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EXHIBIT 10.37

                              EMPLOYMENT AGREEMENT

    AGREEMENT, dated as of May 18, 2000, between Transkaryotic Therapies, Inc.,
a Delaware corporation (the "Company"), and Michael J. Astrue (the "Executive").

    1. EMPLOYMENT. The Company hereby employs the Executive and the Executive
hereby accepts employment with the Company upon the terms and conditions herein
set forth.

    2. DUTIES. The Executive shall be engaged as a full-time employee to act as
the Company's Senior Vice President, Administration and General Counsel, and
shall report to the Company's Founder and Chief Executive Officer. The Executive
shall perform the duties consistent with such position as the Founder and Chief
Executive Officer shall from time to time reasonably designate. The Executive
shall devote his entire time, attention and energies to the business of the
Company and shall not engage in any other business activity or activities,
whether or not such business activity is pursued for gain, profit or other
pecuniary advantage that, in the judgment of the Company, may conflict with the
proper performance of the Executive's duties under this Agreement.
Notwithstanding the foregoing, (a) with respect to businesses which do not
compete with the Company, the Executive may invest his personal or family assets
in such form or manner as will not require any services on the part of the
Executive in the operation of the affairs of the companies in which such
investments are made and in which his participation is solely that of an
investor, and (b) the Executive may purchase securities in any corporation whose
securities are regularly traded in recognized securities markets, provided that
such investments shall not result in his collectively owning beneficially at any
time one percent (1%) or more of the equity securities of any corporation
engaged in a business competitive to that of the Company.

         3. COMPENSATION.

         (a) BASE SALARY. For services rendered under this Agreement, the
         Company shall pay the Executive an annual salary of $250,000 (the "Base
         Salary"), payable (after deduction of applicable withholding for
         Federal and state income and payroll taxes) in equal semi-monthly
         installments. The Company may review the Executive's compensation
         annually and make such increases to the Base Salary as the Company
         determines are merited, based upon the Executive's performance and


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         consistent with the Company's compensation policies as established by
         the Compensation Committee of the Company's Board of Directors. Any
         such increase in annual Base Salary shall be communicated to the
         Executive shortly after the January meeting of the Board of Directors
         and shall be made effective on the first day of January each year.

         (b) BONUS. The Chief Executive Officer and the Executive shall
         establish objective performance goals for the Executive for such
         calendar year. Upon the attainment of such performance goals, but
         subject to the overall performance of the Company during such year, the
         Executive may be entitled to a bonus targeted at forty percent (40%) of
         base compensation, as determined by the Compensation Committee of the
         Company's Board of Directors. Within thirty (30) days after the close
         of each such calendar year, the Company shall evaluate the attainment
         of the performance goals for such calendar year and determine the
         amount of any performance bonus payable hereunder. Any such performance
         bonus shall be payable within ninety (90) days after the calendar year
         to which it relates.

         (c) FRINGE BENEFITS. In addition to Base Salary and Bonus payments
         under Sections 3(a), (b), and (c) above, the Executive shall be
         eligible for and participate in such fringe benefits, in accordance
         with the terms of each such benefit, as shall be generally provided to
         executives of the company, including incentive compensation, the
         Company's 401(k) Plan, health and dental insurance, and any retirement
         programs, stock options plans or employee stock purchase plans which
         may be adopted from time to time during the term hereof by the Company.
         Nothing herein contained shall be deemed to preclude the Company from
         granting such additional compensation or benefits to the Executive as
         it shall in its sole discretion determine.

         (d) STOCK OPTIONS. Upon authorization by the Company's Board of
         Directors or Compensation Committee, the Company will promptly grant
         the Executive under the Company's 1993 Long-Term Incentive Plan (the
         "Plan") a nonstatutory stock option to purchase an aggregate of one
         hundred fifty thousand (150,000) shares of the Common Stock of the
         Company, par value $.01 per share, at a purchase price of twenty-seven
         and 625/100 dollars ($27.625) per share. Of such options, 12,000 will
         vest immediately on May 18, 2000, with the remaining 138,000 vesting
         annually for a period of six (6) years on the anniversary date of this
         Agreement in installments of 23,000 options each. Such option shall be
         exercisable during the ten (10) year period following its date of
         vesting and shall be subject to all the terms and conditions of the
         Plan


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         and the Company's standard form of Stock Option Agreement, copies
         of which have been delivered to the Executive separately.

         4. VACATION. During the term of this Agreement, the Executive shall be
entitled to fifteen (15) annual vacation days accrued at the rate of 1.25 days
per month.

         5. SICK LEAVE. During the term of this Agreement, the Executive shall
be entitled to sick leave consistent with the Company's customary sick leave
policy.

         6. EXPENSES. During the term of this Agreement, the Company shall
reimburse the Executive in accordance with the Company's customary policies for
all reasonable out-of-pocket expenses incurred by the Executive in connection
with the business of the Company and in performance of his duties under this
Agreement upon the Executive's presentation to the Company of an itemized
accounting of such expenses with reasonable supporting data.

         7.       TERM.

         (a) The Executive's employment under this Agreement shall commence on
         May 18, 2000 (the "Commencement Date") and shall continue until
         terminated by the Company as provided in this Section 7(a) or by the
         Executive as provided in Section 7(c) below. The Company may, at its
         election, terminate the obligations of the Company under this Agreement
         as follows:

                  (i) Upon at least sixty (60) days' prior written notice if the
                  Executive becomes physically or mentally incapacitated or is
                  injured so that he is unable to perform the services required
                  of him hereunder and such inability to perform continues for a
                  period in excess of six (6) months and is continuing at the
                  time of such notice; or

                  (ii) For "Cause" upon prior written notice of such termination
                  to the Executive. For purposes of this Agreement, the Company
                  shall have "Cause" to terminate its obligations hereunder upon
                  (a) the Company's determination that the Executive has ceased
                  or failed to substantially perform his duties hereunder (other
                  than as a result of his incapacity due to physical or mental
                  illness or injury), and at least thirty (30) days' prior
                  written notice to the Executive, (b) the Executive's death,
                  (c) the Company's determination that the Executive has engaged
                  or


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                  is about to engage in conduct materially injurious to the
                  Company, (d) the Executive's having been convicted of a
                  felony, or (e) the Executive's participation in activities
                  proscribed by the provisions of Sections 2, 9, or 11 hereof or
                  material breach of any of the other covenants herein; or

                  (iii) Without Cause upon at least sixty (60) days' prior
                  written notice of such termination to the Executive.

         (b) If, subsequent to six (6) months of the date the Executive's
         employment hereunder commences, this Agreement is terminated pursuant
         to Section 7(a)(i) above, subject to Section 11(d) below, the Executive
         shall receive severance pay until the fourth anniversary of the date
         hereof at the rate of one hundred percent (100%) of Base Salary,
         reduced by applicable payroll taxes and further reduced by the amount
         received by the Executive during such period under any Company
         maintained disability insurance policy or plan or under Social Security
         or similar laws. Such severance payments shall be paid periodically to
         the Executive as provided in Section 3(a) for the payment of Base
         Salary. If this Agreement is terminated at any time pursuant to Section
         7(a)(ii) above, the Executive shall receive no severance pay. If this
         Agreement is terminated pursuant to Section 7(a)(iii) above, the
         Executive shall receive severance pay, for a period of twelve (12)
         months from and after such termination, equal to the Base Salary less
         the amount, if any, earned by the Executive during such twelve (12)
         month period, whether as salary, consulting fees, deferred payments or
         other direct or indirect compensation. Such severance payments (less
         applicable withholding and payroll taxes) shall be paid periodically to
         the Executive as provided in Section 3(a) for the payment of Base
         Salary.

         (c) The Executive may terminate his employment under this Agreement
         upon breach by the Company or for Good Reason. Termination of the
         Executive's employment for "breach" shall mean in the event that the
         Company fails to perform, in any material respect, its obligations
         under the Agreement, after written notice to the Company setting forth
         in reasonable detail the nature of such breach, if such breach remains
         uncured for a period of 90 days following such notice to the Company.
         Termination of the Executive's employment for "Good Reason" shall only
         mean termination based on (i) a substantial diminution in the
         responsibilities, duties, and powers of the Executive including,
         without limitation, the Executive ceasing to be the Senior Vice
         President, Administration and General Counsel of the Company; and/or
         (ii) the relocation of the Executive's present office


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         location to an area more than 100 miles from the metropolitan Boston
         area. In the event of termination of employment pursuant to this
         paragraph (c), the Company shall pay to the Executive severance pay for
         a period of twelve (12) months in an amount equal to (x) 100% of the
         Executive's Base Salary immediately prior to such termination; plus,
         (y) any bonus payment for the fiscal year preceding the year in which
         such termination occurs that was earned but not paid at the date of
         such termination. The Executive shall not be required to mitigate the
         amount of any payment provided for in this paragraph (c) by seeking
         other employment or otherwise, but the amount of any payment or benefit
         provided for in this paragraph (c) shall be reduced by an amount equal
         to any compensation earned by the Executive as a result of employment
         with another employer after termination of employment with the Company,
         or otherwise.

         (d) The Executive may terminate his employment under this Agreement for
         any reason upon at least sixty (60) days' prior written notice. In the
         event of any such termination of employment pursuant to this paragraph
         (d) (excluding any termination of employment paragraph (c) above), the
         Executive shall not be entitled to any severance payments.

         8. REPRESENTATIONS. The Executive hereby represents to the Company that
(a) he is legally entitled to enter into this Agreement and to perform the
services and other obligations contemplated herein; (b) he has, and throughout
the term of this Agreement will continue to have, the full right, power and
authority, subject to no rights of third parties, to grant to the Company the
rights contemplated by Section 10 hereof; and (c) he is not subject to any
agreement, rule, regulation or policy of any university, research institution or
other third party inconsistent with the foregoing representations.

         9. DISCLOSURE OF INFORMATION.

         (a) The Executive recognizes and acknowledges that the Company's trade
         secrets, know-how and proprietary processes as they may exist from time
         to time (including, without limitation, information regarding methods,
         cultures, vectors, plasmids, synthesis techniques, nucleic acid
         sequences, purification techniques and assay procedures) as well as the
         Company's confidential business plans and financial data are valuable,
         special and unique assets of the Company's business, access to and
         knowledge of which are essential to the performance of the Executive's
         duties hereunder. The Executive shall not, during or after the term of
         his employment by the Company, in whole or in part,


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         disclose such secrets, know-how, processes, business plans or financial
         data to any person, firm, corporation, association or other entity for
         any reason or purpose whatsoever, nor shall the Executive make use of
         any such property for his own purposes or for the benefit of any
         person, firm, corporation or other entity (except the Company) under
         any circumstances during or after the term of his employment, provided
         that after the term of his employment, these restrictions shall not
         apply to such secrets, know-how, and processes which the Executive can
         establish by competent proof:

                  (i) were known, other than under binder of secrecy, to the
                  Executive prior to his employment by the Company;

                  (ii) were passed into the public domain prior to or after
                  their development by or for the Company, other than through
                  acts or omissions attributable to the Executive; or

                  (iii) were subsequently obtained, other than under binder of
                  secrecy, from a third party not acquiring the information
                  under an obligation of confidentiality from the disclosing
                  party.

         (b) Upon termination of his employment hereunder, the Executive shall
         promptly turn over to the Company all originals and copies which he may
         have of any of the Company's confidential information described in this
         Section 9.

         10. INTELLECTUAL PROPERTY. The Executive hereby sells, transfers, and
assigns to the Company, or to any person or entity designated by the Company,
the entire right, title, and interest of the Executive in and to all inventions,
ideas, discoveries, and improvements (including, without limitation, all
microorganisms, strains or cultures) whether patented or unpatented, and
copyrightable material made or conceived by the Executive, solely or jointly,
during the term hereof, which arise out of research or other activities
conducted by, for or under the direction of the Company, whether or not
conducted at the Company's facilities, or which relate to methods, apparatus,
designs, products, processes or devices, sold, leased, used or under
consideration or development by the Company. The Executive acknowledges that all
copyrightable materials developed or produced by the Executive within the scope
of his employment constitute works made for hire. The Executive shall
communicate promptly and disclose to the Company, in such form as the Company
may reasonably request, all information, details, and data pertaining to any
such inventions, ideas, discoveries, and improvements; and the Executive shall
execute and deliver to the Company such formal transfers and assignments and
such other papers and documents

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and shall give such testimony as may be necessary or required of the Executive
to permit the Company or any person or entity designated by the Company to file
and prosecute patent applications and, as to copyrightable material, to obtain
copyrights thereof. Any such invention, idea, discovery or improvement disclosed
by the Executive within one (1) year following the termination of this Agreement
shall be deemed to fall within the provisions of this Section 10 unless proved
to have been first conceived and made following such termination.

         11. COVENANTS NOT TO COMPETE OR INTERFERE.

         (a) Subject to Section 11(b) below, during the term of this Agreement
         and the period ending twenty-four (24) months from and after the
         termination of the Executive's employment hereunder, the Executive
         shall not engage in any business (whether as an officer, director,
         owner, employee, partner, consultant, advisor or other direct or
         indirect participant) engaged in the development of non-viral gene
         therapy and/or gene targeting and/or gene activation methods and/or the
         sale of products or rendering of services related to non-viral gene
         therapy and/or gene targeting and/or gene activation and/or to any
         other activities which directly compete with the Company's business
         activities. This Agreement shall not be construed to restrict the
         Executive's right to be employed as a faculty member of any university
         or employee of any nonprofit agency or foundation after any termination
         of this Agreement where this covenant not to compete shall continue to
         be in effect. During the period in which this covenant not to compete
         is in effect the Executive also shall not interfere with, disrupt or
         attempt to disrupt the relationship, contractual or otherwise, between
         the Company and any customer, supplier, lessor, lessee, employee,
         consultant, research partner or investor of the Company.

         (b) If this Agreement is terminated by the Company pursuant to Section
         7(a)(iii) above, the provisions of the first sentence of Section 11(a)
         shall apply until twelve (12) months from and after such termination.

         (c) It is the desire and intent of the parties that the provisions of
         this Section 11 shall be enforced to the fullest extent permissible
         under the laws and public policies applied in each jurisdiction in
         which enforcement is sought. Accordingly, if any particular Subsection
         or portion of this Section 11 shall be adjudicated to be invalid or
         unenforceable, this Section 11 shall be deemed amended to delete
         therefrom the portion thus adjudicated to be invalid or unenforceable,


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         such deletion to apply only with respect to the operation of this
         Section in the particular jurisdiction in which such adjudication is
         made.

         (d) In the event of any breach of the provisions of this Section 11 by
         the Executive, any and all rights of the Executive to receive severance
         payments under Section 7(b) above shall automatically terminate.

         12. INJUNCTIVE RELIEF. If there is a breach or threatened breach of the
provisions of Section 9, 10, or 11 of this Agreement, the Company shall be
entitled to an injunction, without bond, restraining the Executive from such
breach. Nothing herein shall be construed as prohibiting the Company from
pursuing any other remedies for such breach or threatened breach.

         13. INSURANCE. The Company may, at its election and for its benefit,
insure the Executive against accidental loss or death, and the Executive shall
submit to such physical examinations and supply such information as may be
required in connection therewith.

         14. NOTICES. Any notice required or permitted to be given under this
Agreement to the Executive shall be sufficient if in writing and if sent by
certified or registered mail to his residence, or in the case of the Company, to
Transkaryotic Therapies, Inc., 195 Albany Street, Cambridge, MA 02139,
Attention: Chief Executive Officer, or to such other offices or addresses as the
company shall designate from time to time in writing to the Executive. Any such
notice shall be effective on the earlier of (a) the date on which it is
personally delivered or (b) three (3) days after it is deposited in the United
States mails, postage prepaid.

         15. WAIVER OF BREACH. A waiver by the Company or the Executive of a
breach of any provision of this Agreement by the other party shall not operate
or be construed as a waiver of any subsequent breach by the other party.

         16. GOVERNING LAW. This Agreement shall be governed by and construed
and enforced in accordance with the internal laws of the Commonwealth of
Massachusetts.

         17. ASSIGNMENT. This Agreement may be assigned, without the consent of
the Executive, by the Company to any person, partnership, corporation or other
entity which succeeds to the business of the Company or which has purchased
substantially all the assets of the Company, provided such assignee assumes all
the liabilities of the Company hereunder.


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         18. ENTIRE AGREEMENT. This Agreement contains the entire agreement of
the parties and supersedes any prior understandings or agreements between the
Executive and the Company. This agreement may be changed only by an agreement in
writing signed by the party against whom enforcement of any waiver, change,
modification, extension or discharge is sought.

         IN WITNESS WHEREOF, the parties have executed this Employment Agreement
as of the date first above written.

                                             TRANSKARYOTIC THERAPIES, INC.

                                              By: /s/ RICHARD F SELDEN
                                                  --------------------
                                                   Richard F Selden, M.D., Ph.D.
                                                   Founder and Chief Executive
                                                   Officer

                                                   /s/ MICHAEL J. ASTRUE
                                                   ---------------------
                                                   Michael J. Astrue

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