Exhibit 32.1

O’REILLY AUTOMOTIVE, INC. AND SUBSIDIARIES

CEO Certification

O’REILLY AUTOMOTIVE, INC.

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 report of O’Reilly Automotive, Inc. (the “Company”) on Form 10-Q for the period ended March 31, 2008, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Greg Henslee, 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:

(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 result of operations of the Company.

/s/ Greg Henslee

Greg Henslee

Chief Executive Officer

(Principal Executive Officer)

May 9, 2008

The foregoing certification is being furnished as an exhibit to the Report pursuant to Item 601(b)(32) of Regulation S-K and Section 1350 of Title 18 of the United States Code and, accordingly, is not being filed with the Securities and Exchange Commission (the “Commission”) as part of the Report and is not to be incorporated by reference into any filing of the Company with the Commission, whether made before or after the date of the Report, irrespective of any general incorporation language contained in such filing.