SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

                                FORM 10-K / A-1


|X|  ANNUAL REPORT  PURSUANT TO SECTION 13 OR 15(d) OF THE  SECURITIES  EXCHANGE
     ACT OF 1934 - For the fiscal year ended December 31, 1998

                                      OR

|_|  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934

                         Commission file number 1-640

                             NL INDUSTRIES, INC.
--------------------------------------------------------------------------------
            (Exact name of registrant as specified in its charter)

          New Jersey                                       13-5267260
-------------------------------                       -------------------
(State or other jurisdiction of                         (IRS Employer
 incorporation or organization)                       Identification No.)

16825 Northchase Drive, Suite 1200, Houston, Texas        77060-2544
--------------------------------------------------        ----------
   (Address of principal executive offices)               (Zip Code)

Registrant's telephone number, including area code:      (281) 423-3300

Securities registered pursuant to Section 12(b) of the Act:

                                             Name of each exchange on
     Title of each class                         which registered
------------------------------               ------------------------
Common stock ($.125 par value)               New York Stock Exchange
                                             Pacific Exchange

Securities registered pursuant to Section 12(g) of the Act:  None.

Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the  preceding 12 months,  and (2) has been subject to such filing  requirements
for the past 90 days.     Yes X              No

Indicate by check mark if disclosure of delinquent  filers  pursuant to Item 405
of Regulation  S-K is not contained  herein,  and will not be contained,  to the
best of registrant's  knowledge,  in definitive proxy or information  statements
incorporated by reference in Part III of this Form 10-K or any amendment to this
Form 10-K. |_|

As of March 22, 1999,  51,826,139 shares of common stock were  outstanding.  The
aggregate  market  value  of the  11,475,208  shares  of  voting  stock  held by
nonaffiliates as of such date approximated $107 million.

                     Documents incorporated by reference:

The  information  required by Part III is  incorporated  by  reference  from the
Registrant's  definitive  proxy  statement to be filed with the  Securities  and
Exchange Commission pursuant to Regulation 14A not later than 120 days after the
end of the fiscal year covered by this report.


<PAGE>



The  undersigned   Registrant  hereby  amends  the  following  items,  financial
statements, exhibits or other portions of its Annual Report on Form 10-K for the
year  ended  December  31,  1998 as set forth  below  and in the pages  attached
hereto:

Item 14. EXHIBITS, FINANCIAL STATEMENT SCHEDULES,
         AND REPORTS ON FORM 8-K.

         Exhibit No. 99.1, Annual Report of NL Industries, Inc. Retirement
         Savings Plan on Form 11-K for the year ended December 31, 1998 (filed
         as an amendment to the Registrant's Annual Report on Form 10-K for the
         year ended December 31, 1998).




<PAGE>



      Pursuant to the  requirements of the Securities  Exchange Act of 1934, the
Registrant  has duly  caused  this  amendment  to be signed on its behalf by the
undersigned, thereunto duly authorized.



                                                     NL INDUSTRIES, INC.
                                                ------------------------------
                                                         (Registrant)



Dated:  June 4, 1999                      By:   /s/ Robert D. Hardy
                                                ------------------------------
                                                Robert D. Hardy
                                                Vice President and Controller