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    As filed with the Securities and Exchange Commission on January 8, 1999.

                                                    Registration No. 333-68627
                                                    ==========================


                     U.S. SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                             ----------------------

                   POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-3
             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

                             ----------------------

                               GENZYME CORPORATION
             (Exact name of registrant as specified in its charter)

         MASSACHUSETTS                                       06-1047163
  (State or other jurisdiction                            (I.R.S. Employer
of incorporation or organization)                      Identification Number)

        ONE KENDALL SQUARE, CAMBRIDGE, MASSACHUSETTS 02139 (617) 252-7500
  (Address, including zip code, and telephone number, including area code, of
                   registrant's principal executive offices)

                             ----------------------

                                PETER WIRTH, ESQ.
                Executive Vice President and Chief Legal Officer
                               Genzyme Corporation
                               One Kendall Square
                         Cambridge, Massachusetts 02139
                                 (617) 252-7500
 (Name, address, including zip code, and telephone number, including area code,
                             of agent for service)

                                 with copies to:

                           DAVID R. POKROSS, JR., ESQ.
                               Palmer & Dodge LLP
                                One Beacon Street
                           Boston, Massachusetts 02108
                                 (617) 573-0100

                             ----------------------



     Genzyme Corporation's Registration Statement on Form S-3 (File No.
333-68627) registered 2,018 shares of Genzyme Molecular Oncology Division Common
Stock, $0.01 par value per share, and 1,758 shares of Genzyme Tissue Repair
Division Common Stock, $0.01 par value per share. These shares related to
Genzyme Corporation warrants which expired on December 31, 1998. On or prior to
December 31, 1998, warrants were exercised for 1,379 of the shares of Genzyme
Molecular Oncology Division Common Stock covered by this Registration Statement
and 1,181 of the shares of Genzyme Tissue Repair Division Common Stock covered
by this Registration Statement. Because these warrants have expired, the
offering of the underlying shares has terminated. This Post-Effective Amendment
is filed, consequently, to deregister 639 shares of Genzyme Molecular Oncology
Division Common Stock and 577 shares of Genzyme Tissue Repair Division Common
Stock.


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                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, as amended, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-3 and has duly caused this
Post-Effective Amendment to be signed on its behalf by the undersigned,
thereunto duly authorized, in the City of Cambridge, Commonwealth of
Massachusetts, on January 7, 1999.

                               GENZYME CORPORATION

                        By: /s/ David J. McLachlan                        
                           ---------------------------------------------------
                            David J. McLachlan
                            Executive Vice President and Chief Financial Officer