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SECURITIES AND EXCHANGE COMMISSIONWashington, D.C. 20549

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FORM 10-Q/A
AMENDMENT NO. 1

|ý                                   | QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|----------------------------------- | ---------------------------------------------------------------------------------------
|For the Quarter Ended June 30, 2002

Commission File Number 0-21481

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TRANSKARYOTIC THERAPIES, INC.(Exact name of registrant as specified in its charter)

|Delaware(State or other jurisdiction of
incorporation or organization)           |  | 04-3027191(I.R.S. Employer
Identification No.)
|-------------------------------------------------------------------------------- |  | ----------------------------------------------
|700 Main Street
Cambridge, Massachusetts(Address of principal executive offices) |  | 02139(Zip Code)                               
|Registrant's telephone number, including area code:(617) 349-0200               

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Indicate
by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the
preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.

Yes ý    No o

At
July 31, 2002, there were 34,811,022 shares of Common Stock, $.01 par value, outstanding.

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Explanatory Note

We are filing this amendment no. 1 to our Quarterly Report on Form 10-Q for the period ended June 30, 2002 on this
Form 10-Q/A solely to refile Exhibit 10.31.

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SIGNATURES

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
thereunto duly authorized.

|                        |  | TRANSKARYOTIC THERAPIES, INC.
|----------------------- |  | -----------------------------
|Date: December 19, 2002 |  | By:                          

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CERTIFICATIONS

I,
Richard F. Selden, certify that:

(1)
I have reviewed this quarlerly report as amended by amendment no.1 to the quarterly report on Form 10-Q/A of Transkaryotic Therapies, Inc.; and

(2)
Based on my knowledge, this quarterly report, as amended, does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements
made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this quarterly report.

|Dated: December 19, 2002 | /s/RICHARD F. SELDENRichard F. Selden President and Chief Executive Officer
|------------------------ | ---------------------------------------------------------------------------

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I, Daniel E. Geffken, certify that:

(1)
I have reviewed this quarterly report as amended by amendment no.1 to the quarterly report on Form 10-Q/A of Transkaryotic Therapies, Inc.; and

(2)
Based on my knowledge, this quarterly report, as amended, does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements
made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this quarterly report.

|Dated: December 19, 2002 | /s/DANIEL E. GEFFKENDaniel E. Geffken Senior Vice President, Finance and
Chief Financial Officer
|------------------------ | ------------------------------------------------------------------------------------------------

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EXHIBIT INDEX

|10.31# |  | License Agreement, dated June 7, 2002, by and between Cell Genesys, Inc. and the Registrant
|------ |  | -------------------------------------------------------------------------------------------

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