EXHIBIT 32.1

CERTIFICATION OF CHIEF EXECUTIVE OFFICER AND CHIEF FINANCIAL OFFICER

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 Annual Report on Form 10-K of Riverbed Technology, Inc. for the year ended December 31, 2008 as filed with the Securities and Exchange Commission on the date hereof, Jerry M. Kennelly, as President, and Chief Executive Officer, and Randy S. Gottfried, as Chief Financial Officer, each hereby certifies, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

1. The Annual Report on Form 10-K 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 Annual Report on Form 10-K fairly presents, in all material respects, the financial condition and results of operations of Riverbed Technology, Inc.

Date: February 23, 2009	/S/ JERRY M. KENNELLY
	Jerry M. Kennelly
	President and Chief Executive Officer
	(Principal Executive Officer)
Date: February 23, 2009	/S/ RANDY S. GOTTFRIED
	Randy S. Gottfried
	Chief Financial Officer
	(Principal Financial and Accounting Officer)

A signed original of this written statement required by Section 906 of the Sarbanes-Oxley Act of 2002 has been provided to Riverbed Technology, Inc. and will be retained by Riverbed Technology, Inc. and furnished to the Securities and Exchange Commission or its staff upon request.