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

                                                                    Exhibit 5.1


TELEPHONE: (617) 573-0100                             FACSIMILE: (617) 277-4420


                                    June 30, 2000



Genzyme Corporation
One Kendall Square
Cambridge, Massachusetts 02139


    We are rendering this opinion in connection with the Registration
Statement on Form S-4 (the "Registration Statement") filed by Genzyme
Corporation (the "Company") with the Securities and Exchange Commission under
the Securities Act of 1933, as amended (the "Securities Act"), on April 18,
2000, and amended on or about the date hereof. The Registration Statement
relates to (A) up to 18,743,626 shares (the "Merger Shares") of the Company's
Genzyme Biosurgery Division Common Stock, $0.01 par value per share (the
"GZBX Stock") to be issued in connection with the merger of Biomatrix, Inc.
("Biomatrix") with and into a wholly-owned subsidiary of the Company,
pursuant to the Agreement and Plan of Merger dated as of March 6, 2000, as
amended by Amendment No. 1 to Agreement and Plan of Merger (the "Agreement")
among the Company, Biomatrix and such subsidiary, and (B) up to 24,914,581
shares (the "Exchange Shares")of GZBX Stock to be issued in connection with
the recapitalization (the "Recapitalization") as described in the
Regsitration Statement involving the exchange of the Company's Genzyme
Surgical Products Division Common Stock ("GZSP Stock") and Genzyme Tissue
Repair Division Common Stock ("GZTR Stock") into GZBX Stock. We understand
that the Merger Shares are to be offered and sold and the Exchange Shares are
to be issued, each 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 Merger
Shares and the authorization and issuance of the Exchange 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 approval by the
stockholders of Genzyme of the Recapitalization (A) upon issuance in
accordance with the Agreement, the Merger Shares will be duly authorized,
validly issued, fully paid and nonassessable and (B) upon issuance in
connection with the Recapitalization in the manner described in the
Registration Statement, the Exchange Shares will be duly authorized, validly
issued, fully paid and nonassessable.

    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