POWER OF ATTORNEY

Know all by these presents, that the undersigned hereby constitutes
and appoints each of Thomas S. Grilk  and Lynda M. Avallone, signing
singly, 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 of Brooks Automation, Inc. (the
"Company"), Forms 3, 4, and 5 in accordance with Section 16(a) of the
Securities Exchange Act of 1934 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, complete and execute any amendment or amendments thereto, 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 such 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 that such attorney-in-fact, or such attorney-in-fact's substitute or
substitutes, 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 the foregoing attorneys-in-fact, in serving in such
capacity at the request of the undersigned, are not assuming, nor is the
Company assuming, any of the undersigned's responsibilities to comply with
Section 16 of the Securities Exchange Act of 1934.
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 the foregoing attorneys-in-fact.
IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney
to be executed as of this 26th day of  February, 2003.
/s/Jeffrey A. Cassis
Signature

Jeffrey A. Cassis
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