EMPLOYMENT AGREEMENT

     This Employment Agreement (“Agreement”) is made as of the 8th day of March,
2010, between CombinatoRx, Incorporated, a Delaware corporation (the “Company”),
and Mark H.N. Corrigan, M.D. (the “Executive”).

     WHEREAS, the Company desires to employ the Executive and the Executive
desires to be employed by the Company beginning on January 5, 2010 (the
“Commencement Date”) on the terms contained herein.

     NOW, THEREFORE, in consideration of the mutual covenants and agreements
herein contained and other good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the parties agree as follows:

     1. Position and Duties. The Executive shall serve as the Chief Executive
Officer and President of the Company, and shall have supervision and control
over and responsibility for the day-to-day business and affairs of the Company
and shall have such other powers and duties as may from time to time be
prescribed by the Chairman of the Board of Directors of the Company (the
“Board”), provided that such duties are consistent with the Executive’s position
or other positions that he may hold from time to time. The Executive shall
report to the Board of Directors of the Company. The Executive’s primary place
of employment with the Company shall be the Company’s headquarters in Cambridge,
Massachusetts. The Executive shall devote his full working time and efforts to
the business and affairs of the Company. Notwithstanding the foregoing, the
Executive may serve on other boards of directors, with the approval of the
Board, or engage in religious, charitable or other community activities as long
as such services and activities are disclosed to the Board and do not materially
interfere with the Executive’s performance of his duties to the Company as
provided in this Agreement.

2.      Compensation and Related Matters.     (a) Base Salary. The Executive’s
initial annual base salary shall be $450,000.  

The Executive’s base salary shall be subject to annual review by the
Compensation Committee but shall not be reduced below $450,000 per annum. The
base salary in effect at any given time is referred to herein as “Base Salary.”
The Base Salary shall be payable in a manner that is consistent with the
Company’s usual payroll practices for senior executives.

     (b) Incentive Compensation. The Executive shall be eligible to receive cash
incentive compensation as determined by the Compensation Committee from time to
time. The Executive’s initial target annual incentive compensation shall be 50
percent of his Base Salary. The Executive’s target annual incentive compensation
shall be reset annually but shall not be reduced below 50 percent of his Base
Salary. To earn incentive compensation, the Executive must be employed by the
Company on the day such incentive compensation is paid.

     (c) Expenses. The Executive shall be entitled to receive prompt
reimbursement for all reasonable expenses incurred by him before the termination
of his employment in performing services hereunder, in accordance with the
policies and procedures then in effect and established by the Company for its
senior executive officers. Notwithstanding

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

the foregoing, the Company shall reimburse the Executive for all reasonable
travel (which shall be deemed to include Business Class (or First Class if
Business Class is not offered) airfare), entertainment and other expenses
incurred or paid by the Executive before the termination of his employment
hereunder in connection with, or related to, the performance of his Chief
Executive Officer and President of the Company duties, responsibilities or
services under this Agreement.

     (d) Other Benefits. The Executive shall be entitled to participate in or
receive benefits under all of the Company’s Employee Benefit Plans in effect on
the date hereof, or under plans or arrangements that provide the Executive with
benefits at least substantially equivalent to those provided under such Employee
Benefit Plans. As used herein, the term “Employee Benefit Plans” includes,
without limitation, each pension and retirement plan; supplemental pension,
retirement and deferred compensation plan; savings and profit-sharing plan;
stock ownership plan; stock purchase plan; stock option plan; life insurance
plan; medical insurance plan; disability plan; and health and accident plan or
arrangement established and maintained by the Company on the date hereof for
employees of the same status within the hierarchy of the Company.
Notwithstanding the foregoing, the Executive shall be entitled to participate in
or receive benefits under any employee benefit plan or arrangement which may, in
the future, be made available by the Company to him as Chief Executive Officer
and President of the Company or to its executives and key management employees,
subject to and on a basis consistent with the terms, conditions and overall
administration of such plan or arrangement. Any payments or benefits payable to
the Executive under a plan or arrangement referred to in this Section 2(d) in
respect of any calendar year during which the Executive is employed by the
Company for less than the whole of such year shall, unless otherwise provided in
the applicable plan or arrangement, be prorated in accordance with the number of
days in such calendar year during which he is so employed. Should any such
payments or benefits accrue on a fiscal (rather than calendar) year, then the
proration in the preceding sentence shall be on the basis of a fiscal year
rather than calendar year. The Company, however, reserves the right to modify,
terminate, or replace its employee benefit plans and policies.

     (e) Vacations. The Executive shall be entitled to four weeks’ vacation each
year and the standard paid holidays observed by the Company. For calendar year
2010, the Company and the Executive acknowledge and agree the Executive is
entitled to four weeks of vacation beginning January 27, 2010.

     3. Termination. The Executive’s employment hereunder may be terminated
without any breach of this Agreement under the following circumstances:

    (a)    Death. The Executive’s employment hereunder shall terminate upon his 
death.                (b)    Disability. The Company may terminate the
Executive’s employment if 

he is disabled and unable to perform the essential functions of the Executive’s
then existing position or positions under this Agreement with or without
reasonable accommodation for a period of 180 days (which need not be
consecutive) in any 12-month period. If any question shall arise as to whether
during any period the Executive is disabled so as to be unable to perform the
essential functions of the Executive’s then existing position or positions with
or without reasonable accommodation, the Executive may, and at the request of
the Company shall,

2

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

submit to the Company a certification in reasonable detail by a physician
selected by the Company to whom the Executive or the Executive’s guardian has no
reasonable objection as to whether the Executive is so disabled or how long such
disability is expected to continue, and such certification shall for the
purposes of this Agreement be conclusive of the issue. The Executive shall
cooperate with any reasonable request of the physician in connection with such
certification. If such question shall arise and the Executive shall fail to
submit such certification, the Company’s determination of such issue shall be
binding on the Executive. Nothing in this Section 3(b) shall be construed to
waive the Executive’s rights, if any, under existing law including, without
limitation, the Family and Medical Leave Act of 1993, 29 U.S.C. §2601 et seq.
and the Americans with Disabilities Act, 42 U.S.C. §12101 et seq.

     (c) Termination by Company for Cause. The Company may terminate the
Executive’s employment hereunder for Cause by a vote of the Board at a meeting
of the Board called and held for such purpose. For purposes of this Agreement,
“Cause” shall mean: (i) the Executive’s conviction of a felony; (ii) the
Executive’s willful failure to perform (other than by reason of disability), or
gross negligence in the performance of, the Executive’s duties and
responsibilities, which failure or negligence continues or remains uncured after
30 days’ written notice to the Executive setting forth in reasonable detail the
nature of such failure or negligence; (iii) material breach by the Executive of
any provision of any agreement between the Executive and the Company, which
breach continues or remains uncured after 30 days’ written notice to the
Executive setting forth in reasonable detail the nature of such breach; or (iv)
material fraudulent conduct by the Executive with respect to the Company.

     (d) Termination Without Cause. The Company may terminate the Executive’s
employment hereunder at any time without Cause. Any termination by the Company
of the Executive’s employment under this Agreement which does not constitute a
termination for Cause under Section 3(c) and does not result from the death or
disability of the Executive under Section 3(a) or (b) shall be deemed a
termination without Cause.

     (e) Termination by the Executive. The Executive may terminate his
employment hereunder at any time for any reason, including but not limited to
Good Reason. For purposes of this Agreement, “Good Reason” shall mean that the
Executive has complied with the “Good Reason Process” (hereinafter defined)
following the occurrence of any of the following events: (i) the Company
materially reducing the scope of the Executive’s duties and responsibilities or
materially demoting or reducing the Executive’s authority; (ii) a material
change to the Executive’s primary place of employment with the Company, which
results in the Company changing the Executive’s primary place of employment to a
location that is more than 50 miles from the Executive’s primary place of
employment with the Company immediately prior to such change; or (iii) the
Company materially reducing the Executive’s base salary. “Good Reason Process”
shall mean that (i) the Executive reasonably determines in good faith that a
“Good Reason” condition has occurred; (ii) the Executive notifies the Company in
writing of the first occurrence of the Good Reason condition within 60 days of
the first occurrence of such condition; (iii) the Executive cooperates in good
faith with the Company’s efforts, for a period not less than 30 days following
such notice (the “Cure Period”), to remedy the condition; (iv) notwithstanding
such efforts, the Good Reason condition continues to exist; and (v) the
Executive terminates his employment within 180 days after the first occurrence
of the Good

3

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

Reason condition. If the Company cures the Good Reason condition during the Cure
Period, Good Reason shall be deemed not to have occurred.

     (f) Notice of Termination. Except for termination as specified in Section
3(a), any termination of the Executive’s employment by the Company or any such
termination by the Executive shall be communicated by written Notice of
Termination to the other party hereto, and shall be effective as of the
applicable Date of Termination specified in Section 3(g). For purposes of this
Agreement, a “Notice of Termination” shall mean a notice which shall indicate
the specific termination provision in this Agreement relied upon.

     (g) Date of Termination. “Date of Termination” shall mean: (i) if the
Executive’s employment is terminated by his death, the date of his death; (ii)
if the Executive’s employment is terminated on account of disability under
Section 3(b) or by the Company for Cause under Section 3(c), the date on which
Notice of Termination is given; (iii) if the Executive’s employment is
terminated by the Company under Section 3(d), 30 days after the date on which a
Notice of Termination is given; (iv) if the Executive’s employment is terminated
by the Executive under Section 3(e) without Good Reason, 30 days after the date
on which a Notice of Termination is given, and (v) if the Executive’s employment
is terminated by the Executive under Section 3(e) with Good Reason, the date on
which a Notice of Termination is given after the end of the Cure Period.
Notwithstanding the foregoing, in the event that the Executive gives a Notice of
Termination to the Company, the Company may unilaterally accelerate the Date of
Termination and such acceleration shall not result in a termination by the
Company for purposes of this Agreement.

4.      Compensation Upon Termination.     (a) Termination Generally. If the
Executive’s employment with the Company  

is terminated for any reason, the Company shall pay or provide to the Executive
(or to his authorized representative or estate) any earned but unpaid base
salary, incentive compensation earned but not yet paid, unpaid expense
reimbursements, accrued but unused vacation and any vested benefits the
Executive may have under any employee benefit plan of the Company (the “Accrued
Benefit”) on or before the time required by law but in no event more than 30
days after the Executive’s Date of Termination.

     (b) Termination by the Company Without Cause or by the Executive with Good
Reason. If the Executive’s employment is terminated by the Company without Cause
as provided in Section 3(d), or the Executive terminates his employment for Good
Reason as provided in Section 3(e), then the Company shall, through the Date of
Termination, pay the Executive his Accrued Benefit. In addition:

     (i) subject to the Executive signing a general release of claims in favor
of the Company and related persons and entities in a form and manner
satisfactory to the Company (the “Release”) within the 21-day period following
the Date of Termination and the expiration of the seven-day revocation period
for the Release, the Company shall pay the Executive an amount equal to two
times the Executive’s Base Salary (the “Severance Amount”). The Severance Amount
shall be paid in a lump sum on the first payroll date that occurs 30 days after
the Date of Termination; and

4

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

     (ii) the Executive may continue to participate in the Company’s group
health, dental and vision program for 24 months, with the cost of the premiums
for such benefits paid by the Company; provided, however, that the continuation
of health benefits under this Section shall reduce and count against the
Executive’s rights under the Consolidated Omnibus Budget Reconciliation Act of
1985, as amended (“COBRA”), and provided further that the cost of premiums for
such benefits attributable to the last six months of said 24 month period shall
be subject to the provisions of Section 6(b).

     5. Change of Control Payment. The provisions of this Section 5 set forth
certain terms of an agreement reached between the Executive and the Company
regarding the Executive’s rights and obligations upon the occurrence of a Change
of Control of the Company. These provisions are intended to assure and encourage
in advance the Executive’s continued attention and dedication to his assigned
duties and his objectivity during the pendency and after the occurrence of any
such event. These provisions shall apply in lieu of, and expressly supersede,
the provisions of Section 4(b) regarding severance pay and benefits upon a
termination of employment, if such termination of employment occurs within 24
months after the occurrence of the first event constituting a Change of Control.
These provisions shall terminate and be of no further force or effect beginning
24 months after the occurrence of a Change of Control.

     (a) Change of Control. If within 24 months after a Change of Control, the
Executive’s employment is terminated by the Company without Cause as provided in
Section 3(d) or the Executive terminates his employment for Good Reason as
provided in Section 3(e), then the Company shall, through the Date of
Termination, pay the Executive his Accrued Benefit on or before the time
required by law but in no event more than 30 days after the Executive’s Date of
Termination. In addition:

     (i) subject to the signing of the Release by the Executive within 30 days
after the Date of Termination and the expiration of the seven-day revocation
period for the Release, the Company shall pay the Executive a lump sum in cash
in an amount equal to two times the Executive’s current Base Salary (or the
Executive’s Base Salary in effect immediately prior to the Change of Control, if
higher). Such payment shall be paid on the first payroll date that occurs 30
days after the Date of Termination; and

     (ii) notwithstanding anything to the contrary in any applicable option
agreement or stock-based award agreement, all stock options and other
stock-based awards held by the Executive shall immediately vest and become fully
exercisable or issuable (without forfeiture restriction) as of the Date of
Termination; and

     (iii) the Executive may continue to participate in the Company’s group
health, dental and vision program for 24 months, with the cost of the premiums
for such benefits paid by the Company; provided, however, that the continuation
of health benefits under this Section shall reduce and count against the
Executive’s rights under COBRA, and provided further that the cost of premiums
for such benefits attributable to the last six months of said 24 month period
shall be subject to the provisions of Section 6(b).

5

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

     (b) Definitions. For purposes of this Section 5, the following terms shall
have the following meanings:

     A “Change of Control” shall be deemed to have occurred when any of the
following events takes place: (i) any Person is or becomes the beneficial owner
(as defined in Rule 13d-3 under the Securities and Exchange Act of 1934, as
amended), directly or indirectly, of 50 percent or more of the outstanding
common stock of the Company; (ii) a sale, merger or consolidation after which
securities possessing more than 50 percent of the total combined voting power of
the Company’s outstanding securities have been transferred to or acquired by a
Person or Persons different from the Persons who held such percentage of the
total combined voting power immediately prior to such transaction; or (iii) the
sale, transfer or other disposition of all or substantially all of the Company’s
assets to one or more Persons (other than a wholly owned subsidiary of the
Company or a parent company whose stock ownership after the transaction is the
same as the Company’s ownership before the transaction). For purposes of this
Change of Control definition, “Person” means an individual, a corporation, a
limited liability company, an association, a partnership, an estate, a trust and
any other entity or organization, other than the Company or any persons or
entities directly or indirectly controlling, controlled by or under common
control with the Company, where control may be by either management authority or
equity interest.

6.      Section 409A.     (a) Anything in this Agreement to the contrary
notwithstanding, if at the time  

of the Executive’s separation from service within the meaning of Section 409A of
the Internal Revenue Code of 1986, as amended (the “Code”), the Company
determines that the Executive is a “specified employee” within the meaning of
Section 409A(a)(2)(B)(i) of the Code, then to the extent any payment or benefit
that the Executive becomes entitled to under this Agreement on account of the
Executive’s separation from service would be considered deferred compensation
subject to the 20 percent additional tax imposed pursuant to Section 409A(a) of
the Code as a result of the application of Section 409A(a)(2)(B)(i) of the Code,
such payment shall not be payable and such benefit shall not be provided until
the date that is the earlier of (A) six months and one day after the Executive’s
separation from service, or (B) the Executive’s death. If any such delayed cash
payment is otherwise payable on an installment basis, the first payment shall
include a catch-up payment covering amounts that would otherwise have been paid
during the six-month period but for the application of this provision, and the
balance of the installments shall be payable in accordance with their original
schedule. Any such delayed cash payment shall earn interest at an annual rate
equal to the applicable federal short term rate published by the Internal
Revenue Service for the month in which the date of separation from service
occurs, from such date of separation from service until the payment.

     (b) All in-kind benefits provided and expenses eligible for reimbursement
under this Agreement shall be provided by the Company or incurred by the
Executive during the time periods set forth in this Agreement. All
reimbursements shall be paid as soon as administratively practicable, but in no
event shall any reimbursement be paid after the last day of the taxable year of
the Executive following the taxable year in which the expense was incurred. The
amount of in-kind benefits provided or reimbursable expenses incurred in one
taxable year

6

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

of the Executive shall not affect the in-kind benefits to be provided or the
expenses eligible for reimbursement in any other taxable year. Such right to
reimbursement or in-kind benefits is not subject to liquidation or exchange for
another benefit.

     (c) To the extent that any payment or benefit described in this Agreement
constitutes “non-qualified deferred compensation” under Section 409A of the
Code, and to the extent that such payment or benefit is payable upon the
Executive’s termination of employment, then such payments or benefits shall be
payable only upon the Executive’s “separation from service.” The determination
of whether and when a separation from service has occurred shall be made in
accordance with the presumptions set forth in Treasury Regulation Section
1.409A-1(h).

     (d) The parties intend that this Agreement will be administered in
accordance with Section 409A of the Code. To the extent that any provision of
this Agreement is ambiguous as to its compliance with Section 409A of the Code,
the provision shall be read in such a manner so that all payments hereunder
comply with Section 409A of the Code. The parties agree that this Agreement may
be amended, as reasonably requested by either party, and as may be necessary to
fully comply with Section 409A of the Code and all related rules and regulations
in order to preserve the payments and benefits provided hereunder without
additional cost to either party.

     (e) The Company makes no representation or warranty to the Executive or any
other person if any provisions of this Agreement are determined to constitute
deferred compensation subject to Section 409A of the Code but do not satisfy an
exemption from, or the conditions of, such Section.

     7. Noncompetition; Cooperation; Confidential Information; and Invention
Assignment.

     (a) Noncompetition and Nonsolicitation. During the Executive’s employment
with the Company and for 12 months thereafter, regardless of the reason for the
termination, the Executive (i) will not, directly or indirectly, whether as
owner, partner, shareholder, consultant, agent, employee, co-venturer or
otherwise, engage, participate, assist or invest in any Competing Business (as
hereinafter defined); (ii) will refrain from directly or indirectly employing,
attempting to employ, recruiting or otherwise soliciting, inducing or
influencing any person to leave employment with the Company (other than
terminations of employment of subordinate employees undertaken in the course of
the Executive’s employment with the Company); and (iii) will refrain from
soliciting or encouraging any customer or supplier to terminate or otherwise
modify adversely its business relationship with the Company. The Executive
understands that the restrictions set forth in this Section 7(a) are intended to
protect the Company’s interest in its confidential information and established
employee, customer and supplier relationships and goodwill, and agrees that such
restrictions are reasonable and appropriate for this purpose. For purposes of
this Agreement, the term “Competing Business” shall mean the business of
discovering, developing and/or commercializing: (i) pharmaceuticals that target
calcium and sodium ion channels, (ii) combination pharmaceuticals and
technologies that discover combination pharmaceuticals, (iii) modified release
formulations of long-acting opioids, or (iv) any other products that are
competitive with or similar to the products of the Company or

7

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

the products that the Company has under active development at the time of the
termination of Executive's employment. Notwithstanding the foregoing, the
Executive may own up to one percent (1%) of the outstanding stock of a publicly
held corporation which constitutes or is affiliated with a Competing Business,
and the Executive's Board of Directors memberships on the date of this Agreement
shall not be deemed to constitute a Competing Business.

     (b) Third-Party Agreements and Rights. The Executive hereby confirms that
the Executive is not bound by the terms of any agreement with any previous
employer or other party which restricts in any way the Executive’s employment by
the Company. The Executive represents to the Company that the Executive’s
execution of this Agreement, the Executive’s employment with the Company and the
performance of the Executive’s proposed duties for the Company will not violate
any obligations the Executive may have to any such previous employer or other
party. In the Executive’s work for the Company, the Executive will not disclose
or make use of any information in violation of any agreements with or rights of
any such previous employer or other party, and the Executive will not bring to
the premises of the Company any copies or other tangible embodiments of
non-public information belonging to or obtained from any such previous
employment or other party.

     (c) Litigation and Regulatory Cooperation. During and after the Executive’s
employment, the Executive shall cooperate fully with the Company in the defense
or prosecution of any claims or actions now in existence or which may be brought
in the future against or on behalf of the Company which relate to events or
occurrences that transpired while the Executive was employed by the Company. The
Executive’s full cooperation in connection with such claims or actions shall
include, but not be limited to, providing complete and truthful information and
testimony, being available to meet with counsel to prepare for discovery or
trial and to act as a witness on behalf of the Company at mutually convenient
times. During and after the Executive’s employment, the Executive also shall
cooperate fully with the Company in connection with any investigation or review
of any federal, state or local regulatory authority as any such investigation or
review relates to events or occurrences that transpired while the Executive was
employed by the Company. The Company shall reimburse the Executive for any
reasonable out-of-pocket expenses incurred in connection with the Executive’s
performance of obligations pursuant to this Section 7(c) and, if the Executive
is no longer employed by the Company, will additionally pay the Executive a per
diem (based upon the Executive’s Base Salary at the time of the Executive’s Date
of Termination) for any such cooperation other than the provision of testimony
in a deposition or trial setting.

     (d) Injunction. The Executive agrees that it would be difficult to measure
any damages caused to the Company which might result from any breach by the
Executive of the promises set forth in this Section 7, and that in any event
money damages would be an inadequate remedy for any such breach. The Executive
agrees that if the Executive breaches, or threatens to breach, any portion of
this Agreement, the Company shall be entitled, in addition to all other remedies
that it may have, to an injunction or other appropriate equitable relief to
restrain any such breach without showing or proving any actual damage to the
Company.

     (e) Confidential Information. The Executive agrees at all times during the
term of Executive’s employment and thereafter, to hold in strict confidence, and
not to use, except for the benefit of the Company, or to disclose to any person,
firm or corporation without

8

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

written authorization of an officer of the Company, any Confidential
Information. “Confidential Information” means any research conducted by the
Executive either alone or with others during the Executive’s employment by the
Company, and all results and data generated in connection therewith, and any
confidential or proprietary information, technical data, trade secrets or
knowhow of the Company, including, but not limited to, research and product
plans, products, services, customer lists and customers, markets, developments,
inventions, processes, formulas, technology, marketing, finances or other
business information disclosed to the Executive by the Company, either directly
or indirectly, in writing, orally or otherwise. The Executive recognizes that
the Company has received and in the future will receive from third parties
confidential or proprietary information of such third parties subject to a duty
on the Company’s part to maintain the confidentiality of such information and to
use such information only for certain limited purposes, and the Executive
understands that such information is also Confidential Information. The
Executive further understands that Confidential Information does not include any
of the foregoing information or items that has become publicly known and made
generally available

(f)      Inventions and Publication Reports.     (i) Inventions Retained and
Licensed. The Executive has attached  

hereto as Exhibit A a list describing all inventions, original works of
authorship, developments, improvements, and trade secrets of every nature and
kind, that were made by the Executive prior to his employment with the Company
(collectively referred to as “Prior Inventions”) or, if no such list is
attached, the Executive represents that there are no such Prior Inventions. If,
in the course of the Executive’s employment with the Company, the Executive
incorporates into a Company product, process or machine a Prior Invention owned
by the Executive or in which the Executive has an interest, the Company is
hereby granted and will have a non-exclusive, royalty free, irrevocable,
perpetual, worldwide license, with the right to grant sublicenses, to make, have
made, modify, use, sell, and otherwise exploit or utilize in any manner such
Prior Invention as part of or in connection with such product, process or
machine. The Executive further agrees that with respect to all Inventions or
other matters that may arise during the Executive’s employment that may result
in publishable material, with or without consideration, all such publications
rights shall belong exclusively to the Company. When and if such materials and
items are published by the Company, the Company agrees to note the Executive’s
involvement and development of such materials and items.

     (ii) Assignment of Inventions. The Executive agrees that he will promptly
make full written disclosure to the Company, and will hold in trust for the sole
right and benefit of the Company, and hereby assigns to the Company, or the
Company’s designee, the Executive’s full right, title, and interest in and to
any and all inventions, original works of authorship, developments, concepts,
improvements or trade secrets, whether or not patentable or registrable under
patent, copyright or similar laws, that the Executive may solely or jointly
make, develop, conceive or reduce to practice, or cause to be made, developed,
conceived or reduced to practice, during the period of time the Executive is in
the employ of the Company (collectively referred to as "Inventions”). The
Executive further acknowledges that all original works of authorship that are
made by the Executive (solely or jointly with others) within the scope of and
during the period

9

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

of his employment with the Company and that are protectable by copyright are
“works made for hire,” as that term is defined in the United States Copyright
Act.

     (iii) Maintenance of Records. The Executive agrees to keep and maintain
adequate and current written records of all Inventions made, developed,
conceived or reduced to practice by the Executive (solely or jointly with
others) during the term of the Executive’s employment with the Company. The
records will be in the form of notes, sketches, drawings, and any other format
that may be specified by the Company. The records will be available to and
remain the sole property of the Company at all times.

     (iv) Patent and Copyright Registrations. The Executive agrees to assist the
Company, or the Company’s designee, at the Company’s expense, in every way to
secure the Company’s rights in the Inventions and any copyrights, patents, mask
work rights or other intellectual property rights relating thereto in any and
all countries, including disclosing to the Company all pertinent information and
data with respect thereto, and executing all applications, specifications,
oaths, assignments and all other instruments that the Company shall deem
necessary in order to apply for and obtain such rights and in order to assign
and convey to the Company, the Company’s successors, assigns, and nominees the
sole and exclusive rights, title and interest in and to such Inventions, and any
copyrights, patents, mask work rights or other intellectual property rights
relating thereto. The Executive further agrees that his obligation to execute or
cause to be executed, when it is in his power to do so, any such instrument or
papers will continue after the termination of this Agreement. If the Executive
is unable because of his mental or physical incapacity or for any other reason
to secure his signature to apply for or to pursue any application for any United
States of America or foreign patents or copyright registrations covering
Inventions or original works of authorship assigned to the Company as above,
then the Executive hereby irrevocably designates and appoints the Company and
the Company’s duly authorized officers and agents as his agent and attorney in
fact, to act for and in his behalf and stead to execute and file any such
applications and to do all other lawfully permitted acts to further the
prosecution and issuance of letters patent or copyright registrations thereon
with the same legal force and effect as if executed by the Executive.

8. Consent to Jurisdiction. The parties hereby consent to the jurisdiction of
the

Superior Court of the Commonwealth of Massachusetts and the United States
District Court for the District of Massachusetts. Accordingly, with respect to
any such court action, the Executive (a) submits to the personal jurisdiction of
such courts; (b) consents to service of process; and (c) waives any other
requirement (whether imposed by statute, rule of court, or otherwise) with
respect to personal jurisdiction or service of process.

     9. Integration. This Agreement constitutes the entire agreement between the
parties with respect to the subject matter hereof and supersedes all prior
agreements between the parties concerning such subject matter.

10

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

     10. Withholding. All payments made by the Company to the Executive under
this Agreement shall be net of any tax or other amounts required to be withheld
by the Company under applicable law.

     11. Successor to the Executive. This Agreement shall inure to the benefit
of and be enforceable by the Executive’s personal representatives, executors,
administrators, heirs, distributees, devisees and legatees. In the event of the
Executive’s death after his termination of employment but prior to the
completion by the Company of all payments due him under this Agreement, the
Company shall continue such payments to the Executive’s beneficiary designated
in writing to the Company prior to his death (or to his estate, if the Executive
fails to make such designation).

     12. Enforceability. If any portion or provision of this Agreement
(including, without limitation, any portion or provision of any section of this
Agreement) shall to any extent be declared illegal or unenforceable by a court
of competent jurisdiction, then the remainder of this Agreement, or the
application of such portion or provision in circumstances other than those as to
which it is so declared illegal or unenforceable, shall not be affected thereby,
and each portion and provision of this Agreement shall be valid and enforceable
to the fullest extent permitted by law.

     13. Survival. The provisions of this Agreement shall survive the
termination of this Agreement and/or the termination of the Executive’s
employment to the extent necessary to effectuate the terms contained herein.

     14. Waiver. No waiver of any provision hereof shall be effective unless
made in writing and signed by the waiving party. The failure of any party to
require the performance of any term or obligation of this Agreement, or the
waiver by any party of any breach of this Agreement, shall not prevent any
subsequent enforcement of such term or obligation or be deemed a waiver of any
subsequent breach.

     15. Notices. Any notices, requests, demands and other communications
provided for by this Agreement shall be sufficient if in writing and delivered
in person or sent by a nationally recognized overnight courier service or by
registered or certified mail, postage prepaid, return receipt requested, to the
Executive at the last address the Executive has filed in writing with the
Company or, in the case of the Company, at its main offices in Cambridge,
Massachusetts, attention of the Board.

     16. Amendment. This Agreement may be amended or modified only by a written
instrument signed by the Executive and by a duly authorized representative of
the Company.

     17. Governing Law. This is a Massachusetts contract and shall be construed
under and be governed in all respects by the laws of the Commonwealth of
Massachusetts, without giving effect to the conflict of laws principles of such
Commonwealth. With respect to any disputes concerning federal law, such disputes
shall be determined in accordance with the law as it would be interpreted and
applied by the United States Court of Appeals for the First Circuit.

11

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

     18. Counterparts. This Agreement may be executed in any number of
counterparts, each of which when so executed and delivered shall be taken to be
an original; but such counterparts shall together constitute one and the same
document.

     19. Gender Neutral. Wherever used herein, a pronoun in the masculine gender
shall be considered as including the feminine gender unless the context clearly
indicates otherwise.

12

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

     IN WITNESS WHEREOF, the parties have executed this Agreement effective on
the date and year first above written.

COMBINATORX, INCORPORATED

By: /s/ Jason F. Cole
Title: SVP and General Counsel

EXECUTIVE

/s/ Mark H. N. Corrigan
Mark H.N. Corrigan, M.D.

[Signature Page to Employment Agreement]

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