EXHIBIT 99.1


I, Merrill A. Miller, Jr., Chairman, President and Chief Executive Officer of
National-Oilwell, Inc., certify, pursuant to Section 906 of the Sarbanes-Oxley
Act of 2002, that:

     (1) the Quarterly Report on Form 10-Q for the quarterly period ended March
         31, 2003 (the "Periodic Report') which this statement accompanies fully
         complies with the requirements of Section 13(a) of the Securities
         Exchange Act of 1934 (15 U.S.C. 78m) and


     (2) information contained in the Periodic Report fairly presents, in all
         material respects, the financial condition and results of operations of
         National-Oilwell, Inc.


Dated: May 15, 2003

                                 /s/ Merrill A. Miller, Jr.
                                 --------------------------
                                 Merrill A. Miller, Jr.
                                 Chairman, President and Chief Executive Officer