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 annual report of the Company on Form 10-K for the fiscal
year ended December 31, 2003, 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 Exchange 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:  March 8, 2004

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