8-K

                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                                    FORM 8-K

                                 CURRENT REPORT

                     Pursuant to Section 13 or 15(d) of the
                         Securities Exchange Act of 1934


Date of Report (Date of Earliest Event Reported):            MAY 18, 2000
                                                     -------------------------

                          TRANSKARYOTIC THERAPIES, INC.
          ------------------------------------------------------------
             (Exact Name of Registrant as Specified in its Charter)



                                    Delaware
          ------------------------------------------------------------
                 (State or Other Jurisdiction of Incorporation)

            000-21481                                 04-3027191
    ------------------------                ---------------------------------
    (Commission File Number)                (IRS Employer Identification No.)


    195 Albany Street, Cambridge, Massachusetts               02139
    ------------------------------------------------------------------
    (Address of Principal Executive Offices)                (Zip Code)


                                 (617) 349-0200
          ------------------------------------------------------------
               Registrant's Telephone Number, Including Area Code


                                 Not Applicable
          ------------------------------------------------------------
          (Former Name or Former Address, if Changed Since Last Report)





Item 5.  Other Events.
         -------------

         On May 18, 2000, Transkaryotic Therapies, Inc. (the "Registrant")
and investment funds affiliated with E.M. Warburg, Pincus & Co., L.L.C.
(collectively, "Warburg Pincus") executed a Stock Purchase Agreement (the
"Purchase Agreement"), pursuant to which Warburg Pincus will purchase 10,000
shares of the Registrant's Series A Convertible Preferred Stock, $0.01 par
value per share, for an aggregate price of $100,000,000. Under the terms of
the Purchase Agreement, the 10,000 shares of Series A Convertible Preferred
Stock shall convert into approximately 3,570,000 shares of the Registrant's
common stock, $0.01 par value per share, at a conversion price of $28.00 per
share. The transactions contemplated by the Agreement are subject to U.S.
government approval under the Hart-Scott-Rodino Antitrust Improvements Act of
1976.

         The full text of the Registrant's press release issued in connection
with the foregoing is filed as Exhibit 99.1 to this Current Report on Form
8-K and is incorporated herein by reference.

Item 7.  Financial Statements and Exhibits.
         ----------------------------------

(c)      Exhibits.

99.1 The Registrant's Press Release dated May 19, 2000.



                                     - 2 -





                                    SIGNATURE


Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

Date: May 19, 2000

                                    TRANSKARYOTIC THERAPIES, INC.
                                             (Registrant)



                                    By: /s/ Daniel E. Geffken
                                        -----------------------------
                                    Daniel E. Geffken
                                    Vice President, Finance and Chief
                                    Financial Officer



                                     - 3 -





                                  EXHIBIT INDEX

Exhibit Number                Description
- --------------                -----------

99.1                          The Registrant's Press Release dated May 19, 2000.




                                     - 4 -

EX-99.1

                                                                    Exhibit 99.1

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

FOR IMMEDIATE RELEASE

                 TKT ANNOUNCES $100 MILLION PRIVATE PLACEMENT OF
                       PREFERRED STOCK WITH WARBURG PINCUS

CAMBRIDGE, MA, MAY 19, 2000 -- Transkaryotic Therapies, Inc. (Nasdaq: TKTX)
today announced that investment funds affiliated with E.M. Warburg, Pincus &
Co., LLC ("Warburg Pincus"), a private equity investment firm, have signed a
definitive agreement to purchase $100,000,000 of newly issued convertible
preferred stock. Under the agreement, Warburg Pincus will purchase preferred
stock convertible into approximately 3,570,000 shares of the Company's common
stock at a conversion price of $28.00 per share. The transaction is subject to
regulatory approval under the Hart-Scott-Rodino Antitrust Improvements Act of
1976.

This convertible preferred stock has not been registered under the Securities
Act of 1933, as amended, and may not be offered or sold in the United States
absent registration or an applicable exemption from registration requirements.

TKT intends to use proceeds of this offering for the expansion of programs in
its Niche Protein(TM) platform and other general corporate purposes. TKT's Niche
Protein platform is focused on developing protein replacement products to treat
patients suffering from rare genetic disorders such as Fabry disease, Hunter
syndrome, and Gaucher disease. TKT intends to develop and commercialize a series
of protein replacement products aimed at reducing symptoms and potentially
reversing progression in these debilitating and often life threatening rare
diseases.

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(TM) 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. TKT's 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.

Warburg Pincus is a major global private equity investment firm that has
sponsored eight private equity funds since 1971. To date, these funds have
invested more than $9 billion in over 360 companies across a broad range of
industries. The firm's most recent fund, Warburg Pincus Equity Partners, L.P.,
closed in 1998 with subscribed capital of $5 billion. Warburg Pincus has
considerable experience investing in the biopharmaceuticals industry, having
invested over $600 million in more than 30 biotechnology and specialty
pharmaceutical companies. More information is available at www.warburg
pincus.com.
                                   -- more --






Transkaryotic Therapies, Inc.
$100 Million Private Placement of Preferred Stock
May 19, 2000
Page 2


This press release contains forward-looking statements that involve a number of
risks and uncertainties. For this purpose, any statements contained herein that
are not statements of historical fact may be deemed to be forward-looking
statements. Without limiting the foregoing, the words, "believes,"
"anticipates," "plans," "expects," "intends," and similar expressions are
intended to identify forward-looking statements. Important factors that could
cause actual results to differ materially from the expectations described in
these forward-looking statements are set forth under the caption "Certain
Factors That May Affect Future Results" in the Company's Annual Report on Form
10-K for the year ended December 31, 1999 which is on file with the Securities
and Exchange Commission and incorporated herein by reference. These important
factors include risks as to whether TKT's products will advance in the clinical
trials process, the timing of such clinical trials, whether the clinical trial
results will warrant continued product development, and whether the Company's
products will receive approval from the U.S. Food and Drug Administration or
equivalent regulatory agencies, and, if such products receive approval, whether
they will be successfully marketed; the results of any patent litigation in
which the Company is involved or may become involved; competition; and the
Company's dependence on collaborators.

GENE-ACTIVATED(TM), NICHE PROTEIN(TM), TKT(TM), AND TRANSKARYOTIC THERAPY(TM)
ARE TRADEMARKS OF TRANSKARYOTIC THERAPIES, INC. PLEASE VISIT OUR WEB SITE AT
WWW.TKTX.COM FOR ADDITIONAL INFORMATION ABOUT TRANSKARYOTIC THERAPIES, INC.
                                       ###