EXHIBIT 32.1 CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350, AS ADOPTED BY SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002 Each of the undersigned hereby certifies, pursuant to 18 U.S.C. Section 1350, in his capacity as an officer of Diamond Offshore Drilling, Inc. (the "Company"), that, to his knowledge: (1) the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2005, as filed with the U.S. Securities and Exchange Commission on the date hereof (the "Report"), fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and (2) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company. Dated: July 29, 2005 \s\ James S. Tisch - -------------------------------------- James S. Tisch Chief Executive Officer of the Company \s\ Gary T. Krenek - -------------------------------------- Gary T. Krenek Chief Financial Officer of the Company