EXHIBIT 5

                               Palmer & Dodge LLP
                                One Beacon Street
                           Boston, Massachusetts 02108

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


                                 July 27, 2001


Genzyme Corporation
One Kendall Square
Cambridge, Massachusetts 02139

     We are rendering this opinion in connection with the Registration
Statement on Form S-8 (the "Registration Statement") filed by Genzyme
Corporation (the "Company") with the Securities and Exchange Commission (the
"Commission") under the Securities Act of 1933, as amended (the "Act"), on or
about the date hereof. The Registration Statement relates to 235,870 shares
of Genzyme Biosurgery Division common stock, $0.01 par value (the "Shares"),
that are issuable upon the exercise of options assumed by the Company in
connection with the merger of a wholly-owned subsidiary of the Company with
and into Focal, Inc. ("Focal") pursuant to the terms of the Agreement and
Plan of Merger dated as of April 25, 2001 by and among the Company, Focal and
Sammy Merger Corp. These options were originally granted to employees and
directors under Focal's 1992 Incentive Stock Plan, 1999 Stock Incentive Plan
and 1997 Director Option Plan and are currently exercisable upon the same
terms and conditions as provided in the Focal plan under which the options
were issued, except that the assumed option is exercisable for the number of
shares of Genzyme Biosurgery Division common stock equal to the number of
shares of Focal common stock that were issuable upon exercise of the option
immediately before the merger multiplied by 0.1545 at a per share exercise
price equal to the exercise price for which the option was exercisable
immediately before the merger divided by 0.1545 (the "Exercise Terms").

     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 authorization, issuance and sale of the Shares. We
have examined all such documents as we consider necessary to enable us to render
this opinion.

     Based upon the foregoing, we are of the opinion that when issued in
accordance with the Exercise Terms, the Shares will be duly authorized, validly
issued, fully paid and nonassessable.

     We hereby consent to the filing of this opinion as a part of the
Registration Statement.


                                   Very truly yours,

                                   /s/ Palmer & Dodge LLP

                                   Palmer & Dodge LLP