Document:

<Page>

                                                                   EXHIBIT 10.18

                                      LEASE

1.   IDENTIFICATIONS

     This LEASE made as of the 29th of May, 1997, by and between William
J. Callahan, (the "Landlord"), having an address c/o P.O. Box 269 Bedford, MA
01730 and NitroMed, Inc., (the "Tenant"), a Delaware Corporation having an
address at 801 Albany Street, Boston, MA 02118.

2.   LEASE: THE PREMISES

     In consideration of the Basic Rent, Additional Rent and other payments and
covenants of the Tenant hereinafter set forth, and upon the following terms and
conditions, the Landlord hereby leases to the Tenant and the Tenant hereby
leases from the Landlord that certain parcel of land containing 3.665 +/- acres
of land shown as Lot 16 on Exhibit A attached hereto (the "Property"), known as
12 Oak Park Drive in Bedford, MA together with the two-story building of
approximately 40,000 gross square feet of space and all parking facilities
located thereon (the "Building", and together with the Property the "Premises").
The Landlord, at his own cost and expense, reserves the rights, subject to prior
consent of Tenant which shall not be unreasonably withheld or delayed, to
relocate and to install, maintain, repair, replace and grant easements for
utility lines, pipes and conduits across the Property for the benefit of other
properties, all without any material interference with or any material
interruption of the use and enjoyment of or access to the Premises by the Tenant
as contemplated hereby.

3.   INITIAL CONSTRUCTION BY TENANT

     Landlord shall deliver occupancy of the Premises with building systems and
roof in good operating order and, as to the roof, watertight and otherwise in
"as is" condition. All work necessary to prepare the Premises for occupancy by
Tenant shall be performed by Tenant, at its own expense, and Landlord shall have
no responsibility therefor. Plans and specifications for all

<Page>

such work shall be submitted to Landlord and are subject to approval by Landlord
prior to commencement of any such work, which approval shall not be unreasonably
withheld or delayed. In the event of disapproval, Landlord shall give written
notice of the same to Tenant which shall specify all of Landlord's objections
and Tenant shall, as soon as possible thereafter, submit new plans and
specifications for approval corrected so as to satisfy all such objections,
provided, however, that Landlord shall be deemed to have approved any plans and
specifications submitted by Tenant if Landlord does not give notice of its
objections thereto within ten (10) days following receipt of such plans and
specifications. Landlord shall not be a party to nor incur any liability as a
result of any contract to perform any of Tenant's work. Tenant's work shall be
done by contractors, subcontractors and other laborers previously approved by
Landlord, which approval shall not be unreasonably withheld or delayed. Tenant
shall not commence utilization of the Premises for the permitted Use unless and
until it shall have delivered to Landlord, a certificate of use and occupancy
from the local building department duly authorizing such utilization pursuant to
the Massachusetts State Building Code. If Tenant undertakes any such work in the
Premises (being under no obligation to do so), Tenant shall proceed with such
work, deliver such certificate and commence utilization of the Premises for the
permitted Use with commercially reasonably diligence.

     3.1     ENTRY BY TENANT PRIOR TO TERM COMMENCEMENT DATE

     Tenant may enter the Demised Premises prior to the Term Commencement Date
to undertake such work as is to be performed by Tenant pursuant to this Lease in
order to prepare the Premises for Tenant's occupancy. Such entry shall be deemed
to be pursuant to a license from Landlord to Tenant and shall be at the risk of
Tenant.

                                        2
<Page>

4.   TERM

     The Term of this Lease shall commence on May 29, 1997 (the "Term
Commencement Date") and shall expire, unless earlier terminated in accordance
with the terms hereof, at midnight on the last day of May 31, 2004.

5.   USE OF THE PREMISES: LICENSES AND PERMITS

     The Tenant shall use the Premises only for offices, testing laboratory,
research laboratory or any other lawful use, to the extent from now and
hereafter time to time permitted under applicable laws, by-laws ordinances,
codes, rules, regulations, orders and other lawful requirements of governmental
bodies having jurisdiction. The Tenant, its subtenants, licensees, invitees and
any other users of the Premises shall apply in their own names for and obtain at
their own expense any and all licenses, permits and other approvals which may be
required from such governmental bodies in connection with any particular use of
the Premises during the Term.

6.   BASIC RENT: ADDITIONAL RENT

     During the Term, the Tenant shall pay Basic Rent to the Landlord at a rate
equal to five hundred eighty thousand dollars, $580,000 per year, except
modified as follows: May 1997 - No Base Rent; June 1997 - $40,000; July 1997 -
$40,000; August 1997 - $40,000; September - $40,000.

     Basic Rent shall be payable in advance on the first day of each month in
equal installments (except in the case of a partial month at the beginning of
the Term, in which event the Tenant shall pay the appropriate pro rata
proportion of such installment) to the Landlord at the address set forth above
or such other address as the Landlord may thereafter specify by notice to the
Tenant, without counterclaim, set off, deduction or defense and except as
otherwise expressly provided herein, without abatement.

                                        3
<Page>

     Basic Rent shall be net of all costs and expenses related to the Premises
except as expressly otherwise provided herein. The Tenant agrees to pay to the
Landlord upon demand as Additional Rent, in the same manner as Basic Rent, any
and all charges, costs, expenses, and obligations (except for those items which
are Landlord's obligation under this Lease) as the Landlord may from time to
time actually incur in good faith with regard to the maintenance of the
Premises, in accordance with the terms and provisions of this Lease. The
Landlord shall, in each case, at the time of demand for payment, provide the
Tenant with evidence of payment of or liability for such other charges, costs,
expenses and obligations.

7.   TAXES

     The Tenant shall pay or cause to be paid to the Landlord (or, where
appropriate, directly to the authority by which the same are assessed or
imposed, with evidence of such payment to the Landlord) as Additional Rent not
later than ten (10) days prior to the date the same are due or twenty-one (21)
days after written notice and delivery of a copy of the actual tax bill thereof
to the Tenant, whichever is later, all taxes and excises upon the personal
property and equipment of the Tenant located at the Premises or the Property and
all real estate taxes, betterments and special assessments (which the Landlord
agrees shall be paid over the longest period allowed by law) or amounts in lieu
or in the nature thereof and any water rents or sewer use charges (and the
entire amount of any interest, penalties and costs attributable to delayed
payment thereof where such delay is the fault of the Tenant) which may now or
hereafter be levied, assessed or imposed by the United States of America, The
Commonwealth of Massachusetts, the Town of Bedford or any other authority, or
become a lien, upon all or any part of the Property, the Building, the Premises,
the use or occupation thereof, or upon the Landlord and the Tenant in respect
thereof, or upon the basis of rentals thereof or therefrom (except for the
Landlord's income, estate, gift or

                                        4
<Page>

transfer taxes), or upon the estate hereby created or upon the Landlord by
reason of ownership of the reversion, provided that Tenant shall only be liable
for the foregoing to the extent the same accrue during the term of this lease.
All payments by the Tenant on account of Taxes shall be applied prorata in
connection with any tax bills received by Landlord covering periods which are
not within the Term. Landlord shall provide Tenant with a municipal lien
certificate which confirms that real estate taxes are current by April 11, 1997.

     The Tenant shall, upon written notice from the Landlord that the same is
required by any Mortgagee (as defined in Paragraph 21 hereof), prepay to the
Mortgagee monthly as Additional Rent, in the same manner as Basic Rent,
one-twelfth (1/12) of the total of all such amounts as the Landlord may from
time to time reasonably estimate will be payable annually by the Tenant under
this Paragraph 7, which prepayments the Landlord agrees shall be applied,
without interest to such amounts as actually become payable. As soon as any such
amounts so payable are actually determined, appropriate adjustment of any
overpayments and underpayments shall be made.

     The Tenant shall have the right in its own name or in the name of the
Landlord to contest or review by legal proceedings or otherwise any such tax,
levy, charge or assessment. In such event the Tenant shall either pay such tax,
levy, charges or assessment (under protest, if necessary) or shall, if
requested, deposit with the Landlord in trust an amount sufficient to cover the
contested item together with any interest, penalties or costs as the Landlord
may reasonably require. The Tenant shall defend, indemnify and save the Landlord
harmless from and against and shall pay as Additional Rent (i) any such tax,
levy, charge or assessment that may be determined to be due and (ii) any and all
costs or expenses the Landlord may incur in connection with any such
proceedings. When any such contested item shall have been settled or paid, the

                                        5
<Page>

balance of any sums deposited with the Landlord in trust shall be repaid to the
Tenant. The Tenant shall be entitled to share in any refund or abatement, net of
such costs and expenses, which may be made of any tax, levy, charge or
assessment in the same proportion that the same was paid by the Tenant or with
the Tenant's funds.

8.   INSURANCE: WAIVERS OF SUBROGATION

     The Tenant shall, at its own cost and expense, obtain and throughout the
Term shall maintain, insurance from companies qualified to do business in
Massachusetts and reasonably acceptable to the Landlord, for the benefit as
additional insureds of the Landlord and any Mortgagees, the existence of which
Tenant has received written notice from Landlord as their respective interests
may appear, as follows:

     (i) comprehensive general liability insurance against claims for bodily
injury, death or -property damage occurring to, or on the Premises, in limits of
$1,000,000 for bodily injury or death and $500,000 for property damage or in
such higher or lower limits as may result from the operation of clause (iv)
below:

     (ii) boiler and machinery insurance on any steam boilers, pressure vessels
and pressure piping, rotating electrical machines, and miscellaneous electrical
apparatus, engines, pumps, and compressors, fans and blowers, with so-called
"standard blanket coverage" (15 HP and over) to a limit of $1,000,000;

     (iii) insurance against lost rentals for a period of one year and against
loss or damage to the improvements, and any other buildings, structures and
improvements from time to time constituting a part of the Premises, such as may
result from fire and such other casualties as are normally covered by an
"extended coverage" endorsement, in an amount equal to the greater of

                                        6
<Page>

(a) the replacement costs of the improvements constituting part of the Premises,
or (b) an amount sufficient to preclude any claim on the part of the insurer for
co-insurance under the terms of applicable policies. The term "replacement
costs" shall mean the actual costs of restoration (excluding foundation and
excavation costs) as nearly as practicable to a condition functionally
equivalent and of equal value as immediately prior to the casualty, and shall be
redetermined by such insurer every two years and

     (iv) at the written request of the Landlord, such other commercially
customary insurance coverages and such additional commercially customary
coverage amounts as any Mortgagee may reasonably require and as a prudent and
reasonable owner would from time to time carry on similar premises in view of
any new risks arising or changes of conditions (e.g., inflation) occurring
during the Term.

     At the commencement of the Term and thereafter not less than ten (10) days
prior to the expiration dates of the policies theretofore in effect,
certificates of the foregoing required insurance policies, issued by the
insurers, shall be delivered to the Landlord.

     Neither the Landlord nor the Tenant shall be liable to the other for any
loss or damage to the Premises or other property or injury to or death of
persons occurring on the Premises or in any manner growing out of or connected
with the Tenant's use and occupation of the Premises or the condition thereof,
whether or not caused by the negligence or other fault of the Landlord, the
Tenant or their respective agents, employees, subtenants, licensees, invitees or
assignees; provided, however, that this release (i) shall apply only to the
extent that such loss or damage to the Premises or other property or injury to
or death of persons is covered by insurance which protects the Landlord, or the
Tenant or both of them as the case may be; (ii) shall not be construed to impose
any other or greater liability upon either the Landlord or the Tenant than

                                        7
<Page>

would have existed in the absence hereof; and (iii) shall be in effect only so
long as the applicable insurance policy contains a clause to the effect that
this release shall not affect the right of the insureds to recover under such
policies, which clauses shall be obtained by the parties hereto whenever
available at reasonable expense.

9.   UTILITIES

     The Tenant shall, at its own cost and expense, arrange and pay for all
services and utilities provided to the Premises during the Term, including
without limitation, water, electricity, fuel, steam, heat, air conditioning,
sewer service, telephone service, security and fire protection, cleaning and
trash removal, and snow and ice removal.

10.  REPAIRS

     Notwithstanding anything to the contrary herein, from and after the
commencement of the Term, the Landlord shall, at its own cost and expense, make
all repairs necessary to keep the structural support elements (which term shall
include the footings and foundations, floor slab, exterior walls, structural
columns, planking beams and girders of the Building) in structurally good
condition, order and repair, excepting any damage resulting from any acts and
any omissions of the Tenant or its agents, contractors and employees. The party
from time to time having the responsibility for repair of any portion of the
Premises shall have (and, to the extent necessary to effectuate this paragraph
the Landlord hereby assigns to the Tenant) the benefit of all warranties and
guarantees from manufacturers, suppliers and subcontractors whose products or
services are or may be incorporated into the Premises.

     Subject to the terms and provisions of the immediately following paragraph,
the Tenant shall, at its own cost and expense, make all other repairs,
structural and non-structural, exterior and interior, necessary to keep the
Premises, including the sidewalks, curbs, and driveways

                                        8
<Page>

adjoining the Premises and all electrical, mechanical, sprinklers, plumbing,
heating, air conditioning and other building systems serving the Premises in as
good condition, order and repair as the same are at the commencement of the Term
or thereafter may be put, excepting only repairs which are the obligation of the
Landlord hereunder and damage resulting from any acts and omissions of the
Landlord or its agents, contractors and employees, from reasonable wear and use
and from fire or other casualty and eminent domain takings, and shall keep and
maintain all portions of the Premises and the sidewalks and driveways adjoining
the same in a clean and orderly condition, free of accumulation of dirt,
rubbish, snow and ice.

11.  COMPLIANCE WITH LAWS AND REGULATIONS

     The Tenant agrees that its obligations to make payment of the Basic Rent,
Additional Rent and all other charges on its part to be paid, and to perform all
of the covenants and agreements on its part to be performed during the Term
hereunder shall not be affected by any present or future law, by-law, ordinance,
code, rule, regulation, order or other lawful requirement regulating or
affecting the use which may be made of the Premises or the Property.

     During the Term the Tenant shall comply, at its own cost and expense, with:
all applicable laws, by-laws, ordinances, codes, rules, regulations, orders and
other lawful requirements of the governmental bodies having jurisdiction whether
or not foreseeable, and whether or not they involve any changes in governmental
policy, which are applicable to the Premises, the fixtures and equipment
therein, or the Tenant's particular use thereof; the order, rules and
regulations of the National Board of Fire Underwriters, or any other body
hereafter constituted exercising similar functions, which may be applicable to
the Premises, the fixtures and equipment therein or the use thereof; and the
requirements of all policies of public liability,

                                        9
<Page>

fire and all other types of insurance at any time in force with respect to the
Premises, the Building or the Property and the fixtures and equipment therein
and thereon.

12.  ALTERATIONS BY TENANT

     Tenant shall have the right to erect a building sign indicating the name
and logo of Tenant which is consistent with the size and quality of other
building signs within Oak Park. Tenant will obtain approval for any such sign
from Landlord, approval not to be unreasonably withheld or delayed.

     The Tenant shall make no alterations, additions or improvements in or to
the Premises without first submitting to the Landlord plans and specifications
therefore in such detail as the Landlord may reasonably require and obtaining
the Landlord's prior written consent. The Landlord agrees that its consent shall
not be unreasonably withheld or delayed for interior, nonstructural alterations,
additions and improvements consistent with the use of the Premises as
contemplated hereby; any such consent to interior, nonstructural alterations,
additions and improvements, if the Landlord so advises the Tenant at the time of
such consent, may be conditioned upon the Tenant's being obligated to remove the
same at the expiration or termination of this Lease and to restore the Premises
to their condition prior to such alterations, additions and improvements. Upon
completion of any such alterations, additions or improvements, Tenant shall
deliver "as built" plans to Landlord. The Tenant shall promptly pay when due the
entire cost of any work undertaken such that the Premises shall at all times be
free of mechanics and materialmen's liens or claims. All work undertaken by the
Tenant shall be accomplished in accordance with all applicable laws and in a
good workmanlike manner, using first class materials. Notwithstanding the
foregoing, Landlord's consent shall not be required for

                                       10
<Page>

nonstructural alterations which do not affect the base building HVAC,
electrical, and plumbing systems having a cost of up to $20,000.

13.  LANDLORD'S ACCESS

     The Tenant agrees to permit the Landlord and any Mortgagees and their
authorized representatives to enter the Premises at all reasonable times during
usual business hours after at least 24 hours prior oral notice and accompanied
by Tenant's representative for the purposes of inspecting the same, exercising
such other rights as it or they may have hereunder or under any mortgage and at
any time without notice in the event of emergency. In no event, however, shall
the exercise of such rights of access unreasonably interfere with Tenant's
business operations.

14.  INDEMNITIES

     The Tenant agrees to protect, defend (with counsel reasonably approved by
the Landlord), indemnify and save the Landlord harmless from and against any and
all claims (except structural defects which are not caused by Tenant) and other
than claims arising from any omission, fault, negligence or other misconduct of
the Landlord or its agents or employees in or on the Premises, the Building or
the Property) arising: (i) from the conduct or management of or from any work or
thing whatsoever done in or on the Premises during the Term; and from any
condition existing in the Premises, or any injury to or death of persons or
damage to property occurring during the Term, or resulting from an occurrence
during the Term, in or on the Premises, and (ii) at any time after the date
hereof, and without regard to the expiration or termination of the Term, from
any breach or default on the part of the Tenant in the performance of any
covenant or agreement on the part of the Tenant to be performed pursuant to the
terms of this Lease or from any negligent act or omission on the part of the
Tenant or any of its agents, employees, subtenants, licensees, invitees, or
assignees. The Tenant further agrees to indemnify

                                       11
<Page>

the Landlord from and against all costs, expenses, and other liabilities
incurred in connection with any such indemnified claim or action or proceeding
brought thereon, any and all of which, if reasonably suffered, paid or incurred
by the Landlord, the Tenant shall repay upon demand to the Landlord as
Additional Rent.

15.  CASUALTY DAMAGE

     Except as provided below, in the event of partial or total destruction of
the Premises and any other buildings, structures and improvements from time to
time constituting a part of the Premises during the Term by fire or other
casualty, the Landlord shall as promptly as practicable after receipt of any
insurance proceeds available as a result of such casualty, repair, reconstruct
or replace the portions of the Premises destroyed as nearly as possible to their
condition prior to such destruction, except that in no event shall the Landlord
be obligated to expend more for such repair, reconstruction or replacement than
the amounts of any such insurance proceeds actually received. During the period
of such repair, reconstruction and replacement there shall be an equitable
abatement of Basic Rent and Additional Rent hereunder in proportion to the
nature and extent of the destruction but only as and to the extend such
abatement is covered by lost rentals insurance for the benefit of the Landlord
as required by Paragraph 8 hereof or otherwise.

     If (i) the Premises and any other buildings, structures and improvements
from time to time constituting part of the Premises are so extensively destroyed
by fire or other casualty that the Premises and any other buildings, structures
and improvements from time to time constituting part of the Premises are not
susceptible of repair, reconstruction or replacement within nine (9) months from
the date work commences thereon, or (ii) if such destruction resulted from
causes or risks not required to be insured against by the Tenant hereunder, (or
any Mortgagee refuses to make such proceeds available) the Tenant may terminate
this Lease by

                                       12
<Page>

giving written notice to the Landlord within thirty (30) days after the date of
such destruction unless, as to a termination within (ii) of this paragraph
within thirty (30) days after such notice to the Landlord, the Landlord gives
notice to the Tenant that the Landlord will make the necessary additional funds
available for such repair, reconstruction or replacement. There shall be an
equitable abatement of Basic Rent and Additional Rent hereunder from the date of
the casualty but only as and to the extent such abatement is covered by lost
rentals insurance for the benefit of the Landlord as required by Paragraph 8
hereof. Further, in the event Landlord commences repair, reconstruction and
replacement in accordance with the terms of this Paragraph 15 but fails to
complete same within nine (9) months thereafter, Tenant shall have the right to
terminate this Lease immediately upon notice to Landlord and upon receipt of
such notice, the security deposit shall be returned to Tenant and neither party
shall have any further obligations.

16.  CONDEMNATION

     If all or substantially all of the Premises shall be taken or appropriated
by any public authority, or if more than twenty percent (20%) of the floor area
of the Building or of the parking areas shall be so taken or appropriated and
either the Landlord or the Tenant, within sixty (60) days after it first
receives notice of such taking, gives written notice to the other to such
effect, this Lease shall terminate as of the date the Tenant must surrender
possession or, if later, the date the Tenant actually surrenders possession, and
the Basic Rent and Additional Rent reserved shall be apportioned and paid to and
as of such date.

     The Landlord hereby reserves, and the Tenant hereby assigns to the
Landlord, any and all claims to the entirety of any damages or other
compensation by way of damages which may be awarded in connection with any such
taking or appropriation except for Tenant rights to recover by separate award,
Tenant improvements and relocation expenses.

                                       13
<Page>

     If any part of the Premises is taken or appropriated by public authority as
aforesaid and neither the Landlord nor the Tenant terminates this Lease as set
forth above, the Landlord shall promptly and diligently, secure and close so
much of the improvements and any other buildings, structures and other
improvements constituting a part of the Premises as remain and shall, to the
extent possible, replace any part so taken or appropriated by a suitable
structure or addition of similar size and design to the improvements so taken or
appropriated, except that in no event shall the Landlord be obligated to expend
more for such replacement than the amount of any damages, compensation or award
which the Landlord may actually receive as damages in respect of such
improvements as they existed immediately prior to such taking or appropriation;
in such event there shall be an equitable abatement of Basic Rent, in proportion
to the reduced fair rental value of the Premises, from and after the date the
Tenant must surrender possession or, if later, the date the Tenant actually
surrenders possession.

17.  LANDLORD'S COVENANT OF QUIET ENJOYMENT

     The Landlord covenants that the Tenant, upon paying the Basic Rent and
Additional Rent and performing and observing all of the other covenants and
provisions hereof, may peacefully and quietly hold and enjoy the Premises for
the Term as aforesaid, subject, however, to all of the terms and provisions of
this Lease.

18.  TENANT'S OBLIGATION TO QUIT

     The Tenant shall, upon expiration of the Term or other termination of this
Lease, leave and peaceably and quietly surrender and deliver to Landlord the
Premises and all improvements, building equipment and fixtures thereon and any
replacements or renewals thereof in as good condition, order and repair as the
same are required to be kept by the Tenant pursuant to Paragraph 10 hereof,
normal wear and tear, damage by fire or other casualty or taking by

                                       14
<Page>

eminent domain excepted, however, that the Tenant may first remove any trade
fixtures, equipment and other personal property of the Tenant and shall first
remove any other alterations, additions and improvements which the landlord has
required be removed pursuant to the terms of Paragraph 12 hereof or, at the
option of the Landlord, which were made without the consent (if required) of the
Landlord pursuant to the terms of Paragraph 12 hereof, restoring the Premises in
each case to as nearly as reasonably possible their condition prior to the
installation of such fixtures or the undertaking of such alternations, additions
or improvements, as the case may be, giving effect, however, to the overall
condition of the balance of the Premises as required at the time of such
restoration.

19.  TRANSFERS OF TENANT'S INTEREST

     The Tenant shall not assign or sublease or otherwise encumber all or any
part of its interest in this Lease, the Premises, or the estate hereby created,
nor shall it grant any licenses, concessions or the like, without in each case
first obtaining the proper written consent of the Landlord, which consent shall
not be unreasonably withheld or delayed.

     Notwithstanding the foregoing provided the Tenant delivers to the Landlord
prior written notice and a copy of the appropriate legal documentation and
financial information, no consent of Landlord shall be required for any
assignment of the Tenant's interest to any successor to the Tenant by reason of
any merger, consolidation or sale of all or a substantial portion of its stock
or assets or for any sublease or assignment of such interest to any entity
controlled by Tenant. In addition, no consent of Landlord shall be required for
any assignment of this Lease or subletting of all or any portion of the Premises
to any entity under common ownership or control as Tenant provided that such
entity, at the time of such assignment or subletting, has a net worth equal to
or greater than the net worth of Tenant as of the date hereof.

                                       15
<Page>

     Any attempted sublease or assignment without the required consent of the
Landlord shall be void. In all events the Tenant originally named herein shall
remain primarily liable for, and any sublessee or assignee shall in writing
assume, the obligations of the Tenant under this Lease, and the Landlord may
condition any required consent to any sublease or assignment upon the Tenant's
agreeing to pay to the Landlord fifty percent (50%) of the amount by which any
NET rentals and other amounts from time to time payable to or for the benefit of
the Tenant thereunder exceed the Basic Rent and Additional Rent from time to
time payable hereunder, after the payment of brokerage commissions, legal costs,
and tenant improvement expenses incurred in connection therewith. (And, in the
case of a sublease on a gross rent basis, net of that portion of the rent that
would constitute Additional Rent hereunder).

20.  TRANSFERS OF LANDLORD'S INTEREST

     The Landlord shall have the right from time to time to sell or mortgage its
interest in the Property, the Building and the Premises, to assign its interest
in this Lease, or to assign from time to time the whole or any portion of the
Basic Rent, Additional Rent or other sums and charges at any time paid or
payable hereunder by the Tenant to the Landlord, to any Mortgagees or other
transferees designated by the Landlord in duly recorded instruments, and in any
such case the Tenant shall pay the Basic Rent, Additional Rent and such other
sums and charges so assigned, subject to the terms of the Lease, upon demand to
such Mortgagees and other transferees at the addresses mentioned in and in
accordance with the terms of such instruments provided the Tenant has been
notified in writing of such transfer and provided with such addresses.

21.  MORTGAGEES' RIGHTS

     Subject to the following sentence, the Tenant hereby agrees that this Lease
is and shall be subject and subordinate to any mortgage (and to any amendments,
extensions, increases,

                                       16
<Page>

refinancing or restructuring thereof) of the Property, the Building or the
Premises, whether or not such mortgage is filed subsequent to the execution,
delivery or the recording of this Lease or any notice hereof (the holder from
time to time of any such mortgage being in this Lease sometimes called the
"Mortgagee"). The foregoing subordination shall be as to any mortgage filed
prior or subsequent to the execution and delivery hereof but only if the
Mortgagee agrees in writing pursuant to a commercially customary subordination,
non-disturbance and attornment which provides that, for so long as there exists
no default under this Lease by the Tenant not cured within applicable periods of
notice and grace, the Mortgagee will be bound by the terms of this Lease and
will not, in foreclosing against or taking possession of the Premises or
otherwise exercising its rights under such mortgage, disturb the Tenant's
possession of the Premises hereunder or words of similar import, and which
recognizes the security deposit paid hereunder. The Tenant hereby agrees to
execute, acknowledge and deliver in recordable form such instruments confirming
and evidencing the foregoing subordination as the Landlord or any such Mortgagee
may from time to time reasonably require.

     Provided that the Tenant has been provided with notice of such mortgage and
appropriate addresses to which notice should be sent, no notice from the Tenant
of any default by the Landlord in its obligations shall be valid, and the Tenant
shall not attempt to terminate this Lease, withhold Basic Rent or Additional
Rent or exercise any other remedy which may arise by reason of any such default,
unless the Tenant first gives such notice to all Mortgagees and provides such
Mortgagees with reasonable time after such notice to cure such default (such
reasonable time shall not add more than 30 days to Landlord's cure period). The
Tenant shall and does hereby agree, upon default by the Landlord under any
mortgage, to attorn to and recognize the Mortgagee or anyone else claiming under
such mortgage, including a purchaser at

                                       17
<Page>

a foreclosure sale and, at its request as successor to the interest of the
Landlord under this Lease, to execute, acknowledge and deliver in recordable
form such evidence of this attornment, which shall nevertheless be
self-operative and automatically effective so long as such mortgagee or
successor agrees to be bound by the terms of this Lease and to recognize the
tenancy created hereunder, as the Mortgagee or such successor may request and to
make payments of Basic Rent and Additional Rent hereunder directly to the
Mortgagee or any such successor, as the case may be, upon request. Any such
payments by Tenant to such party shall absolve Tenant from any claim or further
liability by another party related to such payments. Any Mortgagee may, at any
time, by giving written notice to, and without further consent from the Tenant,
subordinate its mortgage to this Lease, and thereupon the interest of the Tenant
under this Lease shall automatically be deemed to be prior to the lien of such
mortgage without regard to the relative dates of execution, delivery or
recording thereof or otherwise.

22.  TENANT'S DEFAULT LANDLORD'S REMEDIES

     If the Tenant shall default in the payment of any Basic Rent or Additional
Rent and such default shall continue for ten (10) days after written notice from
the Landlord; or if the Tenant shall default in the performance or observance of
any of the other covenants contained in this Lease and on the Tenant's part to
be performed or observed and shall fail, within thirty (30) days after written
notice form the Landlord of such default, to cure such default or if such
default is not susceptible of cure within said thirty (30) day period, promptly
to make provision for such cure and thereafter to pursue such cure diligently to
completion; or if the estate hereby created shall be taken on execution, or by
other process of law; or if the Tenant shall be involved in financial
difficulties as evidenced:

                                       18
<Page>

     (1)     by its commencement of a voluntary case under Title 11 of the
             United States Code as from time to time in effect, or by its
             authorizing, by appropriate proceeding of trustees or other
             governing body the commencement of such voluntary case,

     (2)     by its filing an answer or other pleading admitting or failing to
             deny the material allegations of a petition filed against it
             commencing an involuntary case under said Title 11, or seeking,
             consenting to or acquiescing in the relief therein provided, or by
             its failing to controvert timely the material allegations of any
             such petition,

     (3)     by the entry of an order for relief in any involuntary case
             commenced under said Title 11,

     (4)     by its seeking relief as a debtor under any applicable law, other
             than said Title 11, of any jurisdiction relating to the liquidation
             or reorganization of debtors or to the modification or alteration
             of the rights of creditors, or by its consenting to or acquiescing
             in such relief,

     (5)     by the entry of an order by a court of competent jurisdiction (i)
             fording it to be bankrupt or insolvent, (ii) ordering or approving
             its liquidation, reorganization or any modification or alteration
             of the right of its creditors, or (iii) assuming custody of, or
             appointing a receiver or other custodian for, all or a substantial
             part of its property, or

                                       19
<Page>

     (6)     by its making an assignment for the benefit of, or entering into a
             composition with, its creditors, or appointing or consenting to the
             appointment of a receiver or other custodian for all or a
             substantial part of its property;

then and in any of said cases, the Landlord may, to the extent permitted by law,
immediately or at any time thereafter and with reasonable demand and notice,
terminate this Lease and enter into and upon the Premises, or any part thereof
in the name of the whole, and repossess the same as of the Landlord's former
estate, and expel the Tenant and those claiming through or under the Tenant and
remove its effects without being deemed guilty of any manner of trespass, and
without prejudice to any remedies which might otherwise be used for arrears of
rent or preceding breach of covenant.

     No termination or repossession provided for in this Paragraph 22 shall
relieve the Tenant under this Lease of its liabilities and obligations under
this Lease, all of which shall survive any such termination or repossession. In
the event of any such termination or repossession, the Tenant shall pay to the
Landlord either (i) in advance on the first day of each month, for what would
have been the entire balance of the Term, one-twelfth (1/12) (and a pro rata
portion thereof for any fraction of a month) of the Basic Rent, Additional Rent
and all other amounts for which the Tenant is obligated hereunder, less, in each
case, the actual net receipts by the Landlord by reason of any reletting of the
Premises after deducting the Landlord's reasonable expenses in connection with
such reletting, including, without limitation, removal, storage and repair costs
and reasonable brokers' and attorneys' fees, or (ii) at the option of the
Landlord exercisable by the Landlord's giving notice to the Tenant within thirty
(30) days after any such termination, the present value (computed at a
capitalization rate based upon the so-called corporate "Base Rate" then in
effect at The First National Bank of Boston) of the amount by

                                       20
<Page>

which the payments of Basic Rent and the Additional Rent reasonably estimated to
be payable for the balance of the Term after the date of the exercise of said
option would exceed the payments reasonably estimated to be the fair rental
value of the Premises on the terms and conditions of this Lease over such
period, determined as of such date. Landlord shall use reasonable efforts to
relet the Premises for the reasonable rental value thereof and to collect the
rent under such reletting but Landlord shall not be liable for failure to relet
the Premises or in the event that the Premises are relet for failure to collect
the rent under such reletting.

     Without thereby affecting any other right or remedy of the Landlord
hereunder, the Landlord may, at its option, cure for the Tenant's account any
default by the Tenant hereunder which remains uncured after the expiration of
any applicable cure period provided hereunder, and the cost to the Landlord of
such cure shall be deemed to be Additional Rent and shall be paid to the
Landlord by the Tenant with the installment of Basic Rent next accruing.

23.  REMEDIES CUMULATIVE; WAIVERS; ATTORNEY'S FEES

     The specific remedies to which the Landlord or the Tenant may resort under
the terms of this Lease are cumulative and are not intended to be exclusive of
any other remedies or means of redress to which the Landlord or the Tenant may
be lawfully entitled under any provision of this Lease or otherwise. The failure
of the Landlord or the Tenant to insist in any one or more cases upon the strict
performance of any of the covenants of this Lease, or to exercise any option
herein contained, shall not be construed as a waiver or relinquishment for the
future of such covenant or option. A receipt by the Landlord, or payment by the
Tenant, of Basic Rent or Additional Rent with knowledge of the breach of any
covenant hereof shall not be deemed a waiver of such breach, and no waiver,
change, modification or discharge by the Landlord or the Tenant of any provision
in this Lease shall be deemed to have been made or shall be effective

                                       21
<Page>

unless expressed in writing and signed by an authorized representative of the
Landlord or the Tenant as appropriate. In addition to the other remedies in this
Lease provided, the Landlord or the Tenant shall be entitled to the restraint by
injunction of the covenants, conditions or provisions.

     Notwithstanding anything to the contrary herein, in all cases where
attorney fees are incurred in the enforcement of rights by Landlord or Tenant
under this Lease the prevailing party shall be entitled to receive reimbursement
from the other party of its reasonable attorney fees.

24.  EXTENSION OF TERM

     The Tenant shall have the right, as its sole option, by in each instance
giving notice thereof to the Landlord at least nine (9) months prior to the
expiration of the then existing Term, to extend the Term of this Lease for two
(2) additional successive periods of five (5) years each (commencing upon the
expiration of the initial Term) on the same terms and conditions, except Basic
Rent, as herein set forth except that it is understood and agreed that such
extensions shall be exercisable only if at the time of exercise in each case
there exists no default on the part of the Tenant under this Lease which has not
been cured within the time provided for cure hereunder. The failure to give such
notice in a timely fashion shall be deemed an irrevocable election on the part
of the Tenant not to exercise such extension option.

     The Basic Rent during each such extended period shall be the fair market
net rental for the Premises under the terms and conditions of this Lease for a
period of five years determined as of the commencement of such extended period.
Tenant shall notify Landlord not sooner than nine (9) months prior to the
expiration of the then existing Term of its desire to enter into negotiations to
determine Basic Rent for the extended period. If the Landlord and the Tenant are
unable to agree upon the Basic Rent for such extended period at least eight (8)
months prior to its

                                       22
<Page>

commencement, the Basic Rent for such period shall be determined by appraisal as
hereinafter provided. Within ten (10) days after the date for commencement of
appraisal proceedings pursuant to the provisions of this Paragraph 24, the
Landlord and the Tenant shall each simultaneously give writing notice to the
other setting forth its "best offer" for such annual rate of Basic Rent and
designating an Appraiser (as that term is herein after defined). The two
Appraisers so designated shall, within ten (10) days after their designation,
select a third Appraiser and give notice to both the landlord and the Tenant
identifying the third Appraiser. The three Appraisers shall within thirty (30)
days after the selection of the third Appraiser report to the Landlord and the
Tenant in writing, informing them of the annual rate of Basic Rent determined by
them, or by a majority of them, to be payable by the Tenant to the Landlord for
the Premises during such 5-year extended period. The Appraiser's report shall be
accompanied by an explanation of the method used to arrive at the value or
values assigned and the pertinent data (or a summary thereof) considered by the
Appraisers in reaching their decision. All expenses of the appraisal process
(including Appraisers' fees) shall be payable by the party whose "best offer"
set forth in the notice as above provided varied the most from the annual rate
of Basic Rent established in the Appraisers' report. The Appraisers shall advise
the party(ies) which is responsible for the expenses. An "Appraiser" shall be a
person who has an MAI (Member of the Appraisal Institute) designation, is
independent of the Landlord and the Tenant, and has at least eight (8) years'
experience in appraising commercial and industrial real estate in the
metropolitan Boston area.

     Notwithstanding the foregoing procedure, in no event will the Basic Rent be
less than $580,000 per year.

                                       23
<Page>

25.  BROKERAGE

     Landlord shall be responsible for the brokerage fees in connection with
this transaction including Winchester, Avalon and Meredith & Grew. Tenant
represents that its broker is The Winchester Companies, Inc. & Avalon Partners.
Landlord represents its broker is Meredith & Grew, Inc.

26.  NOTICES

     Any notices, approvals, specifications or consents required or permitted
hereunder shall be in writing and mailed, postage prepaid, by registered or
certified mail, return receipt requested, if to the Landlord or to the Tenant at
the address set forth herein for each or after the Term Commencement Date, to
the Tenant at the Premises, with a copy to Katharine E. Bachman, Esq., Hale &
Dorr, LLP, 60 State Street, Boston, MA 02109, and if to any Mortgagee at such
address as it may specify by such notice to the Landlord and the Tenant, or at
such other address as any of them may from time to time specify by like notice
to the others. Any such notice shall be deemed given when received or, if
earlier, when postal records indicate delivery was first attempted.

27.  RECORDING

     The Landlord and the Tenant hereby agree, each at the request of the other
or of any Mortgagee, promptly to execute, acknowledge and deliver in recordable
from short form a notice of lease containing the date of commencement of the
Term and such other information as may from time to time be necessary under the
applicable statutes for the protection of any interest of the Landlord, the
Tenant or any Mortgagee in the Premises of this Lease. Either party may record
such short form Notice of Lease with the appropriate Registry of Deeds.

                                       24
<Page>

28.  ESTOPPEL CERTIFICATES

     The Landlord and the Tenant hereby agree from time to time, each within ten
(10) days' prior written notice from the other or any Mortgagee, to execute,
acknowledge and deliver, without charge, to the other party, the Mortgagee or
any other person designated by the other party, a statement in writing
certifying: that this Lease is unmodified and in full force and effect (or if
there have been modifications, identifying the same by the date thereof and
specifying the nature thereof); that to the knowledge of such party there exist
no defaults (or if there be any defaults, specifying the same); the amount of
the Basic Rent, the dates to which the Basic Rent, Additional Rent and other
sums and charges payable hereunder have been paid; and that such party to its
knowledge has no claims against the other party hereunder except for the
continuing obligations under this Lease (or if such party has any such claims,
specifying the same).

29.  BIND AND INURE: LIMITED LIABILITY OF LANDLORD

     All of the covenants, agreements, stipulations, provisions, conditions and
obligations herein expressed and se forth shall be considered as running with
the land and shall extend to, bind and insure to the benefit of the Landlord and
the Tenant, which terms as used in this Lease shall include their respective
successors and assigns where the context hereof so admits.

     The Landlord shall not have any individual or personal liability for the
fulfillment of the covenants, agreements and obligations of the Landlord
hereunder, the Tenant's recourse and the Landlord's liability hereunder being
limited to the Property and the Building. The term "Landlord" as used in this
Lease shall refer only to the owner or owners from time to time of the Property
or the Building, it being understood that no such owner shall have any liability
hereunder for matters arising from and after the date such owner ceases to have
any interest in the Property or the Building.

                                       25
<Page>

     In no event shall either party be liable to the other party for any
special, consequential or indirect damages suffered by either party or any other
person or entity by reason of a default by either party under any provisions of
this Lease.

30.  CAPTIONS

     The captions for the numbered Paragraphs of this Lease are provided for
reference only, and they do not constitute a part of this agreement or any
indication of the intentions of the parties hereto.

31.  INTEGRATION

     The parties acknowledge that all prior written and oral agreements between
them and all prior representations made by either party to the other have been
incorporated in this instrument or otherwise satisfied prior to the execution
hereof.

32.  HAZARDOUS, TOXIC SUBSTANCES

     Tenant shall not cause or authorize any hazardous or toxic wastes,
hazardous or toxic substances or hazardous or toxic materials (collectively,
"Hazardous Materials") to be used, generated, stored or disposed of on,
transported to or from, the Premises (collectively, "Hazardous Materials
Activities") except in material compliance (at Tenant's expense) with all
applicable Regulations, as hereinafter defined. Landlord shall not be liable to
Tenant for any loss, cost, expense, claims, damage or liability arising out of
any Hazardous Materials Activities by Tenant, Tenant's employees, agents,
contractors, licensees, or invitees. Tenant shall indemnify, defend with counsel
reasonably acceptable to Landlord, and hold Landlord harmless from and against
any and all loss, cost, expense, claims, damage and liability arising out of all
Hazardous Materials Activities on the Premises caused by or arising out of any
act or omission

                                       26
<Page>

of Tenant, Tenant's employees, agents, contractors, licensees or invitees. For
purposes hereof, Hazardous Materials shall include but not limited to substances
defined as "hazardous substances", "toxic substances", or "hazardous wastes" in
the federal Comprehensive Environmental Response, Compensation and Liability Act
of 1980, as amended; the federal Hazardous Materials Transportation Act, as
amended; and the federal Resource Conservation and Recovery Act, as amended
("RCRA"); those substances defined as "hazardous wastes" in the Massachusetts
Hazardous Waste Facility  ing Act, as amended (Massachusetts General Laws
Chapter 21D): those substances defined as "hazardous materials" or "oil" in
Massachusetts General Laws Chapter 21E, as amended; and as such substances are
defined in any regulations adopted and publications promulgated pursuant to any
of said laws (collectively, "Regulations"). If Tenant's activities violate any
Regulations, Tenant shall cease such activities immediately upon notice from
Landlord. Tenant shall immediately notify Landlord both by telephone and in
writing of any spill, discharge, release or exposure of Hazardous Materials in
the Premises in violation of law or of any condition in the Premises
constituting an "imminent hazard" under any Regulations. After notice to Tenant,
Landlord may disclose any spill, discharge, release, or exposure or any
violation of any Regulations to any governmental agency with jurisdiction.
Notwithstanding the foregoing, Tenant shall have no obligation or liability for
any loss, cost, expense, claims, damage or liability with respect to any spill,
discharge, release or exposure of Hazardous Materials or of any violation of any
Regulations with respect to Hazardous Materials or of any Hazardous Materials
Activities occurring at or migrating to or from the Premises prior to Tenant's
entry upon the Premises, nor as to any Hazardous Materials which migrate onto
the Premises from other property, whether prior to or during the Term, and
Landlord shall indemnify and hold Tenant harmless from and against any loss,
cost, expense or costs of defense in any

                                       27
<Page>

enforcement actions and costs of clean-up and remediation arising as a result of
any such spill, discharge, release, exposure, violation or other Hazardous
Materials Activities.

     Tenant shall promptly provide all reasonable information regarding the use,
generation, storage, transportation or disposal of Hazardous Substances that is
requested by Landlord. If Tenant fails to fulfill any duty imposed under this
Paragraph, within a reasonable time, Landlord may do so; and in such case,
Tenant shall cooperate with Landlord in order to prepare all documents Landlord
reasonably deems necessary or appropriate to determine the applicability of the
Regulations to the Premises and Tenant's use thereof, and for compliance
therewith, and Tenant shall execute all documents promptly upon Landlord's
request. No such action by Landlord and no attempt made by Landlord to mitigate
damages under any Regulation shall constitute a waiver of any of Tenant's
obligations under this paragraph.

33.  FINANCIAL STATEMENTS

     Tenant shall deliver to Landlord with reasonable promptness, but in no
event later than 135 days after the close of each fiscal year, financial reports
of Tenant prepared in accordance with generally accepted accounting principles.
Such financial reports shall be its audited statements if available, or shall be
certified by a corporate officer. Also, if requested by Landlord, Tenant shall
provide to Landlord its most recent quarterly financial reports. Any financial
reports provided to Landlord under this Section 33 shall be considered
confidential information and shall only be disclosed by Landlord in connection
with obtaining or attempting to obtain financing or a sale of the Premises.
Landlord shall require the party to whom the information is disclosed to agree
to keep such financial reports confidential.

                                       28
<Page>

34.  SEVERABILITY: CHOICE OF LAW,

     If any provision of this Lease shall be declared to be void or
unenforceable either by law or by a court of competent jurisdiction, the
validity or enforceability of remaining provisions shall not thereby be
affected.

35.  SECURITY DEPOSIT

     At the time of the execution hereof, Tenant shall pay to Landlord a
security deposit in the amount of $100,000 which may be an irrevocable letter of
credit drawn on Bank and in a form reasonably satisfactory to the Landlord. The
Landlord may apply the deposit from time to time to cure any default of Tenant
hereunder not cured after applicable notice and grace periods. Tenant shall have
no right to require the Landlord to so apply said security deposit, nor shall
Tenant be entitled to credit the same against rents or other sums payable
hereunder. If and to the extent that the Landlord makes such use of the security
deposit, or any part thereof, the sum so applied by Landlord shall be restored
to the security deposit by Tenant upon ten (10) days written notice from
Landlord, and failure to pay to Landlord the amount to be so restored shall be a
default hereunder giving rise to all of the Landlord's rights and remedies
applicable to a default in the payment of rent. The Security Deposit, if any, or
any balance thereof after Application of the Security Deposit to uncured
defaults of Tenant, shall be returned to Tenant within 30 days after expiration
of the Lease Term or termination of the same and after delivery of possession of
the entire Premises to Landlord.

     This Lease is made under, and shall be construed in accordance with, the
laws of the Commonwealth of Massachusetts.

     IN WITNESS WHEREOF, the parties hereto have caused this instrument to be
executed in duplicate under seal as of the date first above written.

                                       29
<Page>

LANDLORD:

By: /s/ William J. Callahan
    ------------------------
    William J. Callahan

TENANT:
NitroMed, Inc.

By:  /s/ Manuel Worcel, M.D
     ------------------------------
    President & CEO

                                       30
<Page>

                                     BEDFORD

                                    EXHIBIT A

A certain parcel of land shown as Lot 16 on a plan of land entitled "Land Court
Plan of Land in Bedford, Mass." dated March 18, 1983 by Joseph W. Moore Co.,
filed with Middlesex South Registry District of the Land Court as Plan Number
11345J bounded and described as follows:

      Northerly         by Oak Park Drive, 90.00 feet;

      Northwesterly     by Lot 11 on Land Court Plan 11345H, 424.48 feet;

      Southwesterly     by Lot 15 on the Plan first mentioned above, 94.55 feet;

      Southerly         by Land now or formerly of R & W Realty Trust a total of
                        405.21 feet;

      Southeasterly     by Lot 2 on Land Court Plan 11345C, 240.00 feet;

      Northeasterly     by Lot 9 on Land Court Plan 11345 H, 269.16 feet; and

      Easterly          by said Lot 9, 123.58 feet.

Being a portion of the premises described in Middlesex South Registry District
of the Land Court Certificate of Title 167179, in Registration Book 966,
Page 29.

<Page>

                     NONDISTURBANCE AND ATTORNMENT AGREEMENT

     This is a Nondisturbance and Attornment Agreement dated this 30th day of
April, 1997 by and between William J. Callahan, Jr. and Joan/ Callahan, Trustees
of WJCC Realty Trust under declaration of trust dated January 31, 1983,
registered with the Middlesex South Registry of District of the Land Court as
Document No. 635483 ("Ground Lessor") and NitroMed, Inc., a Delaware corporation
("Tenant").

                                   WITNESSETH

     WHEREAS, Ground Lessor is the owner in fee simple of certain premises
located at 12 Oak Park Drive, Bedford, Middlesex County, Massachusetts, more
particularly described in Exhibit A attached hereto ("Demised Premises"); and

     WHEREAS, under a lease dated January 31, 1983 between Ground Lessor and
William J. Callahan ("Landlord"), a notice of which is filed for registration
with said Registry District as Document No. 648251, Ground Lessor did lease, let
and demise the Demised Premises to Landlord; and

     WHEREAS, under a lease dated as of May 29, 1997 ("Sublease"), Landlord did
lease, let and demise to Tenant, subject to said Ground Lease, the Demised
Premises; and

     WHEREAS, the parties hereto desire to establish additional rights of quiet
and peaceful possession for the benefit of Tenant under the said Sublease and
further to define the terms, covenants and conditions precedent for such
additional rights.

     NOW, THEREFORE, in consideration of the respective demises and other good
and valuable consideration, the receipt and sufficiency of which is hereby
acknowledged, each to the other in hand paid, it is hereby mutually covenanted
and agreed as follows:

     1.   That Ground Lessor consents to and approves the Sublease.

     2.   That in the event of the event of the cancellation or termination of
the said Ground Lease or of the surrender thereof, whether voluntary,
involuntary or by operation of law, prior to the expiration of the said
Sublease, and subject to the observance and performance by Tenant of all of the
terms, covenants and conditions of the said Sublease on the part of Tenant to be
observed and performed, Ground Lessor does hereby warrant as follows:

          (a)  The quiet and peaceful possession of Tenant under the said
               Sublease.

          (b)  That the Sublease shall continue in full force and effect and
               Ground Lessor shall recognize the Sublease and Tenant's rights
               thereunder and will thereby establish direct privity of estate
               and contract as between Ground Lessor and Tenant, with the same
               force and effect and with the same relative priority in time and
               right as though the Sublease were originally made directly from
               Ground Lessor in favor of Tenant.

<Page>

          (c)  To assume all of the obligations on the part of Landlord under
               the Sublease.

But in no event shall the person who is at any time Ground Lessor, or any
trustee, shareholder or beneficiary of any trust who is at any time Ground
Lessor, be personally liable for the performance of any obligations, expressed
or implied in such Sublease, and Tenant shall look solely to the interest of
Ground Lessor at the time of the breach of any obligation in the premises leased
to Landlord in the Ground Lease for satisfaction of the obligations of Landlord
to Tenant under the Sublease. Only the person who is at the time Ground Lessor
shall have any liability for breaches of obligations for which Ground Lessor is
at the time liable under the terms of the Sublease.

     3.   That in the event of the cancellation or termination of the said
Ground Lease or of the surrender thereof, whether voluntary, involuntary or by
operation of law, prior to the expiration date of the said Sublease, including
any extensions and renewals of said Sublease, Tenant hereby covenants and agrees
to make full and complete attornment to Ground Lessor for the balance of the
term of the Sublease, including any extensions and renewals thereof, now
provided thereunder, upon the same terms, covenants and conditions as provided
in the Sublease, so as to establish direct privity of estate and contract as
between Ground Lessor and Tenant and with the same force and effect and relative
priority in time and right as though the Sublease were originally made directly
from Ground Lessor to Tenant, and Tenant will thereafter make all rent payments
directly to Ground Lessor.

     4.   That the terms, covenants and conditions hereof shall inure to the
benefit of and be binding upon the respective parties hereto, their respective
heirs, executors, administrators, successors, transferees and designees.

                                        2
<Page>

     IN WITNESS WHEREOF, the parties hereto have caused this writing to be
signed, sealed and delivered in their respective names and behalf, and, if a
corporation, by its officers duly authorized, the day and year first above
written.

                                   GROUND LESSOR:

                                   /s/ William J. Callahan, Jr.
                                   ---------------------------------------------
                                   William J. Callahan, Jr., as Trustee
                                   aforesaid

                                   /s/ Joan M. Callahan
                                   ---------------------------------------------
                                   Joan M Callahan, as Trustee
                                   aforesaid

                                   TENANT:

                                   NITROMED, INC.

                                   By:     /s/ Manuel Worcel, M.D
                                           -------------------------------------
                                           Name: Manuel Worcel, M.D
                                           Its: President and Chief Executive

                          COMMONWEALTH OF MASSACHUSETTS

Middlesex, ss.                                                   April 30, 1997

     Then personally appeared the above named William J. Callahan, Jr. and Joan
M. Callahan as Trustee aforesaid, and acknowledged the foregoing to be their
free act and deed before me.

                                   /s/ illegible
                                   ---------------------------------------------
                                   Notary Public
                                   My commission expires:
                                   September 11, 1998

                                        3
<Page>

                          COMMONWEALTH OF MASSACHUSETTS

Suffolk, ss.                                                     April 30, 1997

     Then personally appeared the above named Manuel Worcel M.D. the President
of NitroMed, Inc., and acknowledged the foregoing to be the free act and deed of
NitroMed, Inc., before me.

                                   /s/ Judith Maloney Boyle
                                   ---------------------------------------------
                                   Notary Public
                                   My commission expires: May 15, 2003

                                        4
<Page>

             SUBORDINATION, NONDISTURBANCE, AND ATTORNMENT AGREEMENT

                                   (MORTGAGE)

     This SUBORDINATION, NONDISTURBANCE, AND ATTORNMENT AGREEMENT ("Agreement")
is made as of August 7, 1997, by and among FLEET NATIONAL BANK, as Trustee, of
the Hartford Life Insurance Company and Hartford Life and Accident Insurance
Company, Commercial and Multifamily Mortgage Pass-Through Certificates, Series
1996-1 with a place of business at 777 Main Street, Hartford, Connecticut 06115,
Attention: Corporate Trust Administration-MSN 238 ("Lender"), WILLIAM J.
CALLAHAN, an individual and WILLIAM J. CALLAHAN, JR. AND JOAN M. CALLAHAN,
TRUSTEES OF THE WJCC REALTY TRUST, having an address of c/o P.O. Box 269,
Bedford, Massachusetts ("Landlord"), and NITROMED, INC., a Delaware corporation
with a place of business as stated in the Lease, defined below ("Tenant").

     A.   Tenant has entered into a certain lease dated May 29,1997 (as amended
to date, the "Lease") with William J. Callahan covering certain premises (the
"Premises") at the property located at 12 Oak Park Drive, Bedford, Massachusetts
as further described in EXHIBIT A attached hereto and incorporated herein by
reference (the "Property").

     B.   Hartford Life Insurance Company, upon certain terms and conditions,
made a loan to Landlord (the "Loan") secured in part by a mortgage of the
Property (the "Mortgage") and in part by other security instruments (the
Mortgage and such other security instruments, collectively, the "Loan
Documents").

     C.   Hartford Life Insurance Company transferred its interest in the
Mortgage to Fleet National Bank, as Trustee, of the Hartford Life Insurance
Company and Hartford Life and Accident Insurance Company, Commercial and
Multifamily Mortgage Pass-Through Certificates, Series 1996-1. For purposes of
this Agreement Fleet National Bank shall hereinafter be referred to as the
Lender.

     D.   The parties desire to set forth their agreement.

     NOW, THEREFORE, in consideration of the premises and of other good and
valuable consideration, the receipt and adequacy whereof is hereby acknowledged,
the parties hereby covenant and agree as follows:

     1.   SUBORDINATION. The Lease and all rights created thereby are and shall
be subject and subordinate to the Loan Documents and to any and all renewals,
modifications, consolidations, replacements, and extensions thereof and all
advancements made thereunder, to the full extent of all sums due to Lender. The
Loan Documents shall take priority over the Lease and shall be entitled to the
same rights and privileges, both at law and in equity, as the Loan Documents
would have had if they had been executed, delivered, and recorded prior to the
execution, delivery, or recording of the Lease.

     2.   NON-DISTURBANCE. If Lender succeeds to the interest of Landlord under
the Lease, Lender shall not disturb Tenant's possession of the Premises or its
rights under the Lease, and the Lease shall continue as a lease between Tenant
and Lender. Lender shall not join Tenant in

<Page>

summary or foreclosure proceedings, provided the Lease is then in full force and
effect and Tenant is not in default thereunder.

     3.   ATTORNMENT. Tenant agrees that, following foreclosure or any deed in
lieu of foreclosure, it will attorn to, and recognize as its landlord, Lender or
any purchaser at a foreclosure sale and their respective successors and assigns
for the unexpired balance of the term of the Lease (and any extensions, if
exercised) upon the same terms and conditions as are set forth in the Lease.
This agreement shall be effective without further written agreement, but, on
request of Lender, Tenant agrees to execute and deliver an agreement of
attornment of similar import to this Agreement. Tenant agrees that foreclosure
of the Mortgage will not be a constructive eviction of Tenant. Tenant shall not
join, appear, or petition to become a party in any foreclosure action.

     4.   LIABILITY OF LENDER. If Lender succeeds to the interest of Landlord
under the Lease, Lender shall assume and perform (but only while the owner of
the Property) all of Landlord's obligations under the Lease, except that Lender
shall not be:

          (a)  liable for any action or omission of any prior landlord,
               including the present Landlord;

          (b)  liable for the return of any security deposit not actually
               received by Lender;

          (c)  subject to any offsets or defenses which Tenant might have
               against any prior landlord, including the present Landlord;

          (d)  bound by any rent or additional rent which Tenant might have paid
               for more than the then current month to any prior landlord,
               including the present Landlord; or

          (e)  bound by any assignment, surrender, termination, cancellation,
               amendment, or modification of the Lease made without its express
               written consent.

     5.   NOTICE AND RIGHT TO CURE. Tenant agrees to give Lender at the time
given to Landlord a copy of any notice of default served upon Landlord. If
Landlord fails to cure such default within the time provided for in the Lease,
Lender shall have the right, but not the obligation, to cure such default within
a reasonable time (but in no event less than 30 days), or if such default cannot
be cured within such reasonable time, then such additional time as may be
necessary to cure such default, provided Lender has commenced and is diligently
pursuing the remedies necessary to cure such default (including, without
limitation, commencement of foreclosure proceedings if necessary to effect such
cure). In such event, the Lease shall not be terminated or the rights of
Landlord under the Lease forfeited or adversely affected during such reasonable
time or while Lender diligently pursues such remedies.

     6.   ASSIGNMENT OF LEASE. Tenant acknowledges that the Lease is being
assigned to Lender under the Loan Documents. The interest of Landlord in the
Lease is being assigned to Lender, but Lender assumes no duty, liability, or
obligation whatever under the Lease. All rent

                                        2
<Page>

payments under the Lease shall continue to be paid to Landlord in accordance
with the terms of the Lease unless and until Lender directs Tenant otherwise in
writing. Upon receipt of such direction from Lender, Tenant agrees to pay all
rent payments to Lender, and Landlord agrees to indemnify Tenant for any rent
payments made to Lender at Lender's direction. Under the provisions of the
assignment, Tenant understands that, without the consent of Lender, the Lease
cannot be amended or terminated (either directly or by the exercise of any
option which could lead to termination) and consent cannot be given to the
release of any party having liability thereon.

     7.   AMENDMENTS. No modification, amendment, waiver, or release of any
provisions of this Agreement or of any right, obligation, claim, or cause of
action arising hereunder shall be valid or binding for any purpose whatsoever
unless in writing and duly executed by the party against which the same is
sought to be asserted.

     8.   NOTICES. All notices, directions, demands, requests, permissions,
approvals, consents, elections or other communications permitted or required to
be given hereunder (singly, a "notice" or collectively, "notices") shall be in
writing, shall be effective for all purposes if hand delivered or sent by
expedited prepaid delivery service (either commercial or United States Postal
Service) with proof of delivery, and shall be deemed given on the date of actual
receipt by the entity to which it is directed, notwithstanding any further
direction to the attention of any individual or department; provided that where
provision is made for the attention of any individual or department, the notice
shall be effective only if the envelope or other wrapper in which it is sent is
addressed in accordance with such provision. Notices shall be addressed to any
party hereto at its address first above written. Any address or name specified
above may be changed by a notice given in accordance with this Section. The
inability to deliver because of a changed address of which no notice was given,
rejection, or other refusal to accept any notice shall be deemed to be the
receipt of the notice as of the date of such inability to deliver, rejection, or
refusal to accept.

     9.   SUCCESSORS AND ASSIGNS.  The terms of this Agreement shall be binding
upon, inure to the benefit of, and be enforceable by, the parties and their
respective successors and assigns.

     IN WITNESS WHEREOF, the parties have caused this Agreement to be duly
executed as of the date first above written.

            [Signatures of the parties appear on the following page]

                                        3
<Page>

Witnessed by:                Lender:

                             FLEET NATIONAL BANK, as Trustee, as Trustee,
                             of the Hartford Life Insurance Company and
                             Hartford Life and Accident Insurance
                             Company, Commercial and Multifamily Mortgage
                             Pass-Through Certificates, Series 1996-1

                             By: Hartford Life Insurance Company
                                 a Connecticut corporation
                                 Master Servicer

                             By: /s/ William W. Malchodi, Jr.
--------------------------       Its Vice President and Director of Taxes

                             By: /s/ J. Richard Garrett
--------------------------       Its Vice President and Assistant Treasurer

                             Borrower:

                             WILLIAM J. CALLAHAN, an Individual

                                 /s/ William J. Callahan
--------------------------   ----------------------------------------

--------------------------
                             WILLIAM J. CALLAHAN, JR., TRUSTEE OF THE WJCC TRUST

                             /s/ William J. Callahan Jr. Trustee
--------------------------   ----------------------------------------

--------------------------

                             JOAN M. CALLAHAN, TRUSTEE OF THE WJCC TRUST

                             /s/ Joan M. Callahan   Trustee
--------------------------   ----------------------------------------

--------------------------

                             Tenant:  NITROMED, INC.

                             By:  /s/ Manuel Worcel, M.D
--------------------------   ----------------------------------------
                                  Its President

--------------------------

                                        4
<Page>

STATE OF CONNECTICUT        )
                            )      SS. HARTFORD
COUNTY OF HARTFORD          )

     Before me, the undersigned, this 7th day of August, 1997, personally
appeared William B. Malchodi, Jr., known to me to be a Vice President and
Director of Taxes of Hartford Life Insurance Company, Master Servicer for FLEET
NATIONAL BANK, as Trustee, of the Hartford Life Insurance Company and Hartford
Life and Accident Insurance Company, Commercial and Multifamily Mortgage
Pass-Through Certificates, Series 1996-1, and that he as such officer, signer
and sealer of the foregoing instrument, acknowledged the execution of the same
to be his free act and deed individually and as such officer, and the free act
and deed of said corporation.

     In Witness Whereof, I hereunto set my hand.

                                         /s/ Janice R. Shea
                                         --------------------------------------
                                         Notary Public
                                         My commission expires: August 31, 1997

STATE OF CONNECTICUT        )
                            )      SS. HARTFORD
COUNTY OF HARTFORD          )

     Before me, the undersigned, this 7th day of August, 1997, personally
appeared J. Richard Garrett known to me to be a Vice President and Assistant
Treasurer of Hartford Life Insurance Company, Master Servicer for FLEET NATIONAL
BANK, as Trustee, of the Hartford Life Insurance Company and Hartford Life and
Accident Insurance Company, Commercial and Multifamily Mortgage Pass-Through
Certificates, Series 1996-1, and that he as such officer, signer and sealer of
the foregoing instrument, acknowledged the execution of the same to be his free
act and deed individually and as such officer, and the free act and deed of said
corporation.

     In Witness Whereof, I hereunto set my hand.

                                         /s/ Janice R. Shea
                                         --------------------------------------
                                         Notary Public
                                         My commission expires: August 31, 1997

                                        5
<Page>

COMMONWEALTH OF MASSACHUSETTS  )
                               )   SS. _____________
COUNTY OF MIDDLESEX            )

     Before me, the undersigned, this 30th day of June, 1997, personally
appeared William J. Callahan, an individual, signer and sealer of the foregoing
instrument, who acknowledged the execution of the same to be his free act and
deed.

     In Witness Whereof, I hereunto set my hand.

                                   /s/ Daniel F. (illegible)
                                   ---------------------------------------
                                   Notary Public
                                   My Commission Expires: Sept. 11, 1998

COMMONWEALTH OF MASSACHUSETTS  )
                               )   SS. _____________
COUNTY OF MIDDLESEX            )

     Before me, the undersigned, this 30 day of June, 1997, personally appeared
William J. Callahan, Jr., Trustee of the WJCC Realty Trust, and that he as such
Trustee, signer and sealer of the foregoing instrument, acknowledged the
execution of the same to be his free act and deed as such Trustee and the free
act and deed of said Trust.

     In Witness Whereof, I hereunto set my hand.

                                   /s/ Daniel F. (illegible)
                                   ---------------------------------------
                                   Notary Public
                                   My Commission Expires: Sept. 11, 1998

COMMONWEALTH OF MASSACHUSETTS  )
                               )   SS. _____________
COUNTY OF MIDDLESEX            )

     Before me, the undersigned, this 30 day of June, 1997, personally appeared
Joan M. Callahan, Jr., Trustee of the WJCC Realty Trust, and that he as such
Trustee, signer and sealer of the foregoing instrument, acknowledged the
execution of the same to be his free act and deed as such Trustee and the free
act and deed of said Trust.

     In Witness Whereof, I hereunto set my hand.

                                   /s/ Daniel F. (illegible)
                                   ---------------------------------------
                                   Notary Public
                                   My Commission Expires: Sept. 11, 1998

                                        6
<Page>

STATE OF MASSACHUSETTS         )
                               )   SS. _____________
COUNTY OF SUFFOLK              )

     Before me, the undersigned, this 5th day of June, 1997, personally appeared
Manuel Worcel, known to me to be the President of NITROMED, INC., a corporation,
and that he/she as such officer, signer and sealer of the foregoing instrument,
acknowledged the execution of the same to be his/her free act and deed
individually and as such officer, and the free act and deed of said corporation.

     In Witness Whereof, I hereunto set my hand.

                                   /s/ Judith Maloney Boyle
                                   ---------------------------------------
                                   Notary Public
                                   My Commission Expires: May 15, 2003

                                        7QuickLinks
 -- Click here to rapidly navigate through this document

 
 

EXHIBIT 10.38    
    

 
 

FOURTH AMENDMENT TO LEASE AGREEMENT    
    

        THIS FOURTH AMENDMENT TO LEASE AGREEMENT (this "Fourth Amendment")
is made as of the 28th day of February, 2003 by and between WEST 78th STREET BLOOMINGTON ASSOCIATES, LLC
("Landlord") and AUGUST TECHNOLOGY CORPORATION ("Tenant").

 
 

R E C I T A L S:    
    

        A.    Landord
and Tenant entered into that certain Lease Agreement dated October 18, 1999 (the "Original Lease") as
amended by (i) that certain First Amendment to Lease Agreement dated March 31, 2000 (the "First Amendment"), (ii) that certain
Second Amendment to Lease Agreement dated July 25, 2000 (the "Second Amendment") and (iii) that certain Third Amendment to Lease Agreement
dated June 18, 2001 (the "Third Amendment"; the Original Lease as amended by the First Amendment, the Second Amendment and the Third Amendment is
referred to herein as the "Lease") demising approximately 78,437 square feet of space comprised of the "Initial Premises," the "First Expansion
Premises," the "Second Expansion Premises" and the "Third Expansion Premises" (collectively, the "Existing Premises") in the building located at 4900 W.
78th Street in Bloomington, Minnesota. 

        B.    Landlord
and Tenant desire to make certain changes to the Lease as provided herein. 

        NOW, THERFORE, in consideration of the mutual covenants contained herein and other good and valuable consideration the receipt and
sufficiency of which are hereby acknowledged, Landlord and Tenant hereby amend the Lease as follows: 

        1.     Definitions. Each capitalized term used as a defined term in this Fourth Amendment but not otherwise defined in this
Fourth Amendment shall have the same meaning ascribed to such term in the Lease. 

        2.     Third Expansion Premises. Effective as of the date of this Fourth Amendment, the following modifications are made with
respect to Tenant's leasing of the Third Expansion Premises: 

	(a)
	The
$4,873.13 credit against monthly Base Rent for the Third Expansion Premises that is set forth in Section 3(d) of the Third Amendment is hereby extended until
February 29, 2004 (i.e., such $4,873.13 credit shall continue to be applied against monthly Base Rent for the Third Expansion Premises from the Third Expansion Premises Credit Termination Date
through and including February 2004).

	(b)
	The
Third Expansion Premises Construction Allowance is hereby reduced from $15.00 per foot to $11.25 per foot.

	(c)
	The
last sentence of Section 3(f) of the Third Amendment is herby deleted and the following sentence is substituted in its place: 

This
amount shall be applied evenly, without interest, over the period between the first day of the first calendar month after Tenant notifies Landlord of such election and the Expiration Date. 

        3.     No Offer. Submission of this instrument for examination or negotiation shall not bind Landlord or Tenant, and no
obligation on the part of Landlord or Tenant shall arise until this instrument is signed and delivered by Landlord and Tenant. 

        4.     Lease in Full Force and Effect. Except as herein provided, all of the terms and provisions of the Lease shall remain in
full force and effect. All capitalized terms used in this Fourth Amendment shall have the definition given to them in the Lease unless otherwise defined herein. 

        IN WITNESS WHEREOF, the parties hereto have caused this Fourth Amendment to Lease Agreement to be duly executed and delivered as of the
day and year first written above. 

	LANDLORD:	 	 	 	TENANT:
	
WEST 78TH STREET

BLOOMINGTON ASSOCIATES, LLC	
 	

 	
 	

AUGUST TECHNOLOGY

CORPORATION
 
	
BLOOMINGTON OFFICE PROJECT, LLC,

Its Manager	
 	

 	
 	

 

	

By	
 	

/s/  TIMOTHY M. GRAY      
 Its Chief Manager	
 	

 	

By	
 	

/s/  DAVID L. KLENK      
Its President

QuickLinks

EXHIBIT 10.38

FOURTH AMENDMENT TO LEASE AGREEMENT

R E C I T A L S

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00055-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00055-of-00352.parquet"}]]