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                                                                   EXHIBIT 10.25



           FIRST AMENDMENT TO THE LICENSE AND SUPPLY AGREEMENT BETWEEN

                           COR THERAPEUTICS AND SOLVAY



           This Amendment is entered into effective as of 13 March 1995 between
COR THERAPEUTICS, INC. ("COR"), a Delaware Corporation, with its principal
offices at 256 East Grand Avenue, South San Francisco, California 94080, U.S.A.
and SOLVAY, SOCIETE ANONYME ("SOLVAY"), a Belgian corporation, with its
principal offices at 33, rue du Prince Albert, 1050 Bruxelles, Belgium.

                                   WITNESSETH

           WHEREAS, COR and Solvay have entered into a License and Supply
Agreement effective as of 27 July 1994 (the "Agreement") on their behalf and on
behalf of their Affiliates (as defined in the Agreement);

           WHEREAS, COR and Solvay are willing to modify a provision of the
Agreement;

           NOW, THEREFORE, in consideration of the foregoing, the parties agree
to amend the Agreement as follows:

           In Section 2.2, on page 5, replace line 13 by "(...) as the breach or
default remains uncured. If by 15 June 1995, SOLVAY and COR have not (...)".

           All the other provisions of the Agreement shall remain unchanged and
in full force and effect.

           IN WITNESS WHEREOF, COR and Solvay have executed this Amendment to be
effective on the date first set forth hereabove.

COR THERAPEUTICS, Inc.                     SOLVAY S.A.



By:                                        By:
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Title:                                     Title:
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