EXHIBIT 5

                               PALMER & DODGE LLP
                    One Beacon Street, Boston, MA 02108-3190


TELEPHONE: (617) 573-0100                             FACSIMILE: (617) 227-4420

                                August 28, 2001

Genzyme Corporation
One Kendall Square
Cambridge, Massachusetts 02139

     We are rendering this opinion in connection with the Registration
Statement on Form S-3 (the "Registration Statement") filed by Genzyme
Corporation (the "Company"), a Massachusetts corporation, with the Securities
and Exchange Commission under the Securities Act of 1933, as amended (the
"Securities Act"), on or about the date hereof. The Registration Statement
relates to the resale of up to 2,064,438 shares (the "Shares") of Genzyme
General Division common stock, $0.01 par value per share, that will be issued
to stockholders of Novazyme Pharmaceuticals, Inc. ("Novazyme") in connection
with the Company's acquisition of Novazyme pursuant to an Agreement and Plan
of Merger, dated as of August 6, 2001, among the Company, Rodeo Merger Corp.
and Novazyme (the "Merger Agreement"). We understand that the Shares are to
be offered and sold in the manner described in the Registration Statement.

     We have acted as your counsel in connection with the preparation of the
Registration Statement and are familiar with the proceedings taken by the
Company in connection with the authorization and issuance of the Shares. We have
examined such documents as we consider necessary to enable us to render this
opinion.

     Based upon the foregoing, we are of the opinion that upon issuance in
accordance with the terms of the Merger Agreement, the Shares will be duly
authorized, validly issued, fully paid and nonassessable.

     The foregoing opinion is limited to the Massachusetts Business Corporation
Law and the federal laws of the United States.

     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to our firm under the caption "Legal
Matters" in the prospectus filed as part thereof.

                                       Very truly yours,

                                       /s/ PALMER & DODGE LLP

                                       PALMER & DODGE LLP