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Exhibit 99.1

Certification of CEO and CFO 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 on Form 10-Q of Chicago Mercantile Exchange Holdings Inc. (the "Company") for the quarterly period ended September 30, 2002 as filed with the Securities and Exchange Commission on the date hereof (the "Report"), James J. McNulty, as Chief Executive Officer of the Company, and David G. Gomach, as Chief Financial Officer of the Company, each hereby certifies, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 of the Sarbanes-Oxley Act of 2002, that, to the best of his 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/  JAMES J. MCNULTY
Name:	James J. McNulty
Title:	Chief Executive Officer
Date:	October 28, 2002
	/s/  DAVID G. GOMACH
Name:	David G. Gomach
Title:	Chief Financial Officer
Date:	October 28, 2002

        This certification accompanies the Report pursuant to § 906 of the Sarbanes-Oxley Act of 2002 and shall not, except to the extent required by the Sarbanes-Oxley Act of 2002, be deemed filed by the Company for purposes of §18 of the Securities Exchange Act of 1934, as amended.

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Exhibit 99.1