Filed by Genzyme Corporation (Commission File No. 000-14680)
                           pursuant to Rule 425 under the Securities Act of 1933

   Subject Company: GelTex Pharmaceuticals, Inc. (Commission File No. 000-26872)


[GENZYME LOGO]                                   [GELTEX LOGO]


FOR GELTEX:                                      FOR GENZYME:
Mark Skaletsky                                   Sally Curley (investors)
781-434-3500                                     617-591-7140
Paul Mellett                                     Bo Piela (media)
781-434-3484                                     617-252-7785


FOR IMMEDIATE RELEASE
November 9, 2000

 GENZYME AND GELTEX ANNOUNCE REGISTRATION STATEMENT FOR GENZYME'S ACQUISITION OF
                        GELTEX DECLARED EFFECTIVE BY SEC

     CAMBRIDGE and WALTHAM, Mass.---Genzyme Corp. and GelTex Pharmaceuticals,
Inc. (Nasdaq: GELX) announced today that the Securities and Exchange Commission
(SEC) has declared effective the registration statement for Genzyme's
acquisition of GelTex. Once the merger is effective, all of GelTex's assets,
liabilities and operations will be allocated to Genzyme General (Nasdaq: GENZ),
a division of Genzyme Corp.

     A proxy statement/prospectus will be mailed on November 13 to GelTex
stockholders. The record date for GelTex shareholders was October 24, 2000.
GelTex expects to hold a special meeting of its shareholders on December 13,
2000 at GelTex's offices, 153 Second Ave., Waltham, to obtain the required
approval. Upon shareholder approval, the transaction is expected to close before
the end of the year.


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Genzyme and GelTex Announce Registration Statement for Genzyme's Acquisition
of GelTex Declared Effective by SEC--page 2



         With the acquisition, Genzyme General will have access to two
patent-protected, marketed products--Renagel(R) brand sevelamer hydrochloride
and WelChol(TM) brand colesevelam hydrochloride--along with a significant
pipeline of promising products and a proven and productive polymer technology
development team. Renagel is a rapidly growing product used in the treatment of
patients with end-stage renal disease undergoing hemodialysis. WelChol is a new
cholesterol-lowering agent that was launched in September 2000 by Sankyo Pharma,
Inc.

TERMS OF MERGER AGREEMENT

         Under the terms of the agreement, GelTex shareholders can elect to
receive 0.7272 of a share of Genzyme General Division common stock or $47.50 in
cash for each GelTex share owned, subject to proration to maintain the cash
portion of the total consideration at 50 percent, or approximately $509 million.

         The boards of directors of Genzyme Corp. and GelTex have approved the
transaction, which is subject to clearance under the Hart-Scott-Rodino
Anti-Trust Improvements Act. The transaction will require the approval of GelTex
shareholders, and is subject to customary closing conditions.

         Genzyme General develops and markets therapeutic products and
diagnostic products and services. Genzyme General has three therapeutic products
on the market and a strong pipeline of products in development focused on the
treatment of genetic disorders and other chronic and debilitating diseases.
Genzyme General is a division of the biotechnology company, Genzyme Corporation.


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Genzyme and GelTex Announce Registration Statement for Genzyme's Acquisition
of GelTex Declared Effective by SEC--page 3



         GelTex develops and markets non-absorbed polymer drugs that bind and
eliminate targeted substances within the gastrointestinal tract. In addition,
GelTex is developing small-molecule pharmaceuticals consisting of novel
polyamine analogues and metal chelators.

This press release contains forward-looking statements, including statements
about the anticipated consummation, timing and benefits of the merger, the value
of the merger consideration, the nature of the merger, and expectations
concerning GelTex's product candidates and polymer technology. Actual results
may materially differ due to numerous factors, including without limitation
conditions in the financial markets relevant to the proposed merger, the
likelihood of receipt of regulatory and other approvals of the merger, the
actual efficacy and safety of products, the content and timing of submissions to
and decisions by regulatory authorities, the ability of Genzyme to retain
GelTex's development team, the ability of the development team to continue to
develop viable drug candidates, and the risks and uncertainties described in the
information included under the caption "Risk Factors" in the proxy
statement/prospectus we filed with the SEC on November 1, 2000, and in Genzyme
and GelTex's reports filed with the Securities and Exchange Commission under the
Securities Exchange Act of 1934, as amended, including without limitation
Exhibit 99.2 to Genzyme's Annual Report on Form 10-K for the year ended December
31, 1999, as amended. Genzyme General Division Common Stock is a series of
common stock of Genzyme Corporation. Therefore, holders of Genzyme General
Division Common Stock are subject to all of the risks and uncertainties
described in the aforementioned reports.

This material is not a substitute for the proxy statement/prospectus Genzyme and
GelTex have filed with the Securities and Exchange Commission. Investors are
urged to read that document because it contains important information. The proxy
statement/prospectus and other documents filed by Genzyme and GelTex with the
SEC and incorporated by reference into the proxy statement/prospectus are
available free of charge at the SEC's website (www.sec.gov) and from Genzyme or
GelTex.

GelTex, its directors, and certain of its executive officers may be considered
participants in the solicitation of proxies in connection with the merger.
Information concerning GelTex's directors and executive officers can be found in
the documents filed by GelTex with the SEC. Certain directors and executive
officers of GelTex may have direct or indirect interests in the merger due to
securities holdings, vesting of options, and rights to severance payments if
their employment terminates following the merger. In addition, directors and
officers, after the merger, will be indemnified by Genzyme, and benefit from
insurance coverage for liabilities that may arise from their service as
directors and officers of GelTex prior to the merger. Additional information
regarding the participants in the solicitation is contained in the proxy
statement/prospectus.

                                      # # #

           PLEASE SEE PACKAGE INSERT FOR FULL PRESCRIBING INFORMATION.


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Genzyme and GelTex Announce Registration Statement for Genzyme's Acquisition
of GelTex Declared Effective by SEC--page 4



Genzyme's releases are available on the World Wide Web at
http://www.genzyme.com. They are also available from Genzyme's fax-on-demand
service at 1-800-436-1443 within the United States or 1-201-521-1080 outside the
United States.

GelTex's press releases are available at http://www.geltex.com