which taken  together  shall  constitute  one and the same
Agreement.   In  the  event  that  any   signature  is  delivered  by  facsimile
transmission,  such  signature  shall create a valid  binding  obligation of the
party  executing  (or on whose behalf such  signature is executed) the same with
the same  force and  effect as if such  facsimile  signature  were the  original
thereof.

                  (k)  GOVERNING  LAW. This  Agreement  shall be governed by and
construed in accordance  with the laws of the State of New York,  without regard
to  principles  of  conflicts  of  law  thereof.  This  Agreement  shall  not be
interpreted  or construed  with any  presumption  against the party causing this
Agreement to be drafted.

                  (l)  CUMULATIVE  REMEDIES.  The remedies  provided  herein are
cumulative and not exclusive of any remedies provided by law.

                  (m)  SEVERABILITY.   If  any  term,  provision,   covenant  or
restriction  of  this  Agreement  is  held  to  be  invalid,  illegal,  void  or
unenforceable in any respect, the remainder of the terms, provisions,  covenants
and  restrictions  set forth  herein  shall  remain in full force and effect and
shall in no way be affected,  impaired or  invalidated,  and the parties  hereto
shall use their  reasonable  efforts to find and employ an alternative  means to
achieve the same or substantially  the same result as that  contemplated by such
term, provision,  covenant or restriction.  It is hereby stipulated and declared
to be the  intention of the parties that they would have  executed the remaining
terms, provisions, covenants and restrictions without including any of such that
may be hereafter declared invalid, illegal, void or unenforceable.

                  (n) HEADINGS. The headings herein are for convenience only, do
not  constitute  a part of this  Agreement  and  shall not be deemed to limit or
affect any of the provisions hereof.

                  (o) SHARES HELD BY THE COMPANY  AND ITS  AFFILIATES.  Whenever
the  consent or approval of Holders of a  specified  percentage  of  Registrable
Securities is required hereunder,  Registrable Securities held by the Company or
its  Affiliates  (other than any Holder or  transferees or successors or assigns
thereof  if such  Holder is deemed  to be an  Affiliate  solely by reason of its


                                      -15-
<PAGE>

holdings of such  Registrable  Securities)  shall not be counted in  determining
whether  such  consent or  approval  was given by the  Holders of such  required
percentage and shall not be counted as outstanding.

                  (p)  FORCE   MAJEURE.   If  either  party  is  prevented  from
performing any of its  obligations  under this Agreement due to any cause beyond
the party's reasonable control, including, without limitation, an act of God, an
act of terrorism,  fire,  flood,  explosion,  war, strike,  embargo,  government
regulation,  civil or military authority,  the time for that party's performance
will be extended for the period of the delay or inability to perform due to such
occurrence.



                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]



















                                      -16-
<PAGE>

                  IN WITNESS  WHEREOF,  the  parties  hereto  have  caused  this
Registration Rights Agreement to be duly executed by their respective authorized
persons as of the date first indicated above.


                                       IGEN INTERNATIONAL, INC.




                                       By:  /s/ Samuel J. Wohlstadter
                                            -------------------------
                                            Name:   Samuel J. Wohlstadter
                                            Title:  Chairman and Chief Executive
                                                    Officer


                                       ACQUA WELLINGTON PRIVATE
                                       PLACEMENT FUND, LTD.



                                       By:  /s/ Michael W. Taylor
                                            ----------------------
                                            Name:  Michael W. Taylor
                                            Title: Director


</TEXT>
</DOCUMENT>
