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 pursuant 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 Annual Report on Form 10-K of the Company for the
      period ended December 31, 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: March 31, 2005

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

                                      /s/ KENNETH W. JOHNSON
                                          Kenneth W. Johnson
                                          Chief Financial and Accounting Officer

The foregoing certification is being furnished solely to accompany the Report
pursuant to 18 U.S.C. ss. 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.