Exhibit 32.1

                                  Harmonic Inc.
                  Certification of Principal Executive Officer
            Pursuant to 18 U.S.C. Section 1350 as Adopted Pursuant to
                  Section 906 of the Sarbanes-Oxley Act of 2002

As of the date hereof, I, Anthony J. Ley, Chairman, President and Chief
Executive Officer of Harmonic Inc. (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 the quarterly report of the Company on Form 10-Q for the
fiscal quarter ended October 1, 2004, as filed with the Securities and Exchange
Commission (the "Report"), fully complies with the requirements of Section 13(a)
or 15(d) of the Securities Act of 1934 and that information contained in the
Report fairly presents, in all material respects, the financial condition and
results of operations of the Company. This written statement is being furnished
to the Securities and Exchange Commission as an exhibit accompanying such Report
and shall not be deemed filed pursuant to the Securities Exchange Act of 1934.

Date:  November 5, 2004

                                /s/ Anthony J. Ley
                                ------------------------------------------------
                                Anthony J. Ley
                                Chairman, President and Chief Executive Officer
                                (Principal Executive Officer)