Exhibit 99

                    CERTIFICATION OF CHIEF EXECUTIVE OFFICER
                      PURSUANT TO 18 U. S. C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


In connection with the Quarterly Report of Rowan Companies, Inc. (the "Company")
on Form 10-Q for the period ended March 31, 2003, as filed with the Securities
and Exchange Commission on the date hereof (the "Report"), I, D. F. McNease,
Chief Executive Officer of 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, to the best of my knowledge:

      (1)   The Report fully complies with the requirements of Section 13(a) or
            15(d) of the Securities Exchange Act of 1934; and

      (2)   The information contained in the Report fairly presents, in all
            material respects, the financial condition and results of operations
            of the Company for the periods presented.


Date:   May 15, 2003                      /s/ D. F. McNease
                                          -------------------------------------
                                          D. F. McNease
                                          President and Chief Executive Officer



                    CERTIFICATION OF CHIEF FINANCIAL OFFICER
                      PURSUANT TO 18 U. S. C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


In connection with the Quarterly Report of Rowan Companies, Inc. (the "Company")
on Form 10-Q for the period ended March 31, 2003, as filed with the Securities
and Exchange Commission on the date hereof (the "Report"), I, E. E. Thiele,
Chief Financial Officer of 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, to the best of my knowledge:

      (1)   The Report fully complies with the requirements of Section 13(a) or
            15(d) of the Securities Exchange Act of 1934; and

      (2)   The information contained in the Report fairly presents, in all
            material respects, the financial condition and results of operations
            of the Company for the periods presented.


Date:   May 15, 2003                      /s/ E. E. THIELE
                                          -------------------------------------
                                          E. E. Thiele
                                          Senior Vice President - Finance,
                                          Administration and Treasurer
                                          (Chief Financial Officer)