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 Quarterly Report on Form 10-Q, the undersigned hereby certify that this Quarterly Report on Form 10-Q 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 Quarterly Report on Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of the Company. Dated: March 2, 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 Quarterly Report on Form 10-Q, the undersigned hereby certify that this Quarterly Report on Form 10-Q 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 Quarterly Report on Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of the Company. Dated: March 2, 2004 By: /s/ Steven W. Tholen ------------------------------------- Steven W. Tholen Senior Vice President, Chief Financial Officer and Treasurer