EXHIBIT 31.1

                                 CERTIFICATION




I, Harold C. Simmons the Chairman of the Board and Chief Executive Officer of NL
Industries, Inc., certify that:

1)   I have reviewed this annual report on Form 10-K/A  (Amendment  No. 1) of NL
     Industries, Inc.; and
2)   Based on my  knowledge,  this  annual  report  does not  contain any untrue
     statement of a material fact or omit to state a material fact  necessary to
     make the statements  made, in light of the  circumstances  under which such
     statements  were made, not misleading with respect to the period covered by
     this annual report.


Date: June 29, 2004

/s/ Harold C. Simmons
-----------------------------
Chairman of the Board and
Chief Executive Officer