Supplemental Indenture

On December 31, 2008, O'Reilly Automotive, Inc. entered into the Fourth Supplemental Indenture (the "Fourth Supplemental Indenture") with respect to the $100 million principal amount of 6¾% Exchangeable Senior Notes due 2025, originally issued by CSK Auto Corporation ("CSK") pursuant to an Indenture, dated as of December 19, 2005, as amended and supplemented by the First Supplemental Indenture dated as of December 30, 2005, the Second Supplemental Indenture dated as of July 27, 2006, and the Third Supplemental Indenture dated as of July 11, 2008, by and between CSK, CSK Auto, Inc. and The Bank of New York Mellon Trust Company, N.A., as trustee, in order to correct the definition of Exchange Rate. The Fourth Supplemental Indenture is effective as of July 11, 2008.

The foregoing summary of the material terms of the Fourth Supplemental Indenture is not complete and is qualified in its entirety by the complete terms and conditions of the Fourth Supplemental Indenture, which is filed as Exhibit 10.1 to this Current Report on Form 8-K and is incorporated herein by reference.

(d) Exhibits

Exhibit No.                                Description

10.1          Fourth Supplemental Indenture, dated as of December 31, 2008, among
              O'Reilly Automotive, Inc., CSK Auto Corporation, CSK Auto, Inc.,
              CSKAUTO.COM, Inc. and The Bank of New York Trust Company, N.A., as
              Trustee.