EXHIBIT 10.1

                                AMENDMENT TO THE
                                BIOGEN IDEC INC.
                            2003 OMNIBUS EQUITY PLAN

            The Biogen Idec Inc. 2003 Omnibus Equity Plan (the "Plan") is hereby
            amended in accordance with its terms as follows:

1.    The first paragraph of Section 4 of the Plan is hereby amended by adding
      the following sentence to the end of such paragraph:

      "The Committee may, in its discretion and to the extent permitted under
      applicable law and the requirements of any securities exchange upon which
      the securities of the Company trade, delegate to an officer or officers of
      the Company the ability to make Awards under the Plan, subject to such
      restrictions and limitations as the Committee may specify in the
      resolution authorizing such delegation."

2.    Except as set forth in this Amendment, the Plan shall remain in full force
      and effect.