Document:

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                                                                   EXHIBIT 10.16

                                    SUBLEASE

     This instrument dated as of September 21, 1996, is a Sublease between
GENZYME CORPORATION, a Massachusetts corporation ("Sublessor"), and DYAX CORP.,
a Delaware corporation ("Sublessee").

     The parties to this instrument hereby agree with each other as follows:

                                    ARTICLE I

                      SUMMARY OF BASIC SUBLEASE PROVISIONS
                      ------------------------------------

1.1  BASIC DATA

ALL CAPITALIZED TERMS USED HEREIN SHALL HAVE THE MEANINGS ASCRIBED TO THEM IN
THE PRIME LEASE (hereinafter defined) UNLESS OTHERWISE DEFINED HEREIN.

Commencement Date:          September 21, 1996.

Sublessor:                  Genzyme Corporation

Present Mailing Address
of Sublessor:               One Kendall Square, Building 1400
                            Cambridge, Massachusetts 02139

Sublessee:                  Dyax Corp.

Present Mailing Address
of the Sublessee:           One Kendall Square, Building 600
                            Cambridge, Massachusetts 02139

Permitted Uses:             Offices, research, development, laboratories,
                            manufacturing, storage, marketing and sales of
                            biologically derived products in connection with
                            biological and chemical research.

Premises:                   16,183 rentable square feet of office and laboratory
                            space located on the fifth floor of the building
                            known as Building 600, One Kendall Square,
                            Cambridge, Massachusetts (the "Building"), as
                            approximately shown on the sketch attached hereto
                            as Exhibit A.  The Premises demised under this
                            Sublease comprise a portion of the Leased Premises
<PAGE>

                            (as defined in the Prime Lease) leased to Sublessor
                            by Prime Lessor under the Prime Lease (as defined
                            below).

Prime Lease:                That certain lease, dated as of December 20, 1988,
                            between the Trustees of Old Kendall Realty Trust,
                            as lessor (the "Prime Lessor"), and Sublessor, as
                            lessee as most recently amended by a Third
                            Amendment dated March 8, 1996; a copy of the
                            pertinent provisions of the Prime Lease is attached
                            hereto as Exhibit B.

Rent:                       $614,954 per annum ($38 per sq. ft.)/$51,246.16
                            per month [BUT SEE Section 6.1(e) below for
                            Sublessee's rights for a limited "rent free" period
                            for the "Expansion Space" portion of the Premises].

Sublease Term or Term:      Beginning on the Commencement Date and expiring
                            on September 30, 1998.

                                   ARTICLE II

                                    PREMISES
                                    --------

2.1  SUBLEASE OF PREMISES

     Sublessor hereby leases to Sublessee, and Sublessee hereby accepts and
leases from Sublessor, upon and subject to the terms and provisions of the Prime
Lease, all of Sublessor's right, title and interest in and to the Premises for
the Sublease Term. As appurtenant to the Premises, Sublessee shall be entitled
to the appurtenant rights set forth in clauses (a) and (b) of Section 2 of the
Prime Lease, subject in all events to the Prime Lessor's rights reserved and
excepted in such clauses.

2.2  PRIME LEASE

2.2.1 Sublessor hereby represents and warrants that: (i) Sublessor is lessee
under the Prime Lease and has the full right to enter into this Sublease; (ii)
the Prime Lease is in full force and effect and that Sublessor has submitted to
Sublessee a true and complete copy of those portions of the Prime Lease that are
pertinent to Sublessee's rights and obligations under this Sublease; (iii)
Sublessor has not received any notice of default thereunder from Prime Lessor,
nor is Sublessor aware of any default thereunder by Sublessor or Prime Lessor or
of any event or condition which, but for the passage of time or the giving of
notice or both, would constitute a default thereunder by Sublessor or Prime
Lessor; and (iv) to Sublessor's knowledge and belief, the Premises and their
electrical, mechanical, plumbing, heating, ventilating, and air conditioning
systems and all fixtures and equipment built into the Premises are in good
working order and repair. Sublessee warrants and acknowledges that it has
reviewed the Prime Lease and is satisfied with the arrangements therein
reflected. Sublessee also warrants and acknowledges that it is satisfied with
the present condition of the Premises (which Sublessee

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takes "as is" without any representation or warranty by Sublessor regarding the
condition of the Premises [except as set forth in Section 2.2.1 (iv) above] or
the fitness of the Premises for any particular use, and without obligation of
any kind on Sublessor to make any repairs or improvements thereto), and with
Sublessee's ability to use the Premises on the terms herein set forth.

2.2.2 The Prime Lease is by this reference incorporated into and made a part
hereof, except that:

          (i) all references in the Prime Lease to "Lessor", "Lessee", "Lease"
     and "Leased Premises", respectively, shall be deemed to refer to Sublessor,
     Sublessee, this Sublease and the Premises subleased hereunder,
     respectively; except that all references in the following sections and/or
     provisions of the Prime Lease to "Lessor", "Lessee", "Lease", and "Leased
     Premises", respectively, shall be deemed to refer to "Prime Lessor",
     "Sublessee", this "Sublease" and the "Premises subleased hereunder",
     respectively [i.e., it is the intention of the parties that Prime Lessor
     shall retain all of its rights and obligations under such sections and/or
     provisions; that Sublessor shall not be entitled to exercise any of Prime
     Lessor's rights, nor shall be bound by any of Prime Lessor's obligations,
     under such sections and/or provisions; and that Sublessee shall be entitled
     to exercise all of Tenant's rights, and shall be bound by all of Tenant's
     obligations, under such sections and/or provisions]:

          (a)  All of Section 2 except for the first sentence (relating to
               appurtenant rights and Prime Lessor's reserved rights)
          (b)  Section 6 (Utilities and Other Services)
          (c)  The second and the second from the last sentence of Section 10
               (relating to Lessor's obligations to maintain HVAC systems, the
               Building and its structural and mechanical systems); EXCEPT THAT
               Sublessee shall have no obligation to make any payments to Lessor
               for maintenance of the HVAC System
          (d)  Section 13 (Subordination)
          (e)  Section 19 (Rules and Regulations)

          (ii) the following sections and/or provisions of the Prime Lease are
     expressly EXCLUDED from this Sublease (i.e., they shall NOT be deemed to be
     incorporated in this Sublease) either because they are inapplicable or
     because they are superseded by specific provisions hereof:

          (a)  The first sentence of Section 2 (Leased Premises) (relating to
               the description of the Leased Premises)
          (b)  Section 2A (Parking)
          (c)  Section 3.1 (Term)
          (d)  Section 3.2 (Condition of the Premises)
          (e)  Section 3.2.1 (Lessee's Improvement Work)
          (f)  Section 3A (Construction of Bridge Between Buildings 700 and
               1400)
          (g)  Section 4 (Rent)
          (h)  Section 4A (Rent Commencement)
          (i)  Section 5 through 5.4.5 (Rent Adjustments)

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          (j)  The first six lines of Section 9A, beginning with "LESSOR agrees
               to keep the Building..." and ending with "boilers and other
               machinery and equipment, and"
          (k)  Section 10, except to the extent included in Section 2.2.2(i)
               above
          (l)  Section 12 (Assignment-Subletting)
          (m)  Sections 17 through 17A (Fire, Casualty and Eminent Domain)
          (n)  Section 20 (Broker)
          (o)  Section 22 (Notice)
          (p)  Section 24 (Expansion Rights)
          (q)  Section 25 (Option to Extend)

2.2.3 This Sublease is and shall remain subject and subordinate in all respects
to the Prime Lease and to all renewals, modifications, consolidations,
replacements and extensions thereof. In the event of termination or cancellation
of the Prime Lease for any reason whatsoever with respect to all or any portion
of the Premises, this Sublease shall automatically terminate with respect to all
or such portion of the Premises.

2.2.4 Notwithstanding anything contained in this Sublease to the contrary,
Sublessor shall have no obligation during the term of this Sublease to provide
any services of any nature whatsoever to Sublessee or to, in or for the benefit
of the Premises or to expend any money for the preservation or repair of the
Premises, or to observe or perform any obligations of Sublessor under this
Sublease in any case where such services, expenditures or obligations are
required under the Prime Lease to be provided, performed or observed by Prime
Lessor for the benefit of Sublessor with respect to the Premises, and Sublessee
agrees to look solely and directly to Prime Lessor for the furnishing of any
such services, expenditure of any such sums, or observance or performance of any
such obligations to which, or the benefit of which, Sublessee may be entitled
under this Sublease. Sublessor shall, however, upon the request of Sublessee
from time to time (which may be oral), notify Prime Lessor of any default by
Prime Lessor under the Prime Lease with respect to the Premises and to use
reasonable efforts to cause Prime Lessor to provide such services, expenditures
or obligations. For purposes of this Sublease and during the term of this
Sublease, Sublessor's only obligations as lessee under the Prime Lease with
respect to the Premises shall be to make those payments of rent due to Prime
Lessor thereunder, and to make those payments due to the utility providers for
utility services (including HVAC, electricity, water and sewer) which are
separately metered and furnished to the Leased Premises, which payments
Sublessor hereby agrees to make in timely fashion, and to use reasonable efforts
to cause Prime Lessor to provide the aforesaid services, expenditures and
obligations. It is the intention of the parties that Sublessee comply with, and
Sublessee agrees to comply with, all of the Sublessor's obligations as lessee
under the Prime Lease (not excluded under Section 2.2.2 above and except for
Sublessor's obligations to pay rent and utility charges to Prime Lessor and
others) with respect to the Premises to the same extent and with the same force
and effect as if Sublessee were lessee thereunder and Sublessee hereby agrees to
so comply with all of Sublessor's such obligations under the Prime Lease with
respect to the Premises. Sublessee shall have no claim against Sublessor for any
default by the Prime Lessor under Prime Lease; if, however, Sublessor is
entitled to a rent abatement equitably allocable to the Premises as a result of
any default by Prime Lessor, Sublessee shall be entitled to receive its fair and
equitable share of such abatement. If Prime Lessor shall default under any of
its obligations under the Prime Lease with respect to the Premises, Sublessee
shall have the right, at Sublessee's expense, but in the name of Sublessor, to
make demand or prosecute any appropriate action or proceeding against Prime
Lessor for the enforcement of the obligations of Prime Lessor

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with respect to the Premises. Sublessor agrees that it will cooperate with
Sublessee in such actions and proceedings and will sign such demand, pleadings
and/or other papers as may be required or appropriate, to enable the Sublessee
to proceed in Sublessor's name to enforce the obligations of Prime Lessor; but
Sublessee will pay all costs and expenses in the prosecution of any action or
any proceeding so taken by Sublessee and agrees to defend and indemnify
Sublessor against all costs and liability arising therefrom.

2.2.5 Sublessee shall neither do, nor permit to do nor permit to be done,
anything that would increase Sublessor's obligations to Prime Lessor under the
Prime Lease (unless Sublessee shall indemnify Sublessor from such increased
obligation) or that would cause the Prime Lease to be terminated or forfeited.
Sublessor hereby agrees that it shall not amend or modify the Prime Lease in any
manner that affects the Premises subleased hereunder without Sublessee's prior
consent, which consent shall not be unreasonably withheld.

2.2.6 Sublessor shall promptly give Sublessee a copy of any notice of default,
termination or otherwise affecting the existence or validity of the Sublease or
relating to any casualty or taking, given by Sublessor or Prime Lessor to the
other.

2.2.7 Sublessor and Sublessee hereby acknowledge that portions of the Premises
have direct access to portions of the Leased Premises located in Buildings 650
and 700 by means of existing interior corridors and doors. In recognition of
Sublessor's reasonable business safety, security and confidentiality needs,
Sublessee agrees that, except for its limited restroom/lavatory access rights
described in Section 2.3 below, Sublessee shall have no right whatsoever to
enter or have access to or otherwise use any space in Buildings 650 and 700.

2.3  SUBLESSEE'S RIGHTS RE BUILDING 700 LAVATORY USE

     Sublessor and Sublessee hereby acknowledge that, based upon Sublessee's
anticipated use of the Premises, the number of restroom/lavatory facilities
located in the Premises may be inadequate to meet Sublessee's expected need for
restroom/lavatory facilities. Accordingly to enable Sublessee to avoid the cost
of installing in the Premises the additional restroom/lavatory facilities that
might otherwise be required as a practical matter for Sublessee's expected need,
Sublessor hereby grants to Sublessee, subject to the conditions described below,
the right (the "Bldg 700 Lavatory Rights"), in common with Sublessor, to have
access through the fifth floor of Buildings 650 and 700 for the limited purpose
of traveling to and from, and use of, the restroom/lavatory facilities located
on the fifth floor of Building 700 and labeled "Fifth Floor Lavatories" on the
Attached Exhibit A; Sublessor also hereby grants to Sublessee the right to have
access through the fifth floor of Buildings 650 and 700 for the additional
limited purposes of having access to emergency exits during emergency
situations. Sublessee's Bldg 700 Lavatory Rights shall be in all events subject
to the following conditions:

     (a) The Bldg 700 Lavatory Rights may only be exercised during regular
business hours; as of the date of this Sublease, regular business hours are 8AM
to 6PM Mondays through Fridays, and 8AM to 1PM on Saturdays, but excluding
holidays. Neither Sublessee nor any Permitted User (as defined below) nor any
other person claiming by, through or under Sublessee shall have any right
whatsoever to exercise the Bldg 700 Lavatory Rights at any time outside regular
business hours.

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     (b) The Bldg 700 Lavatory Rights may only be exercised by (x) "Authorized
Personnel" (as defined below) and (y) visitors, customers, contractors and other
invitees of Sublessee who are accompanied by Authorized Personnel (Authorized
Personnel and such other persons are referred to herein collectively as
"Permitted Users").

     (c) In exercising the Bldg 700 Lavatory Rights, Permitted Users shall be
authorized to enter and exit Building 700 only through the one door labelled
"Access Door" on the attached Exhibit A, and once inside Building 700, Permitted
Users shall be authorized to travel between the Access Door and the Fifth Floor
Lavatories only through the portions of the corridor labelled "Access Corridor"
on Exhibit A. Neither Sublessee nor any Permitted User nor any person claiming
by, through or under Sublessee shall have any right whatsoever to enter or
travel through any portion of Buildings 650 and 700 other than the Access Door,
the Access Corridor and the Fifth Floor Lavatories.

     (d) For purposes of this Sublease, "Authorized Personnel" shall mean those
individual directors, officers and employees of Sublessee who have (x) received
written instructions approved by Sublessor that describe the times when, and the
terms and conditions under which, the Bldg 700 Lavatory Rights may be exercised;
(y) signed and delivered to Sublessor's Director of Security (or his designee) a
confidentiality agreement in form and substance satisfactory to Sublessor; and
(z) received from Sublessor's Director of Security (or his designee) a security
card which shall enable such person to have access through the Security Doors.

     If Sublessee, any Permitted User or any other person claiming by, through
or under Sublessee shall fail to observe and/or perform any of the terms,
provisions, conditions, restrictions, or agreements set forth in this Section
2.3 (including without limitation any failure to observe and/or perform any of
the terms, provisions, conditions, restrictions or agreements contained in the
confidentiality agreement described above), and such failure continues for five
(5) days after Sublessee's written notice of such failure from Sublessor, then
Sublessor shall have the right at any time thereafter to terminate and revoke
the Building 700 Lavatory Rights. In such case, the Sublessee shall, at its sole
expense, be solely responsible for undertaking whatever steps are necessary to
provide within the Premises the minimum number of restroom/lavatories required
for Sublessee's needs in the Premises.

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                                   ARTICLE III

                                TERM OF SUBLEASE
                                ----------------

3.1  TERM

     The Sublease Term of this Sublease shall be for the period specified in
Section 1.1 as the Sublease Term, unless earlier terminated or extended as
provided below.

                                   ARTICLE IV

                              CONDITION OF PREMISES
                              ---------------------

4.1  CONDITION OF PREMISES

     (a) Sublessee agrees to accept the Premises "as is", generally in the same
order and condition as the Premises are in as of the date hereof, and agrees
that Sublessor is under no obligation to perform any work upon or alteration to
the Premises for Sublessee's use and occupancy, other than to deliver the
Premises to Sublessee on the Commencement Date.

     (b) Sublessor will permit Sublessee and its agents to enter the Premises
prior to the Commencement Date in order to perform through Sublessee's own
contractors (to be first approved by Sublessor) any work necessary to prepare
the Premises for Sublessee's occupancy; all such work shall be performed
substantially in accordance with plans approved by Sublessor and Prime Lessor.
The foregoing license to enter prior to the Commencement Date is conditioned
upon Sublessee's workmen and mechanics working in harmony and not interfering
with the labor employed by Sublessor, Sublessor's mechanics or contractors or by
Prime Lessor or any other tenant or their contractors. If at any time such entry
shall cause disharmony or interference, this license may be immediately
withdrawn by Sublessor.

     Worker's compensation and public liability and property damage insurance,
all in amounts and with companies and on forms satisfactory to Sublessor, shall
be provided and at all times maintained by Sublessee or Sublessee's contractors
engaged in the performance of any work and, before proceeding with any work,
certificates of such insurance shall be furnished to Sublessor.

     Any such entry shall be deemed to be under all of the terms, covenants,
provisions and conditions of the Sublease except the covenant to pay Rent.

4.2  FIXTURES AND EQUIPMENT

     Sublessee shall be entitled to use all built-in fixtures and equipment,
including fume hoods physically located in the Premises as of the Commencement
Date. Sublessee shall, at its expense, maintain and repair such fixtures and
equipment in good order, repair and condition and shall surrender all such
fixtures and equipment to Sublessor in such condition at the end of the term,
reasonable wear and tear and damage by fire or other casualty excepted.

                                    ARTICLE V

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                         USE, ASSIGNMENT AND SUBLETTING
                         ------------------------------

5.1  PERMITTED USE; ACCESS

     Sublessee agrees that the Premises shall be used and occupied for the
Permitted Uses only. During the Sublease Term, Sublessee shall assume and
maintain exclusive control of the Premises. Sublessee acknowledges and
understands that it shall be responsible, at its expense, for providing any
janitorial, cleaning, equipment and fixture maintenance and security services
necessary for Sublessee's use and occupancy of the Premises. Sublessee shall
have access to the Premises and the appurtenant common areas of the Building 24
hours per day, seven days per week, subject to such "after hours" security
systems, rules and regulations as Prime Lessor may from time to time impose.

5.2  ASSIGNMENT AND SUBLETTING

     Sublessee shall not, without the prior written consent of both Sublessor
(which consent shall not be unreasonably withheld or delayed) and Prime Lessor
by operation of law or otherwise, assign, mortgage, pledge, encumber or in any
manner transfer this Sublease, or any part thereof or any interest of Sublessee
hereunder or sublet or permit the Premises or any part thereof to be used or
occupied by others. Notwithstanding any such consent, Sublessee shall remain
liable to Sublessor for the payment of all rent and for the performance of the
covenants and conditions of this Sublease (which liability, following any
assignment, shall be joint and several with the assignee).

                                   ARTICLE VI

                               RENT AND UTILITIES
                               ------------------

6.1  RENT

     (a) The Rent (specified in Section 1.1 hereof) and any additional rent or
other charges payable pursuant to this Lease shall be payable by Sublessee to
Sublessor by mailing such rent payment to Genzyme Corporation, P.O. Box 3486,
Boston, Massachusetts 02241-3486 (or such other place as Sublessor may from time
to time designate by notice to Sublessee).

     (b) Rent shall be payable in advance on the first (1st) day of each and
every calendar month during the term of this Sublease.

     (c) Rent for any partial month shall be paid by Sublessee to Sublessor at
such rate on a prorata basis. Other charges payable by Sublessee on a monthly
basis, as hereinafter provided, shall likewise be prorated.

     (d) All Rent and other amounts due under this Sublease shall be made
without demand, offset or deduction. Sublessee shall be entitled to a fair and
equitable share of all abatements of rent and rent adjustments set forth in the
Prime Lease which Sublessor has been granted with respect to the Premises.

     (e) Sublessee represents and Sublessor acknowledges that, as of the
Commencement Date and for the period of approximately six months thereafter,
Sublessee expects to use the

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approximately 2,638 rentable square foot portion of the Premises identified on
Exhibit A as the "Expansion Space" for only limited purposes. Accordingly,
Sublessor hereby agrees that Sublessee shall have no obligation to pay any rent
with respect to the Expansion Space until May 1, 1997. From and after May 1,
1997, however, full rent shall be due and payable with respect to the Expansion
Space. Sublessor shall provide Sublessee with such "free rent" for the Expansion
Space by applying to Sublessee's rental account for each month that Sublessee
qualifies for free rent, a credit in the amount of $8,353.67.

     (f) It is the intention of the parties that Rent payable by Sublessee under
this Sublease shall be a "gross rent" that includes amounts on account of base
rent, utilities, operating expenses and real estate taxes payable by Sublessee
to Sublessor; i.e.; except under the limited circumstances set forth in Section
6.3 below and except for Sublessee's obligations under Section 9.3 to pay for
parking spaces, Sublessee shall have no obligation to make any payments to
Sublessor other than the Rent specified in Section 1.1.

6.2  LATE PAYMENTS; ADDITIONAL RENT

     If any installment of Rent, additional rent or other charges is not paid
within five (5) business days of the date such payment is due and payable, then
Sublessee shall pay to Sublessor a late charge of five percent (5%) of the
amount of such payment. In addition, if Sublessee shall fail to make any such
payment within thirty (30) days after the due date, such payment shall bear
interest at the rate per annum which is two percent (2%) higher than the "prime
rate" then being charged by The First National Bank of Boston from the date such
payment became due to the date of payment thereof by Sublessee; provided,
however, that nothing contained herein shall be construed as permitting
Sublessor to charge or receive interest in excess of the maximum legal rate then
allowed by law. Such late charge and interest shall constitute additional rent
due and payable hereunder with the next installment of Base Rent due hereunder.

6.3  EXCESS UTILITY COSTS

     If Sublessor, in its reasonable judgment, determines that Sublessee is
using excessive quantities of HVAC, electricity or water (for purposes of this
Sublease, "excessive quantities" shall mean quantities more than 10% higher than
the quantities being consumed by Sublessor [calculated on a per square foot
basis] in portion of the Leased Premises used by Sublessor for purposes
comparable to Sublessee's use of the Premises), Sublessee shall, upon receipt of
a written invoice therefor, reimburse Sublessor for the cost of any such excess.

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                                   ARTICLE VII

                                    CASUALTY
                                    --------

7.1  CASUALTY AND RESTORATION

     If the Premises, or any part thereof, shall be damaged or destroyed by fire
or other casualty then Sublessee shall promptly notify Prime Lessor and
Sublessor. Under the Prime Lease the Prime Lessor is obligated, as soon as
possible thereafter, to repair or restore the Premises to the extent and in the
manner set forth in Section 17 of the Prime Lease. If damage is of the type
which entitles Prime Lessor or Sublessor to terminate the Prime Lease and either
such party so elects to terminate the Prime Lease, then the Prime Lease shall
cease and come to an end and this Sublease shall similarly terminate. In
addition, if damage is of the type which would entitle Sublessor to terminate
the Prime Lease, Sublessee shall have the right to terminate this Sublease by
giving both Sublessor and the Prime Lessor written notice of such termination
within the applicable notice period set forth in Section 17 of the Prime Lease.
Sublessee acknowledges that Sublessor shall, in no event, have any obligation
whatsoever to rebuild or restore any damage to the Premises.

     If during the Sublease Term the Building shall be partially or
substantially damaged by fire or casualty and if such partial or substantial
damage shall materially interfere with the Sublessee's use of the Premises as
contemplated by this Sublease, a just amount of the rent and other charges
payable by the Sublessee hereunder shall be equitably abated or adjusted for the
period in which, by reason of such damage, there is such interference with the
use of the Premises, but only to the extent that Sublessor is also entitled to
an abatement under the Prime Lease on account of such fire or casualty that is
equitably allocable to the Premises subleased hereunder.

                                  ARTICLE VIII

                                 EMINENT DOMAIN
                                 --------------

8.1  EMINENT DOMAIN

     Should the Building or any part thereof be taken by eminent domain and such
taking (or damage caused by such taking) is of the type which entitles Prime
Lessor or Sublessor to terminate the Prime Lease and either such party elects to
terminate the Prime Lease, then, and in that event, the Prime Lease shall cease
and come to an end and this Sublease shall cease and come to an end, and the
Rent shall be apportioned as of the date of the termination notice.

     If any such taking renders the remaining portion of the Premises unsuitable
for the purposes of Sublessee (in Sublessee's reasonable judgment), then
Sublessee shall have the right to terminate this Sublease by written notice to
Sublessor which shall be within sixty (60) days of the public recording of such
taking. In the event of termination by Sublessee as set forth above, the Rent
shall be apportioned as of the date of such termination notice. In addition, if
any taking is of the type which would entitle Sublessor to terminate the Prime
Lease, Sublessee shall have the right to terminate this Sublease by giving both
Sublessor and the Prime Lessor written notice of such termination within the
applicable notice period set forth in Section 17A of the Prime Lease.

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     In the event of a taking described in Section 17A of the Prime Lease, the
rent and other charges payable hereunder, or a fair and just proportion thereof
according to the nature and extent of the loss of use, shall be suspended or
abated, but only to the extent that Sublessor is also entitled to an abatement
or suspension under the Prime Lease on account of such taking that is equitably
allocable to the Premises subleased hereunder.

     Sublessor reserves, and Sublessee grants to Sublessor all rights which the
Sublessee may have for damages or injury to the Premises for any taking by
eminent domain, except for damage to the Sublessee's fixtures, personal property
or equipment, if any, the Sublessee's right to relocation expenses, if any, and
the Sublessee's right for business interruption, if any.

                                   ARTICLE IX

                            MISCELLANEOUS PROVISIONS
                            ------------------------

9.1  NO BROKERAGE

     The parties represent that they have dealt with no real estate broker or
agent in connection with this Sublease other than Robert Richards of Fallon
Hines & O'Connor, and in the event of any brokerage claims against Sublessor
from any broker other than Fallon, Hines & O'Connor, predicated upon prior
dealings with Sublessee, Sublessee hereby agrees to defend, indemnify and hold
harmless Sublessor from and against any such claim.

9.2  NOTICES

     Whenever by the terms of this Sublease notice, demand or other
communication shall or may be given, either to Sublessor or to Sublessee, the
same shall be adequately given if in writing and delivered by hand or sent by
registered or certified mail, postage prepaid:

     If intended for Sublessor, addressed to it at the mailing address set forth
     on the first page of this Lease, with a copy to Sublessor's attorneys,
     Palmer & Dodge LLP, One Beacon Street, Boston, Massachusetts 02108,
     Attention: Maureen P. Manning, Esquire and Thomas G. Schnorr, Esquire (or
     to such other address or addresses as may from time to time hereafter be
     designated by Sublessor by like notice).

     If intended for Sublessee, addressed to it at the Premises to the attention
     of the Director of Finance (or to such other address or addresses as may
     from time to time hereafter be designated by Sublessee by like notice).

All such notices shall be effective upon receipt or refusal to receive.

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9.3  PARKING

     Under the terms of the March 8, 1996, Third Amendment to the Prime Lease,
Sublessor is entitled, as a right appurtenant to the Leased Premises, to use a
certain number of parking spaces in the One Kendall Square Parking Garage upon
payment of the then current monthly parking fee determined in accordance with
the last paragraph of Section 4 of the Prime Lease. Sublessor shall make
available to Sublessee during the term of this Sublease, at Sublessee's expense,
the right to use up to 16 of such parking spaces in such garage.

9.4  PRIME LESSOR CONSENT

     This Sublease shall not be effective until and unless Prime Lessor has
given its consent hereto. Sublessor shall not be responsible for the failure of
Prime Lessor to consent to this Sublease.

     EXECUTED UNDER SEAL.

                   Sublessor:                 GENZYME CORPORATION
                                              By  /S/ EVAN M. LEBSON
                                              --------------------------------
                                              Its Vice President and Treasurer
                                              hereunto duly authorized

                   Sublessee:                 DYAX CORP.

                                              By  /S/ HENRY E. BLAIR
                                              ---------------------------------
                                              Its Chairman
                                              hereunto duly authorized

                                     - 12 -
<PAGE>

                              [GENZYME LETTERHEAD]

                                January 23, 1998

Dyax Corp.
One Kendall Square, Bldg. 600
Cambridge, MA 02139
Attention: Director of Finance

         Re:   Sublease dated as of September 21, 1996, between Genzyme
               Corporation, as Sublessor, and Dyax Corp., as Sublessee, with
               respect to premises consisted of approximately 16,183 square
               feet located on the Fifth Floor of Building 600 at One Kendall
               Square, Cambridge, Massachusetts

Gentlemen:

     The purpose of this letter is to confirm the agreement that we reached on
December 31, 1997 to extend the term of the captioned Sublease as of December
31, 1997 as follows:

     1.   The expiration date of the Sublease is hereby extended from September
          30, 1998, through and including December 31, 1999 (such extension
          period is referred to as the "Extended Term").

     2.   Sublessee has no rights or options to extend the term of the Sublease
          beyond such expiration date.

     3.   Except as amended hereby, the Sublease remains unchanged and in full
          force and effect.

     Please acknowledge your agreement to the foregoing by having the two
enclosed copies of this letter signed by an authorized officer of Dyax Corp.
Once this letter is so

                     [This space intentionally left blank.]
<PAGE>

Dyax Corporation
January 23, 1998
Page 2

signed and returned to me and approved by Prime Lessor, this letter shall
constitute an amendment to the Sublease.

                                                  Very truly yours,

                                                  GENZYME CORPORATION

                                                  By: /s/ Peter Wirth
                                                      --------------------------
                                                      Peter Wirth
                                                      Executive Vice President
                                                      Chief Legal Officer

Enclosures (2)
cc:  Thomas G. Schnorr, Esquire

Accepted and Agreed to this 23rd day of January, 1998:

DYAX CORP.

By: /s/ Henry E. Blair
    --------------------------------
    Its President
    Hereunto duly authorized

The undersigned, as successor to the Trustees of Old Kendall Realty Trust as
Prime Lessor, hereby consents to the foregoing:

OLD KENDALL PROPERTY LLC

By: /s/ Allan R. Jones, President, Managing Member
   --------------------
Dated: January 26, 1998<PAGE>

                                                                Exhibit 10.17

                          SECOND AMENDMENT TO SUBLEASE

      This Second Amendment to Sublease (the "Second Amendment") is entered into
as of March 21, 2000 by and between Genzyme Corporation, a Massachusetts
corporation (the "Sublessor") and Dyax Corp., a Delaware corporation (the
"Sublessee"). The effective date of this Second Amendment is January 1, 2000.
Capitalized terms used herein and not otherwise defined shall have the meaning
given to them in the Sublease (as defined below).

      WHEREAS, a Sublessor and Sublessee entered into a Sublease dated September
21, 1996 (the "Sublease") with respect to premises consisted of approximately
16,183 square feet located in the Fifth Floor of Building 600 at One Kendall
Square, Cambridge, Massachusetts;

      WHEREAS, Sublessor and Sublessee amended the Sublease pursuant to a Letter
Agreement dated as of January 23, 1998 with an effective date of December 31,
1997; and

      WHEREAS, Sublessor and Sublessee wish to further amend certain provisions
of the Sublease, as amended.

      NOW THEREFORE, in consideration for the foregoing premises and the
following covenants and promises, the parties agree and acknowledge as follows:

      1. The expiration date of the Sublease is hereby extended from December
31, 1999, through and including June 30, 2001 (such extension period is referred
to as the "Extended Term").

      2. Sublessee shall have the option to extend the Extended Term for six (6)
additional one month periods commencing on July 1, 2001 (each such additional
one month period is referred to as an "Option Term"). Not less than ten (10)
days prior to the expiration of the Extended Term or any Option Term, Sublessee
shall provide Sublessor with written notice of its intention to either (i)
terminate the Sublease at the end of the Extended Term or the Option Term, or
(ii) continue the Sublease for the next Option Term. In no event shall Sublessee
have the right to extend the Term of the Sublease beyond December 31, 2001.

      3. The Rent payable by the Sublessee to Sublessor for the Premises shall
be $647,320 per annum ($40.00 per square foot or $53,943.33 per month).

      4. Except as specifically amended hereby, the Sublease remains unchanged
and in full force and effect.

      5. This Second Amendment shall not be effective until and unless Prime
Lessor has given its consent hereto. Sublessor shall not be responsible for the
failure of Prime Lessor to consent to this Second Amendment.
<PAGE>

      IN WITNESS WHEREOF, this Second Amendment has been executed as of the date
first set forth above.

                                          Sublessor:

                                          GENZYME CORPORATION

                                          By: /s/ Frank Ollington
                                             -------------------------------
                                          Name:
                                          Title:

                                          Subtenant:

                                          DYAX CORP.

                                          By: /s/ Henry E. Blair
                                              ------------------------------
                                          Name:
                                          Title:

                                       2

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