Exhibit 99.1

                    CERTIFICATION OF CHIEF EXECUTIVE OFFICER
                                   PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

I, Anthony J. Ley, certify, pursuant to 18 U.S.C. Section 1350, as adopted
pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the Quarterly
Report of Harmonic Inc. on Form 10-Q for the fiscal quarter ended June 27, 2003
fully complies with the requirements of Section 13(a) or 15(d) of the Securities
Exchange Act of 1934 and that information contained in such Quarterly Report on
Form 10-Q fairly presents in all material respects the financial condition and
results of operations of Harmonic Inc.

By: /s/ Anthony J. Ley
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Name:  Anthony J. Ley
Title: Chairman, President and Chief Executive Officer