EXHIBIT 32.1

                 Certificate Pursuant to 18 U.S.C. Section 1350,
      as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002

Pursuant to 18 U.S.C. Section 1350, as adopted to Section 906 of the
Sarbanes-Oxley Act of 2002, the undersigned officers of Cray Inc. (the
"Company") hereby certify, to such officers' knowledge, that:

      (i) the accompanying Quarterly Report on Form 10-Q of the Company for the
      period ended September 30, 2004 (the "Report") fully complies with the
      requirements of Section 13(a) or Section 15(d), as applicable, of the
      Securities Exchange Act of 1934, as amended; and

      (ii) the information contained in the Report fairly presents, in all
      material respects, the financial condition and results of operations of
      the Company.

      Dated: November 9, 2004

                               /s/ JAMES E. ROTTSOLK
                                   James E. Rottsolk
                                   Chief Executive Officer and President

                               /s/ SCOTT J. POTERACKI
                                   Scott J. Poteracki
                                   Senior Vice President and Chief Financial and
                                   Accounting Officer

      The foregoing certification is being furnished solely to accompany the
      Report pursuant to 18 U.S.C. Section 1350, and is not being filed for
      purposes of Section 18 of the Securities Exchange Act of 1934, as amended,
      and is not to be incorporated by reference into any filing of the Company,
      whether made before or after the date hereof, regardless of any general
      incorporation language in such filing.