POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby
constitutes and appoints each of Alexis Borisy, Robert Forrester
and Geoffrey Davis, signing singly, as the undersigned's true and
lawful attorney-in-fact to:

(1)	execute for and on behalf of the undersigned, in the
undersigned's capacity as an officer and/or director, or investor
of COMBINATORX, INCORPORATED (the "Company"), Forms 3, 4 and 5 in
accordance with Section 16(a) of the Securities Exchange Act of
1934, as amended (the "Act"), and the rules thereunder;

(2)	do and perform any and all acts for and on behalf of the
undersigned which may be necessary or desirable to complete and
execute any such Form 3, 4 or 5 and timely file such form with
the United States Securities and Exchange Commission and any
stock exchange or similar authority; and

(3)	take any other action of any type whatsoever in connection
with the foregoing which, in the opinion of such attorney-in-
fact, may be of benefit to, in the best interest of, or legally
required by, the undersigned, it being understood that the
documents executed by such attorney-in-fact on behalf of the
undersigned pursuant to this Power of Attorney shall be in such
form and shall contain such terms and conditions as such
attorney-in-fact may approve in such attorney-in-fact's
discretion.

The undersigned hereby grants to each of the attorney-in-fact
full power and authority to do and perform any and every act and
thing whatsoever requisite, necessary or proper to be done in the
exercise of any of the rights and powers herein granted, as fully
to all intents and purposes as the undersigned might or could do
if personally present, with full power of substitution or
revocation, hereby ratifying and confirming all the acts such
attorney-in-fact shall lawfully do or cause to be done by virtue
of this power of attorney and the rights and powers herein
granted.  The undersigned acknowledges that each of the foregoing
attorneys-in-fact, in serving in such capacity at the request of
the undersigned, is not assuming any of the undersigned's
responsibilities to comply with Section 16 of the Act.

This Power of Attorney shall remain in full force and effect
until the undersigned is no longer required to file Forms 3, 4
and 5 with respect to the undersigned's holdings of and
transactions in securities issued by the Company, unless earlier
revoked by the undersigned in a signed writing delivered to each
of the foregoing attorneys-in-fact.

IN WITNESS WHEREOF, the undersigned has caused this Power of
Attorney to be executed as of this 24th day of February, 2005.

By: /s/ Richard Pops
Name: Richard Pops