Exhibit
32.1
CERTIFICATION
PURSUANT
TO 18 U.S.C. SECTION 1350,
AS
ADOPTED PURSUANT TO SECTION 906
OF
THE
SARBANES-OXLEY ACT OF 2002
In
connection with the accompanying Annual Report on Form 10-K of The GSI Group,
Inc., a Delaware corporation (the "Company"), for the year ended December 31,
2006, as filed with the Securities and Exchange Commission on the date hereof
(the "Report"), and pursuant to 18 U.S.C. Section 1350, as adopted pursuant
to
Section 906 of the Sarbanes-Oxley Act of 2002, William J. Branch, as Chief
Executive Officer of the Company, and John Henderson as Chief Financial Officer
of the Company, hereby certify that the Report fully complies with the
requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934;
and
The
information contained in the Report fairly presents, in all material respects,
the financial condition and results of operations of the Company.
Dated:
March 27, 2007
/s/
WILLIAM J. BRANCH
William
J. Branch
Chief
Executive Officer and Chairman of the Board
/s/
JOHN HENDERSON
John
Henderson
Chief
Financial Officer
This
certification shall not be deemed "filed" by the Company for purposes of Section
18 of the Securities Exchange Act of 1934. In addition, this certification
shall
not be deemed to be incorporated by reference into any filing under the
Securities Act of 1933 or the Securities Exchange Act of 1934.
A
signed
original of this written statement required by Section 906 of the Sarbanes-Oxley
Act of 2002 has been provided to the Company and will be retained by the Company
and furnished to the Securities and Exchange Commission or its staff upon
request.