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


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

                                October 27, 2000

Genzyme Corporation
One Kendall Square
Cambridge, Massachusetts 02139

Ladies and Gentlemen:

     We have acted as counsel to Genzyme Corporation ("Genzyme"), a
Massachusetts corporation, in connection with (1) the proposed amendment and
restatement of the Genzyme charter to create the GBS Division Common Stock
and cancel the GSP Division Common Stock and the GTR Division Common Stock,
and the proposed exchange of the outstanding shares of GSP Division Common
Stock and GTR Division Common Stock for shares of GBS Division Common Stock
(collectively, the "Tracking Stock Exchanges") and (2) the proposed merger
(the "Merger") of Biomatrix, Inc. ("Biomatrix"), a Delaware corporation, with
and into Seagull Merger Corporation ("Merger Sub"), a Massachusetts
corporation and a wholly-owned subsidiary of Genzyme. The Tracking Stock
Exchanges and the Merger will be consummated pursuant to an Agreement and
Plan of Merger dated as of March 6, 2000, as amended by Amendment No. 1 dated
as of April 17, 2000, Amendment No. 2 dated as of August 25, 2000, and
Amendment No. 3 dated as of October 25, 2000 (the "Merger Agreement"), by and
among Genzyme, Merger Sub and Biomatrix. The Tracking Stock Exchanges and the
Merger are described in the Registration Statement on Form S-4 (the
"Registration Statement") of which this exhibit is a part. This opinion is
being rendered pursuant to the requirements of Item 21(a) of Form S-4 under
the Securities Act of 1933, as amended. Capitalized terms not defined herein
have the meanings set forth in the Merger Agreement and the documents related
thereto.

     In preparing this opinion, we have examined and relied upon (i) the
Restated Articles of Organization of Genzyme, as amended to date (the "Restated
Articles"), (ii) the Merger Agreement, (iii) the Joint Proxy
Statement/Prospectus included in the Registration Statement (the "Joint Proxy
Statement"), (iv) the tax representation letters delivered to us by Genzyme,
Merger Sub and Biomatrix in connection with this opinion (the "Representation
Letters"), and (v) such other documents as we have deemed necessary or
appropriate in order to enable us to render this opinion. In our examination of
documents, we have assumed the authenticity of original documents, the accuracy
of copies, the genuineness of signatures, and the legal capacity of signatories.

     In rendering this opinion, we have assumed without investigation or
verification that the facts relating to the Tracking Stock Exchanges and the
Merger as described in the Joint Proxy Statement are true, correct and complete
in all material respects; that all representations and warranties contained in
the Joint Proxy Statement, the Merger Agreement and the Representation Letters
are, at the time they are made, and will remain at all times through the
Effective Time, true, correct and complete and may be relied upon by us at the
time they are made and at all



Genzyme Corporation
October 27, 2000
Page 2


times through the Effective Time; and that, as to all matters for which a person
or entity has represented that such person or entity is not a party to, does not
have, or is not aware of, any plan, intention, understanding or agreement, there
is no such plan, intention, understanding or agreement. We have further assumed
that all parties to the Merger Agreement and to any other documents examined by
us have acted, and will act, in accordance with the terms of such Merger
Agreement and documents; that the terms of the GSP Division Common Stock and GTR
Division Common Stock exchanged for GBS Division Common Stock in the Tracking
Stock Exchanges will be substantially in the form set forth in the Restated
Articles; that the terms of the GBS Division Common Stock issued in the Tracking
Stock Exchanges and the Merger will be substantially in the form set forth in
Annex F of the Joint Proxy Statement, that the Tracking Stock Exchanges will be
consummated prior to or at the Effective Time and the Merger will be consummated
at the Effective Time pursuant to the terms, conditions and covenants set forth
in the Merger Agreement (including, without limitation, the effecting of the
Merger in accordance with the General Corporation Law of the State of Delaware
and the Massachusetts Business Corporation Law) without the waiver or
modification of any such terms, conditions and covenants; and that Genzyme,
Merger Sub and Biomatrix each will comply with all reporting obligations
required under the Internal Revenue Code of 1986, as amended (the "Code"), and
Treasury Regulations with respect to the Merger. Any inaccuracy in, or breach
of, any of the aforementioned statements, representations or assumptions could
adversely affect our opinion.

     Our opinion is based on existing provisions of the Code, Treasury
Regulations, judicial decisions and rulings and other pronouncements of the
Internal Revenue Service (the "IRS") as in effect on the date of this opinion,
all of which are subject to change (possibly with retroactive effect) or
reinterpretation. No assurances can be given that a change in the law on which
our opinion is based or the interpretation thereof will not occur or that such
change will not affect the opinion expressed herein. We undertake no
responsibility to advise you of any such developments in the law after the
Effective Time.

     No ruling has been or will be sought from the IRS by Genzyme as to the
United States federal income tax consequences of any aspect of the Tracking
Stock Exchanges or by Genzyme, Biomatrix and Merger Sub as to the United States
federal income tax consequences of any aspect of the Merger, and our opinion is
not binding upon either the IRS or any court. Thus, no assurances can be given
that a position taken in reliance on our opinion will not be challenged by the
IRS or rejected by a court.

     Based upon and subject to the foregoing, the discussion in the Joint Proxy
Statement under the heading "Material United States Federal Income Tax
Consequences of the Merger and the Tracking Stock Exchanges," subject to the
limitations and qualifications described therein, fairly and accurately
constitutes our opinion as to the material United States federal income tax
consequences of the Tracking Stock Exchanges and the Merger.

     Our opinion addresses only the specific United States federal income tax
consequences of the Tracking Stock Exchanges and the Merger set forth herein,
and does not address any other federal, state, local, or foreign income, estate,
gift, transfer, sales, use or other tax consequences



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October 27, 2000
Page 3

that may result from the Merger or any other transaction (including any
transaction other than the Tracking Stock Exchanges undertaken in connection
with the Merger).

     This opinion is being provided to you solely for use in connection with the
Registration Statement, and this opinion letter may not be used, circulated,
quoted, or otherwise referred to for any other purpose. We hereby consent to the
use of our name under the caption "Material United States Federal Income Tax
Consequences of the Merger and the Tracking Stock Exchanges" in the Registration
Statement and to the filing of this opinion as an exhibit to the Registration
Statement.

                                                  Very truly yours,

                                                  /s/ Palmer & Dodge LLP