EXHIBIT 32.1 ACCOMPANYING CERTIFICATE PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 Furnished Pursuant to the Securities Exchange Act of 1934 The undersigned Chief Executive Officer of Harvest Natural Resources, Inc. (the "Company") does hereby certify as follows: Solely for the purpose of meeting the apparent requirements of Section 906 of the Sarbanes-Oxley Act of 2002, and solely to the extent this certification may be applicable to this Annual Report on Form 10-K, the undersigned hereby certifies that this 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 the information contained in this Annual Report on Form 10-K fairly presents, in all material respects, the financial condition and results of operations of the Company for the period covered by the report. Dated: March 9, 2004 By: /s/ Peter J. Hill --------------------------------------- Peter J. Hill President and Chief Executive Officer ACCOMPANYING CERTIFICATE PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 Furnished Pursuant to the Securities Exchange Act of 1934 The undersigned Chief Financial Officer of Harvest Natural Resources, Inc. (the "Company") does hereby certify as follows: Solely for the purpose of meeting the apparent requirements of Section 906 of the Sarbanes-Oxley Act of 2002, and solely to the extent this certification may be applicable to this Annual Report on Form 10-K, the undersigned hereby certifies that this 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 the information contained in this Annual Report on Form 10-K fairly presents, in all material respects, the financial condition and results of operations of the Company for the period covered by the report. Dated: March 9, 2004 By: /s/ Steven W. Tholen --------------------------------------- Steven W. Tholen Senior Vice President - Finance, Chief Financial Officer and Treasurer