EXHIBIT 99.1

                            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 Quarterly Report of Gartner, Inc. (the "Company")
on Form 10-Q for the three month period ended March 31, 2003, as filed with the
Securities and Exchange Commission on the date hereof (the "Report"), I, Michael
D. Fleisher, Chief Executive Officer of the Company, certify, pursuant to 18
U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley
AcT of 2002, that, to my knowledge:

            (1) The Report fully complies with the requirements of Section 13(a)
            or 15(d) of the Securities Exchange Act of 1934; and

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

/s/ Michael D. Fleisher
- ------------------------------------
Chief Executive Officer

Date:  May 14, 2003


A signed original of this written statement required by Section 906 has been
provided to Gartner, Inc. and will be retained by Gartner, Inc. and furnished to
the Securities and Exchange Commission or its staff upon request.