IGEN INTERNATIONAL INC /DE
EXHIBIT 10.2
<DOCUMENT>
<TYPE>EX-10
<SEQUENCE>4
<FILENAME>igen481052.txt
<DESCRIPTION>EXHIBIT 10.2
<TEXT>
                                                                    Exhibit 10.2


                               PURCHASE AGREEMENT
                               ------------------

      This PURCHASE AGREEMENT (this "AGREEMENT"),  dated as of December 7, 2001,
is entered into 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"),  for the
purchase and sale of shares of the common stock,  par value $.001 per share (the
"COMMON STOCK"),  of the Company by the Purchaser,  in the manner,  and upon the
terms, provisions and conditions set forth in this Agreement.

      WHEREAS,  the  parties  desire  that,  upon the terms and  subject  to the
conditions  contained herein,  the Company shall issue and sell to the Purchaser
and Purchaser shall purchase shares of Common Stock; and

      WHEREAS,  such  purchase  and  sale  will  be made in  reliance  upon  the
provisions of Section 4(2) and Rule 506 of Regulation D ("Regulation  D") of the
United States  Securities Act of 1933, as amended,  and regulations  promulgated
thereunder  (the  "Securities  Act"),  or upon  such  other  exemption  from the
registration requirements of the Securities Act as may be available with respect
to any or all of the purchases of Common Stock to be made hereunder.

      NOW, THEREFORE,  in consideration of the  representations,  warranties and
agreements  contained  herein and other  good and  valuable  consideration,  the
receipt and legal adequacy of which is hereby  acknowledged by the parties,  the
Company and the Purchaser hereby agree as follows:

      1. PURCHASE PRICE.

           (a) Upon the following terms and subject to the conditions  contained
herein,  the Purchaser hereby agrees to purchase 397,882 shares of the Company's
Common  Stock  (the  "Shares")  at a per share  price of  $29.4462  ("Per  Share
Purchase  Price")  and for an  aggregate  purchase  price  of  $11,716,104  (the
"Purchase Price").

           (b) The Company has  authorized  and has  reserved  and  covenants to
continue to reserve,  free of preemptive  rights and other  similar  contractual
rights of  stockholders,  a  sufficient  number of its  authorized  but unissued
shares of Common Stock, to effect the issuance of the Shares.

           (c) In   consideration   of  and  in  express   reliance   upon  the
representations,  warranties, covenants, terms and conditions of this Agreement,
the Company  agrees to issue and sell to the Purchaser and the Purchaser  agrees
to purchase the Shares.  The closing under this Agreement (the "Closing")  shall
take place at the offices of Jenkens & Gilchrist Parker Chapin LLP, The Chrysler
Building,  405 Lexington  Avenue,  New York,  New York 10174 at 1:00 p.m. on the
date hereof  (eastern time) upon the  satisfaction of each of the conditions set
forth in Sections 4 and 5 hereof (the "Closing Date").

<PAGE>

      2.  REPRESENTATIONS,  WARRANTIES  AND  COVENANTS  OF  THE  PURCHASER.  The
Purchaser  represents and warrants to the Company, and covenants for the benefit
of the Company, as follows:

           (a) The  Purchaser is a limited  liability  company  duly  organized,
validly  existing and in good standing under the laws of the Commonwealth of The
Bahamas.

           (b) This  Agreement has been duly  authorized,  validly  executed and
delivered by the Purchaser and is a valid and binding  agreement and  obligation
of the Purchaser enforceable against the Purchaser in accordance with its terms,
subject to limitations  on  enforcement  by general  principles of equity and by
bankruptcy  or  other  laws  affecting  the  enforcement  of  creditors'  rights
generally, and the Purchaser has full power and authority to execute and deliver
this Agreement and the other agreements and documents contemplated hereby and to
perform its obligations hereunder and thereunder.

           (c) The Purchaser has received and carefully  reviewed  copies of the
Public  Documents (as hereinafter  defined).  The Purchaser  understands that no
Federal,  state, local or foreign  governmental body or regulatory authority has
made any finding or  determination  relating to the fairness of an investment in
any of the Shares and that no Federal, state, local or foreign governmental body
or  regulatory  authority  has  recommended  or endorsed,  or will  recommend or
endorse,  any  investment  in any of the Shares.  The  Purchaser,  in making the
decision to purchase the Shares, has relied upon independent  investigation made
by it and has not relied on any  information  or  representations  made by third
parties.

           (d) The Purchaser  understands  that the Shares are being offered and
sold to it in reliance on specific  provisions  of Federal and state  securities
laws and  that the  Company  is  relying  upon the  truth  and  accuracy  of the
representations,  warranties, agreements,  acknowledgments and understandings of
the Purchaser set forth herein for purposes of qualifying  for  exemptions  from
registration under the Securities Act, and applicable state securities laws.

           (e) The Purchaser is an  "accredited  investor" as defined under Rule
501 of Regulation D promulgated under the Securities Act.

           (f) The  Purchaser  is and  will be  acquiring  the  Shares  for such
Purchaser's  own account,  and not with a view to any resale or  distribution of
the  Shares  in whole or in part,  in  violation  of the  Securities  Act or any
applicable securities laws.

           (g) The offer and sale of the Shares is  intended  to be exempt  from
registration under the Securities Act, by virtue of Section 4(2) and Rule 506 of
Regulation D promulgated  under the  Securities  Act. The Purchaser  understands
that the Shares purchased  hereunder have not been, and may never be, registered
under the  Securities Act and that none of the Shares can be sold or transferred
unless they are first  registered  under the  Securities  Act and such state and
other  securities laws as may be applicable or in the opinion of counsel for the
Company an exemption  from  registration  under the  Securities Act is available
(and then the Shares may be sold or  transferred  only in  compliance  with such
exemption and all applicable state and other securities laws).


                                      -2-
<PAGE>

           (h) The Purchaser (i) has such  knowledge and experience in financial
and business  matters as to be capable of evaluating  the merits and risks of an
investment in the Company; and (ii) recognizes that such Purchaser's  investment
in the Company involves a high degree of risk.

           (i) The Purchaser is capable of evaluating the risks and merits of an
investment  in the Shares by virtue of its  experience  as an  investor  and its
knowledge,  experience, and sophistication in financial and business matters and
such  Purchaser is capable of bearing the entire loss of its  investment  in the
Shares.

           (j) The  Purchaser  is  neither  a  registered  broker-dealer  nor an
affiliate of a registered broker-dealer.

           (k) The Purchaser and its advisors,  if any, have been furnished with
all materials  relating to the business,  finances and operations of the Company
and  materials  relating  to the offer and sale of the  Shares  which  have been
requested by the  Purchaser.  The Purchaser and its advisors,  if any, have been
afforded the  opportunity  to ask  questions of the Company.  The  Purchaser has
sought such accounting,  legal and tax advice as it has considered  necessary to
make an informed  investment  decision  with respect to its  acquisition  of the
Shares. Purchaser understands that it (and not the Company) shall be responsible
for its own tax liabilities that may arise as a result of this investment or the
transactions  contemplated by this Agreement. The Purchaser has not obtained any
material non-public information from the Company.

           (l) The Purchaser shall comply with all applicable federal securities
laws,  rules and regulations in connection with the sale of the Shares purchased
by the Purchase hereunder.

      3.  REPRESENTATIONS,  WARRANTIES AND COVENANTS OF THE COMPANY. The company
represents and warrants to the  Purchaser,  and covenants for the benefit of the
Purchaser, as follows:

           (a) The Company has been duly  incorporated  and is validly  existing
and in good  standing  under  the  laws of the  state  of  Delaware,  with  full
corporate  power and authority to own,  lease and operate its  properties and to
conduct  its  business  as  currently  conducted,  and is  duly  registered  and
qualified to conduct its business and is in good  standing in each  jurisdiction
or place  where the nature of its  properties  or the  conduct  of its  business
requires  such  registration  or  qualification,  except  where the  failure  to
register or qualify would not have a Material  Adverse  Effect.  For purposes of
this Agreement, "Material Adverse Effect" shall mean any effect on the business,
results of operations,  prospects,  assets or financial condition of the Company
that is material and adverse to the Company and its subsidiaries and affiliates,
taken as a whole and/or any  condition,  circumstance,  or situation  that would
prohibit or otherwise  materially interfere with the ability of the Company from
entering into and performing any of its obligations  under this Agreement in any
material  respect;  provided,  however,  that the  foregoing  shall not  include
operating  losses of the Company in the amounts  contemplated  by the Commission
Documents.

                                      -3-
<PAGE>

      (b) The Company has furnished  the Purchaser  with copies of the Company's
Annual  Report on Form 10-K for  fiscal  year  ended  March 31,  2001 (the "FORM
10-K") filed with the Securities and Exchange  Commission (the "COMMISSION") and
its Form 10-Q for the  quarterly  period  ended  September  30,  2001 (the "FORM
10-Q";  collectively  with the Form 10-K,  the "PUBLIC  DOCUMENTS").  The Public
Documents at the time of their filing did not include any untrue  statement of a
material fact or omit to state any material fact  necessary in order to make the
statements  contained  therein,  in light of the circumstances  under which they
were made, not  misleading.  As used herein,  "COMMISSION  DOCUMENTS"  means all
reports,  schedules,  forms, statements and other documents filed by the Company
with the Commission after March 31, 2001 pursuant to the reporting  requirements
of the Exchange Act, including material filed pursuant to Section 13(a) or 15(d)
of the Exchange Act.

           (c) The Shares have been duly  authorized by all necessary  corporate
action and, when paid for by the  Purchaser  and issued in  accordance  with the
terms hereof, the Shares shall be validly issued, fully paid and non-assessable.

           (d) Each of this  Agreement  and the  Registration  Rights  Agreement
attached hereto as EXHIBIT A (the "REGISTRATION RIGHTS AGREEMENT") has been duly
authorized,  validly  executed  and  delivered on behalf of the Company and is a
valid and binding  agreement and obligation of the Company  enforceable  against
the Company in accordance with its terms,  subject to limitations on enforcement
by general  principles of equity and by  bankruptcy or other laws  affecting the
enforcement of creditors' rights  generally,  and the Company has full power and
authority to execute and deliver this  Agreement  and the other  agreements  and
documents  contemplated  hereby and to perform  its  obligations  hereunder  and
thereunder.

           (e)  Except as  disclosed  in  SCHEDULE  3(e)  attached  hereto,  the
execution and delivery of this Agreement and the Registration  Rights Agreement,
the  issuance  of any of the Shares  and the  consummation  of the  transactions
contemplated  by this  Agreement and the  Registration  Rights  Agreement by the
Company,  will not (i) conflict with or result in a breach of or a default under
any  of  the  terms  or  provisions   of,  (A)  the  Company's   certificate  of
incorporation  or by-laws,  or (B) of any material  provision of any  indenture,
mortgage,  deed of trust or other material  agreement or instrument to which the
Company is a party or by which it or any of its material properties or assets is
bound, (ii) result in a violation of any material provision of any law, statute,
rule,  regulation,  or any existing applicable decree,  judgment or order by any
court,  Federal  or  state  regulatory  body,  administrative  agency,  or other
governmental body having  jurisdiction over the Company,  or any of its material
properties  or  assets or (iii)  result in the  creation  or  imposition  of any
material lien, charge or encumbrance upon any material property or assets of the
Company or any of its  subsidiaries  pursuant to the terms of any  agreement  or
instrument  to which any of them is a party or by which any of them may be bound
or to which any of their  property or any of them is subject  except in the case
of clauses (i)(B) or (iii) for any such conflicts,  breaches, or defaults or any
liens, charges, or encumbrances which would not have a Material Adverse Effect.

           (f) The sale and issuance of the Shares in accordance  with the terms
of and in  reliance  on the  accuracy  of the  Purchaser's  representations  and
warranties  set forth in this  Agreement  will be exempt  from the  registration
requirements of the Securities Act.

                                      -4-
<PAGE>

           (g)  No  consent,   approval  or  authorization  of  or  designation,
declaration or filing with any governmental authority on the part of the Company
is  required  in  connection  with the  valid  execution  and  delivery  of this
Agreement or the offer,  sale or issuance of the Shares or the  consummation  of
any other  transaction  contemplated  by this Agreement  (other than any filings
which may be  required  to be made by the Company  with the  Commission,  or the
Nasdaq  National  Market or pursuant to any state or "blue sky"  securities laws
subsequent to the Closing,  and, any  registration  statement which may be filed
pursuant to this Agreement).

           (h) There is no action,  suit,  claim,  investigation  or  proceeding
pending or, to the  knowledge  of the  Company,  threatened  against the Company
which  questions  the  validity of this  Agreement  or the  Registration  Rights
Agreement or the transactions  contemplated thereby or any action taken or to be
taken pursuant thereto.  Except as disclosed in the Commission Documents,  there
is no action,  suit,  claim,  investigation  or  proceeding  pending  or, to the
knowledge of the Company,  threatened,  against or involving  the Company or any
subsidiary,  or any of their respective properties or assets which, if adversely
determined, is reasonably likely to result in a Material Adverse Effect.

           (i)  Subsequent to the dates as of which  information is given in the
Public  Documents,  Commission  Documents,  this  Agreement or the  Registration
Rights Agreement and except as contemplated herein, the Company has not incurred
any material  liabilities  or material  obligations,  direct or  contingent,  or
entered into any material transactions not in the ordinary course of business.

           (j) The Company has sufficient title and ownership of all trademarks,
service  marks,  trade  names,  copyrights,  patents,  trade  secrets  and other
proprietary rights  ("INTELLECTUAL  PROPERTY") necessary for its business as now
conducted  and as proposed to be conducted as described in the Public  Documents
or the  Commission  Documents  except for any of the  foregoing,  the absence of
which would not reasonably be likely to result in a Material Adverse Effect and,
to its  knowledge  without any conflict  with or  infringement  of the rights of
others. Except as set forth in the Public Documents or the Commission Documents,
there are no material  outstanding  options,  licenses or agreements of any kind
relating to the Intellectual  Property,  nor is the Company bound by or party to
any material  options,  licenses or  agreements  of any kind with respect to the
Intellectual Property of any other person or entity.

           (k) The Company  has  complied  and will  comply with all  applicable
federal and state  securities  laws in connection  with the offer,  issuance and
sale of the Shares  hereunder.  Neither  the  Company  nor anyone  acting on its
behalf,  directly  or  indirectly,  has or will  sell,  offer to sell or solicit
offers to buy any of the Shares,  or similar  securities  to, or solicit  offers
with  respect  thereto  from,  or enter into any  preliminary  conversations  or
negotiations  relating  thereto with, any person,  or has taken or will take any
action  so as to bring  the  issuance  and sale of any of the  Shares  under the
registration  provisions of the Securities Act and any other applicable  federal
and state  securities laws.  Neither the Company nor any of its affiliates,  nor
any person  acting on its or their  behalf,  has  engaged in any form of general
solicitation  or general  advertising  (within the meaning of Regulation D under
the Securities Act) in connection with any of the Shares.

                                      -5-
<PAGE>

           (l) To the  Company's  knowledge,  neither  this  Agreement  nor  the
Schedules  hereto  nor the  Registration  Rights  Agreement  contain  any untrue
statement of a material fact or omit to state a material fact necessary in order
to make the statements made herein or therein, in the light of the circumstances
under which they were made herein or therein, not misleading.

           (m) The  authorized  capital  stock  of the  Company  and the  shares
thereof  issued  and  outstanding  as of  September  30,  2001 are set  forth on
SCHEDULE 3(m) attached  hereto.  All of the outstanding  shares of the Company's
Common  Stock  have been duly and  validly  authorized,  and are fully  paid and
non-assessable. Except as set forth in this Agreement, the Public Documents, the
Commission  Documents or on SCHEDULE 3(m) attached  hereto,  as of September 30,
2001,  no  shares  of  Common  Stock  are  entitled  to  preemptive   rights  or
registration  rights  and there are no  outstanding  options,  warrants,  scrip,
rights to subscribe to, call or commitments of any character whatsoever relating
to, or securities or rights convertible into, any shares of capital stock of the
Company.  Furthermore,  except as set  forth in this  Agreement,  in the  Public
Documents,  the Commission  Documents or on SCHEDULE 3(m) as of the date hereof,
there are no contracts,  commitments,  understandings,  or arrangements by which
the  Company is or may become  bound to issue  additional  shares of the capital
stock of the Company or options, securities or rights convertible into shares of
capital stock of the Company. Except as disclosed in the Commission Documents or
the Public Documents and except for customary transfer restrictions contained in
agreements  entered into by the Company in order to sell restricted  securities,
as of the date  hereof,  the  Company is not a party to any  agreement  granting
registration  rights to any  person  with  respect  to any of its equity or debt
securities.  The Company is not a party to, and its  executive  officers have no
knowledge of, any agreement  restricting the voting or transfer of any shares of
the  capital  stock of the  Company.  The offer and sale of all  capital  stock,
convertible securities, rights, warrants, or options of the Company issued prior
to the Closing  complied with all applicable  federal and state securities laws,
or no  stockholder  has a right of  rescission  or damages with respect  thereto
which is reasonably  likely to have a Material  Adverse Effect.  The Company has
furnished or made  available  to the  Purchaser  true and correct  copies of the
Company's  Certificate  of  Incorporation  as in effect on the date  hereof (the
"CERTIFICATE"),  and the  Company's  Bylaws as in effect on the date hereof (the
"BYLAWS").

           (n) Prior to the  effectiveness  of the  Registration  Statement  (as
defined  in the  Registration  Rights  Agreement),  the  Company  will  use  its
commercially  reasonable  efforts to list the  Shares for  trading on the Nasdaq
National Market or any relevant market or system, if applicable, and will comply
in all  material  respects  with  the  Company's  reporting,  filing  and  other
obligations  under the  bylaws  or rules of the  Nasdaq  National  Market or any
relevant market or system.

           (o) Except for the disclosure of this Agreement and the  Registration
Rights  Agreement  and  information  contained  therein  to the  holders  of the
Company's  5%   subordinated   convertible   debentures,   consistent  with  the
requirements  of the  related  purchase  agreement,  the Company may not issue a
press release or otherwise make a public statement or announcement  with respect
to the transaction  contemplated  hereby prior to the Closing Date. In the event
that the Company is required by law or  regulations  to issue a press release or
otherwise make a public statement or announcement with respect to this Agreement
after the Closing Date, the Company shall consult with the Purchaser on the form


                                      -6-
<PAGE>

and substance of such press release or other disclosure.

           (p) Prior to the  effectiveness  of the Registration  Statement,  the
Company may enter into an agreement with a third party, the principal purpose of
which is to secure  equity  financing  (an "Other  Financing").  If prior to the
effectiveness  of the  Registration  Statement the Company  enters into an Other
Financing  at a price per share  less than the  Purchaser's  Per Share  Purchase
Price,  the  Company  will issue  additional  shares to the  Purchaser  based on
standard "weighted average"  anti-dilution formula (the "ANTI-DILUTION  SHARES")
as set forth on SCHEDULE 3(p) hereof. If issued, the Anti-Dilution Shares shall,
at  the  Purchaser's  option,  if  appropriate,  be  registered  in  a  separate
registration  statement. As used herein, "OTHER FINANCING" shall not include the
Company  (i)  entering  into a loan,  credit  or lease  facility  with a bank or
financing   institution   (including  any  equity   component   thereof),   (ii)
establishing an employee stock option plan or agreement, (iii) issuing shares of
Common Stock in connection  with the Company's  option plans (as the same may be
amended  from time to time),  stock  purchase  plans,  rights  plans,  currently
outstanding  warrants or options  (unless the exercise price of such warrants or
options are reset to a price below the current exercise price),  or increase the
number of shares available under any such plans (the primary purpose of which is
not to raise equity), (iv) issuing shares of Common Stock upon conversion of the
Company's existing subordinated  convertible debentures and series B convertible
preferred  stock  (unless the  conversion  price of such  debentures or series B
convertible  preferred  stock are reset  (other  than by its stated  terms) to a
price below the current conversion price) and (v) issuing shares of Common Stock
and/or  preferred  stock in  connection  with the  formation or  maintenance  of
strategic   partnerships,   alliances,   licenses  or  joint  ventures  and  the
acquisition   of   products,   licenses  or  other  assets  (each  a  "Permitted
Transaction").

      4.  CONDITIONS  PRECEDENT  TO THE  OBLIGATION  OF THE  COMPANY TO SELL THE
SHARES: The obligation  hereunder of the Company to issue and sell the Shares to
the Purchaser is subject to the satisfaction or waiver, at or before the Closing
Date, of each of the  conditions set forth below.  These  conditions are for the
Company's  sole benefit and may be waived by the Company at any time in its sole
discretion.

           (a) The Purchaser  shall have executed and delivered  this  Agreement
and the Registration Rights Agreement.

           (b) The Purchaser shall have performed, satisfied and complied in all
material respects with all covenants, agreements and conditions required by this
Agreement and the Registration  Rights  Agreement to be performed,  satisfied or
complied with by such Purchaser at or prior to the Closing Date.

           (c) The representations and warranties of the Purchaser shall be true
and  correct  in all  material  respects  as of the date when made and as of the
Closing  Date as  though  made at that  time,  except  for  representations  and
warranties that are expressly made as of a particular  date, which shall be true
and correct in all material respects as of such date.

           (d) At the Closing Date, upon receipt of the certificates  evidencing
the Shares,  the  Purchaser  shall have  delivered  to the  Company  immediately
available funds as payment in full of the Purchase Price for the Shares.


                                      -7-
<PAGE>
           (e) No  statute,  regulation,  executive  order,  decree,  ruling  or
injunction  shall have been  enacted,  entered,  promulgated  or endorsed by any
court or governmental  authority of competent  jurisdiction  which prohibits the
consummation  of any of the  transactions  contemplated  by this Agreement at or
prior to the Closing Date.

           (f) As of the Closing Date, no action,  suit or proceeding  before or
by any court or  governmental  agency or body,  domestic  or  foreign,  shall be
pending  against or  affecting  the  Company,  or any of its  properties,  which
questions the validity of the Agreement,  the  Registration  Rights Agreement or
the transactions contemplated thereby or any action taken or to be take pursuant
thereto.

           (g) The Company  will not be  obligated to issue any shares of Common
Stock which  would  result in the  issuance  under this  Agreement  of more than
fourteen and  nine-tenths  percent (14.9%) of the shares of capital stock deemed
issued and  outstanding  under the  Company's  Rights Plan,  unless the Board of
Directors has approved such issuance.

      5. CONDITIONS PRECEDENT TO THE OBLIGATION OF THE PURCHASER TO PURCHASE THE
SHARES:  The  obligation  hereunder of the  Purchaser to acquire and pay for the
Shares is subject to the satisfaction or waiver,  at or before the Closing Date,
of  each  of the  conditions  set  forth  below.  These  conditions  are for the
Purchaser's  sole benefit and may be waived by the  Purchaser at any time in its
sole discretion.

           (a) The Company shall have executed and delivered  this Agreement and
the Registration Rights Agreement.

           (b) The Company shall have  performed,  satisfied and complied in all
material respects with all covenants, agreements and conditions required by this
Agreement and the Registration  Rights  Agreement to be performed,  satisfied or
complied with by the Company at or prior to the Closing Date.

           (c) Each of the  representations  and warranties of the Company shall
be true and correct in all material  respects as of the date when made and as of
the Closing  Date as though made at that time  (except for  representations  and
warranties that speak as of a particular date),  which shall be true and correct
in all material respects as of such date.

           (d) No  statute,  regulation,  executive  order,  decree,  ruling  or
injunction  shall have been  enacted,  entered,  promulgated  or endorsed by any
court or governmental  authority of competent  jurisdiction  which prohibits the
consummation  of any of the  transactions  contemplated  by this Agreement at or
prior to the Closing Date.

           (e) As of the Closing Date, no action,  suit or proceeding  before or
by any court or  governmental  agency or body,  domestic  or  foreign,  shall be
pending  against or  affecting  the  Company,  or any of its  properties,  which
questions the validity of the Agreement,  the  Registration  Rights Agreement or
the transactions contemplated thereby or any action taken or to be take pursuant
thereto. As of the Closing Date, no action,  suit, claim or proceeding before or
by any court or  governmental  agency or body,  domestic  or  foreign,  shall be
pending against or affecting the Company,  or any of its  properties,  which, if


                                      -8-
<PAGE>

adversely  determined,  is  reasonably  likely to result in a  Material  Adverse
Effect.

           (f) No Material  Adverse  Effect shall have occurred at or before the
Closing Date.

           (g) As of the  Closing  Date,  trading in the Common  Stock shall not
have been  suspended  by the  Commission  or the Nasdaq  National  Market or any
alternate  market  (except  for any  suspension  of trading of limited  duration
agreed to by the Company,  which  suspension  shall be  terminated  prior to the
Closing Date).

           (h) The Company  shall have  delivered  certificates  evidencing  the
Shares to the Purchaser at or before the Closing Date.

           (i) The  Company  shall have  delivered  on the  Closing  Date to the
Purchaser a secretary's certificate, dated as of the Closing Date, as to (i) the
resolutions  of  the  board  of  directors  of  the  Company   authorizing   the
transactions  contemplated by this Agreement,  (ii) the  Certificate,  (iii) the
Bylaws, each as in effect at the Closing,  and (iv) the authority and incumbency
of the officers of the Company  executing  this  Agreement and the  Registration
Rights Agreement.

           (j)  The   Purchaser   shall  have   received  a  legal   opinion  in
substantially the form annexed hereto as Exhibit B as of the Closing Date.

           (k) The  Purchaser  will not be  obligated  to purchase any shares of
Common  Stock which would result in the  issuance  under this  Agreement of more
than  fourteen and  nine-tenths  percent  (14.9%) of the shares of capital stock
deemed issued and outstanding  under the Company's Rights Plan, unless the Board
of Directors has approved such issuance.

      6. LEGENDS. Unless otherwise provided below, each certificate representing
the Shares shall be stamped or otherwise  imprinted with a legend  substantially
in the following form (the "LEGEND"):

           "THE SECURITIES  REPRESENTED BY THIS  CERTIFICATE  HAVE NOT
           BEEN  REGISTERED  UNDER  THE  SECURITIES  ACT OF  1933,  AS
           AMENDED (THE  "SECURITIES  ACT"),  OR ANY STATE  SECURITIES
           LAWS AND MAY NOT BE SOLD, TRANSFERRED OR OTHERWISE DISPOSED
           OF UNLESS  REGISTERED  UNDER THE  SECURITIES  ACT AND UNDER
           APPLICABLE  STATE  SECURITIES  LAWS OR IGEN  INTERNATIONAL,
           INC.  (THE  "COMPANY")  SHALL HAVE RECEIVED AN OPINION FROM
           COUNSEL  TO THE  COMPANY,  IN  FORM,  SCOPE  AND  SUBSTANCE
           REASONABLY  ACCEPTABLE TO THE COMPANY THAT  REGISTRATION OF
           SUCH  SECURITIES  UNDER  THE  SECURITIES  ACT AND UNDER THE
           PROVISIONS OF APPLICABLE  FEDERAL AND STATE SECURITIES LAWS
           IS NOT REQUIRED."

                                      -9-
<PAGE>

      7. FEES AND EXPENSES.  Each of the Company and the Purchaser shall pay its
respective fees and expenses  related to the  transactions  contemplated by this
Agreement and the Registration  Rights Agreement;  except that the Company shall
pay on the  Closing  Date,  all  reasonable  fees  and  expenses,  exclusive  of
disbursements  and  out-of-pocket  expenses,  incurred by the Purchaser of up to
$25,000 in connection with the preparation,  negotiation, execution and delivery
of this Agreement and the Registration Rights Agreement. Neither the Company nor
the  Purchaser  has  employed,  or is subject to the valid claim of, any broker,
finder, investment banker,  consultant,  financial advisor or other intermediary
(collectively "Broker") in connection with the transactions contemplated by this
Agreement who might be entitled to a fee or  commission in connection  with this
Agreement  or the  transactions  contemplated  hereby.  Each party agrees to and
shall  indemnify the other against any claim for a fee or commission made by any
Broker against the other in connection  with this Agreement or the  transactions
contemplated hereby.

8.       INDEMNIFICATION.

           (a) The Company  hereby  agrees to  indemnify  and hold  harmless the
Purchaser  and its  officers,  directors,  shareholders,  employees,  agents and
attorneys  against  any  and  all  losses,  claims,  damages,   liabilities  and
reasonable  expenses  (collectively  "Claims")  incurred  by each such person in
connection  with  defending or  investigating  any such  Claims,  whether or not
resulting in any liability to such person,  to which any such indemnified  party
may become  subject,  insofar as such Claims  arise out of or are based upon any
breach of any  representation  or warranty or  agreement  made by the Company in
this Agreement.

           (b) The  Purchaser  hereby  agrees to indemnify and hold harmless the
Company  and  its  officers,  directors,  shareholders,  employees,  agents  and
attorneys against any and all losses, claims, damages,  liabilities and expenses
incurred by each such person in connection with defending or  investigating  any
such claims or  liabilities,  whether or not  resulting in any liability to such
person,  to which  any such  indemnified  party  may  become  subject  under the
Securities Act, or under any other statute, at common law or otherwise,  insofar
as such  Claims  arise  out of or are based  upon (i) any  untrue  statement  or
alleged  untrue  statement of a material  fact made by the  Purchaser,  (ii) any
omission or alleged omission of a material fact with respect to the Purchaser or
(iii) any  breach  of any  representation,  warranty  or  agreement  made by the
Purchaser in this Agreement.

      9.  GOVERNING  LAW;  CONSENT  TO  JURISDICTION.  This  Agreement  shall be
governed by and interpreted in accordance with the laws of the State of New York
without giving effect to the rules  governing the conflicts of laws. Each of the
parties  consents to the  exclusive  jurisdiction  of the Federal  courts  whose
districts  encompass  any part of the County of New York  located in the City of
New York in connection  with any dispute arising under this Agreement and hereby
waives,  to the maximum extent  permitted by law, any  objection,  including any
objection based on forum non conveniens,  to the bringing of any such proceeding
in such  jurisdictions.  Each party  waives  its right to a trial by jury.  Each
party to this  Agreement  irrevocably  consents to the service of process in any
such  proceeding  by the mailing of copies  thereof by  registered  or certified
mail,  postage prepaid,  to such party at its address set forth herein.  Nothing
herein shall affect the right of any party to serve  process in any other manner
permitted by law.

                                      -10-
<PAGE>

      10.  NOTICES.  All  notices  and  other  communications  provided  for  or
permitted hereunder shall be made in writing by hand delivery, express overnight
courier,  registered  first class mail, or telecopier  (provided that any notice
sent by  telecopier  shall be confirmed by other means  pursuant to this Section
10),  initially to the address set forth  below,  and  thereafter  at such other
address,  notice of which is given in  accordance  with the  provisions  of this
Section.


                           (a)      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

                                    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


                           (b)      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

                                      -11-
<PAGE>

      All such  notices  and  communications  shall be  deemed to have been duly
given:  when  delivered  by hand,  if  personally  delivered;  when  receipt  is
acknowledged,  if  telecopied;  or when actually  received or refused if sent by
other means.

      11. ENTIRE AGREEMENT. This Agreement and the Registration Rights Agreement
constitute the entire understanding and agreement of the parties with respect to
the subject matter hereof and supersedes all prior and/or  contemporaneous  oral
or written  proposals  or  agreements  relating  thereto all of which are merged
herein.  This  Agreement  may not be amended or any  provision  hereof waived in
whole or in part, except by a written amendment signed by both of the parties.

      12.  COUNTERPARTS.  This Agreement may be executed by facsimile  signature
and in counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

                                  [end of page]

                                      -12-
<PAGE>

      IN WITNESS  WHEREOF,  this  Agreement  was duly executed on the date first
written 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>
