BIOGEN IDEC INC
EX-10.1 AMENDMENT TO 1998 STOCK PLAN
<DOCUMENT>
<TYPE>EX-10.1
<SEQUENCE>2
<FILENAME>b51131biexv10w1.txt
<DESCRIPTION>EX-10.1 AMENDMENT TO 1998 STOCK PLAN
<TEXT>
<PAGE>

                                  EXHIBIT 10.1

             IDEC PHARMACEUTICALS CORPORATION 1988 STOCK OPTION PLAN

                                    AMENDMENT

      The IDEC Pharmaceuticals Corporation 1988 Stock Option Plan, as heretofore
amended and restated effective February 19, 2003, is hereby further amended as
follows:

Section V.3 of the Plan is amended in its entirety to read as follows:

            Limited Transferability of Options. During the lifetime of the
      optionee, Incentive Options shall be exercisable only by the optionee and
      shall not be assignable or transferable other than by will or by the laws
      of descent and distribution following the optionee's death. Non-statutory
      options may be assigned or transferred in whole or in part (i) during the
      optionee's lifetime to one or more members of the optionee's immediate
      family or to a trust established exclusively for one or more such family
      members, (ii) pursuant to a qualified domestic relations order, as defined
      by the Internal Revenue Code or Title 1 of the Employee Retirement Income
      Security Act or the rules thereunder, or (iii) by will or by the laws of
      descent and distribution following the optionee's death. The assigned
      portion may only be exercised by the person or persons who acquire a
      proprietary interest in the option pursuant to the assignment. The terms
      applicable to the assigned portion shall be the same as those in effect
      for the option immediately prior to such assignment and shall be set forth
      in such documents issued to the assignee as the Plan Administrator may
      deem appropriate. The provisions of this Section V.3 shall be retroactive
      and shall apply to all outstanding options granted under the Plan,
      regardless of the date of grant.

                                 BIOGEN IDEC INC.

Date: April 16, 2004             By: /s/ Craig Eric Schneier
                                     ------------------------------------------
                                     Craig Eric Schneier
                                     Executive Vice President - Human Resources


</TEXT>
</DOCUMENT>
