FILED BY COR THERAPEUTICS, INC.
                                                      PURSUANT TO RULE 425 UNDER
                                           THE SECURITIES ACT OF 1933 AND DEEMED

                                                   FILED PURSUANT TO RULE 14a-12
                                         OF THE SECURITIES EXCHANGE ACT OF 1934.

                                        SUBJECT COMPANY:  COR Therapeutics, Inc.

                                                  COMMISSION FILE NO.  000-19290

The merger agreement for Millennium Pharmaceuticals, Inc.'s acquisition of COR
Therapeutics, Inc. was filed by COR Therapeutics, Inc. under cover of Form 8-K
today and is incorporated by reference into this filing.

IMPORTANT ADDITIONAL INFORMATION WILL BE FILED WITH THE SEC

Millennium plans to file with the SEC a Registration Statement on Form S-4 in
connection with the transaction and Millennium and COR plan to file with the SEC
and mail to their respective stockholders a Joint Proxy Statement/Prospectus in
connection with the transaction. The Registration Statement and the Joint Proxy
Statement/Prospectus will contain important information about Millennium, COR,
the transaction and related matters. Investors and security holders are urged to
read the Registration Statement and the Joint Proxy Statement/Prospectus
carefully when they are available.

Investors and security holders will be able to obtain free copies of the
Registration Statement and the Joint Proxy Statement/Prospectus and other
documents filed with the SEC by Millennium and COR through the web site
maintained by SEC at www.sec.gov.
                     -----------

In addition, investors and security holders will be able to obtain free copies
of the Registration Statement and the Joint Proxy Statement/Prospectus from
Millennium by contacting Gina Brazier or from COR by contracting Shari Annes.

Millennium and COR, and their respective directors and executive officers, may
be soliciting proxies from Millennium's or COR's stockholders in connection with
the transaction. A list of the names of Millennium's directors and executive
officers and description of their interests in Millennium is contained in
Millennium's proxy statement dated March 26, 2001, its Annual Report on Form
10-K for the year ended December 31, 2000, and its Current Report on Form 8-K
dated December 6, 2001, which documents are filed with the SEC. A list of the
names of COR's directors and executive officers and descriptions of their
interests in COR is contained in COR's proxy statement dated April 26, 2001, its
Annual Report on Form 10-K for the year ended December 31, 2000, and its Current
Report on Form 8-K dated December 6, 2001, which documents are filed with the
SEC. A more complete description will be available in the Registration Statement
and the Joint Statement/Prospectus.

                                       1.