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EXHIBIT 99.1

CONTACT:
Justine E. Koenigsberg
Director, Corporate Communications
(617) 349-0271

FOR IMMEDIATE RELEASE

TKT ANNOUNCES $88 MILLION PUBLIC OFFERING OF COMMON STOCK

Cambridge, MA, June 25, 2001 -- Transkaryotic Therapies, Inc. (Nasdaq: TKTX)
today announced the public offering of 3,100,000 shares of its common stock at a
purchase price of $28.50 per share. All of the shares offered were offered by
TKT. The Company intends to use the net proceeds from the sale of the common
stock for general corporate purposes, including building its sales and marketing
capabilities for its Niche Protein(TM) products, expanding clinical trials and
funding preclinical testing and other research and development programs. SG
Cowen Securities Corporation acted as underwriter for the common stock offering.
In addition, TKT has granted the underwriters an option to purchase up to
465,000 additional shares of common stock to cover overallotments.

Copies of the prospectus relating to this offering of common stock may be
obtained from the underwriters at the Prospectus Department of SG Cowen
Securities Corporation, One Financial Square, 27th Floor, New York, NY 10005,
Attention: Maryann Moccia.

A registration statement relating to these securities has been filed with and
declared effective by the Securities and Exchange Commission. This press release
shall not constitute an offer to sell or the solicitation of an offer to buy nor
shall there be any sale of these securities in any state in which such offer,
solicitation or sale would be unlawful prior to registration or qualification
under the securities laws of any such state.

Transkaryotic Therapies, Inc. (TKT) is a biopharmaceutical company dedicated to
the development and commercialization of products based on its three proprietary
development platforms: Gene-Activated(R) proteins, Niche Protein(TM) products,
and Gene Therapy. The Company's gene activation technology is a proprietary
approach to the large-scale production of therapeutic proteins, which does not
require the cloning of genes and their subsequent insertion into non-human cell
lines. TKTis Niche Protein product platform is based on protein replacement for
the treatment of rare genetic diseases, a group of disorders characterized by
the absence of certain metabolic enzymes. The Company's Gene Therapy technology,
known as Transkaryotic Therapy(TM), is focused on the commercialization of
non-viral, ex vivo gene therapy products for the long-term treatment of chronic
protein deficiency states.

Gene-Activated(R) is a registered trademark and Niche Protein(TM), TKT(TM), and
Transkaryotic Therapy(TM) are trademarks of Transkaryotic Therapies, Inc.