SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                    Form 11-K


            Annual Report pursuant to Section 15(d) of the Securities
       Exchange Act of 1934 - for the fiscal year ended December 31, 2005


                          Commission file number 1-640


A.   Full title of the plan and the address of the plan if  different  from that
     of the issuer named below:


                               NL INDUSTRIES, INC.
                             RETIREMENT SAVINGS PLAN


B.   Name of issuer of the securities  held pursuant to the plan and the address
     of its principal executive office:


                               NL INDUSTRIES, INC.
                          5430 LBJ Freeway, Suite 1700
                                Dallas, TX 75240



                                    SIGNATURE




     Pursuant to the  requirements  of the Securities  Exchange Act of 1934, the
Administrator has duly caused this Annual Report to be signed by the undersigned
thereunto duly authorized.


                                                  NL INDUSTRIES, INC.
                                                  RETIREMENT SAVINGS PLAN

                                            By: NL INDUSTRIES, INC.
                                                  PENSION AND EMPLOYEE
                                                  BENEFITS COMMITTEE,
                                                  Administrator of
                                                  NL Industries, Inc.
                                                  Retirement Savings Plan

                                            By: /s/ Gregory M. Swalwell
                                                -----------------------------

                                                  Gregory M. Swalwell,
                                                  Chairman, Pension and
                                                  Employee Benefits Committee

June 28, 2006












                               NL INDUSTRIES, INC.
                             RETIREMENT SAVINGS PLAN

                              FINANCIAL STATEMENTS
                     WITH REPORTS OF INDEPENDENT REGISTERED
                             PUBLIC ACCOUNTING FIRMS

                                December 31, 2005








                   NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN

                          Index of Financial Statements



                                                                           Page

Reports of Independent Registered Public Accounting Firms

   Sutton Frost Cary LLP                                                    2

   PricewaterhouseCoopers LLP                                               3

Financial Statements

   Statements of Net Assets Available for Benefits -
    December 31, 2004 and 2005                                              4

   Statement of Changes in Net Assets Available for Benefits -
    Year ended December 31, 2005                                            5

   Notes to Financial Statements                                            6

Exhibit A
   Consent of Independent Registered Public Accounting Firm
   (Sutton Frost Cary LLP)

Exhibit B
   Consent of Independent Registered Public Accounting Firm
   (PricewaterhouseCoopers LLP)




             REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM



To the Participants and Administrator of NL Industries,  Inc. Retirement Savings
Plan:


     In our opinion,  the  accompanying  statement of net assets  available  for
benefits  and the  related  statement  of changes in net  assets  available  for
benefits present fairly, in all material respects,  the net assets available for
benefits of NL Industries, Inc. Retirement Savings Plan (the "Plan") at December
31, 2005, and the changes in net assets available for benefits for the year then
ended in conformity with accounting  principles generally accepted in the United
States of America.  These  financial  statements are the  responsibility  of the
Plan's  management.  Our  responsibility  is to  express  an  opinion  on  these
financial  statements  based  on our  audit.  We  conducted  our  audit of these
statements in accordance  with the  standards of the Public  Company  Accounting
Oversight  Board  (United  States).  Those  standards  require  that we plan and
perform the audit to obtain  reasonable  assurance  about  whether the financial
statements are free of material misstatement. An audit includes consideration of
internal  control  over  financial  reporting  as a basis  for  designing  audit
procedures that are appropriate in the circumstances, but not for the purpose of
expressing an opinion on the  effectiveness  of the Plan's internal control over
financial  reporting.  Accordingly,  we express no such  opinion.  An audit also
includes  examining,  on a test  basis,  evidence  supporting  the  amounts  and
disclosures in the financial  statements,  assessing the  accounting  principles
used and  significant  estimates made by management,  and evaluating the overall
financial  statement  presentation.   We  believe  that  our  audit  provides  a
reasonable basis for our opinion.

     As further  described in Note 2,  effective  December  31,  2005,  the Plan
merged into The Employee 401(k) Retirement Plan.






                                                  Sutton Frost Cary LLP



Arlington, Texas
June 2, 2006



             REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM



To the Participants and Administrator of NL Industries,  Inc. Retirement Savings
Plan:

     In our opinion,  the  accompanying  statement of net assets  available  for
benefits presents fairly, in all material respects, the net assets available for
benefits of NL Industries, Inc. Retirement Savings Plan (the "Plan") at December
31, 2004 in conformity  with  accounting  principles  generally  accepted in the
United  States of America.  This  financial  statement is the
responsibility  of the Plan's  management.  Our  responsibility is to express an
opinion on this financial  statement  based on our audit. We conducted our audit
of this  statement  in  accordance  with the  standards  of the  Public  Company
Accounting Oversight Board  (United  States). Those standards
require that we plan and perform the audit to obtain reasonable  assurance about
whether the financial  statements  are free of material  misstatement.  An audit
includes  examining,  on a test  basis,  evidence  supporting  the  amounts  and
disclosures in the financial statement, assessing the accounting principles used
and  significant  estimates  made by  management,  and  evaluating  the  overall
financial  statement  presentation.   We  believe  that  our  audit  provides  a
reasonable basis for our opinion.




PricewaterhouseCoopers LLP


Dallas, Texas
June 28, 2005







                   NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN

                 STATEMENTS OF NET ASSETS AVAILABLE FOR BENEFITS

                           December 31, 2004 and 2005


<TABLE>

                                                                  2004                2005
                                                                  ----                ----

 Assets:
<S>                                                           <C>                 <C>
   Investments at fair value                                  $24,880,674         $      -
   Loans to participants                                           51,789                -
   Cash                                                               656                -
                                                              -----------         -----------

                                                               24,933,119                -

   Employer contributions receivable                              413,461                -
   Interest receivable                                             12,043                -
                                                              -----------         -----------

     Net assets available for benefits                        $25,358,623         $      -
                                                              ===========         ===========
</TABLE>






                 See accompanying notes to financial statements.






                   NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN

            STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS

                          Year ended December 31, 2005



<TABLE>

 Additions:
   Investment income:
<S>                                                                             <C>
     Net appreciation in the fair value of investments                          $    87,005
     Dividends                                                                      592,492
     Interest                                                                       351,780
                                                                                -----------

       Total investment income                                                    1,031,277
                                                                                -----------

   Contributions:
     Participants                                                                   563,751
     Employer                                                                       350,138
                                                                                -----------

       Total contributions                                                          913,889
                                                                                -----------

         Total additions                                                          1,945,166

 Deductions - benefits to participants                                            7,031,751
                                                                                -----------

 Net decrease in net assets available for benefits prior to merger               (5,086,585)

 Merger to The Employee 401(k) Retirement Plan                                  (20,272,038)

 Net assets available for benefits:
   Beginning of year                                                             25,358,623
                                                                                -----------

   End of year                                                                  $      -
                                                                                ===========
</TABLE>


                 See accompanying notes to financial statements.


                   NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN

                          NOTES TO FINANCIAL STATEMENTS


Note 1 - Description of Plan and summary of significant accounting policies:

     General.  The financial  statements of the NL Industries,  Inc.  Retirement
Savings Plan (the  "Plan")  have been  prepared in  accordance  with  accounting
principles generally accepted in the United States of America
("GAAP").   The  following   description  of  the  Plan  provides  only  general
information. Participants should refer to the Plan agreement for a more complete
description  of the Plan's  provisions.  The Plan was merged  into The  Employee
401(k) Retirement Plan ("Retirement Plan") on December 31, 2005. See Note 2.

     The Plan is a defined contribution plan, which covers eligible salaried and
hourly  U.S.  employees  of  NL  Industries,   Inc.  and  certain  of  its  U.S.
subsidiaries and affiliates  (collectively,  the "Employer"),  including EWI Re,
Inc. ("EWI") and Kronos Worldwide,  Inc (NYSE:  KRO).  Employees are eligible to
participate in the Plan as of the first entry date, as defined,  concurrent with
or next following the completion of six months of eligible service.  The Plan is
subject to the  provisions  of the Employee  Retirement  Income  Security Act of
1974, as amended ("ERISA").

     NL Industries,  Inc. (NYSE: NL) is a subsidiary of Valhi, Inc. (NYSE: VHI).
At December  31,  2005,  (i) Valhi held  approximately  83% of NL's  outstanding
common  stock  and  (ii)  Contran   Corporation   and  its   subsidiaries   held
approximately  92% of Valhi's  outstanding  common stock.  Substantially  all of
Contran's outstanding voting stock is held by trusts established for the benefit
of certain children and grandchildren of Harold C. Simmons, of which Mr. Simmons
is sole trustee,  or is held by Mr. Simmons or persons or other entities related
to Mr. Simmons.  Consequently, Mr. Simmons may be deemed to control each of such
companies and the Plan.

     At December 31, 2005, NL held  approximately 36% of the outstanding  common
stock of Kronos, and Valhi held an additional 57% of Kronos'  outstanding common
stock. Prior to July 2004, Kronos was a majority-owned subsidiary of NL.

     Basis of  accounting.  The  financial  statements  of the Plan are prepared
under the accrual method of accounting.

     Contributions.  The  majority  of  the  Employer's  U.S.
employees are eligible to  voluntarily  participate in the Plan after six months
of employment. Active participants may make "basic contributions" (as defined by
the  Plan)  of  between  1%  and  8%  of  their  eligible  compensation.   Basic
contributions   may  consist  of  a   combination   of  pre-tax  and   after-tax
contributions. Generally, pre-tax contributions are excluded from the employee's
taxable income until they are distributed.  Eligible employees that have elected
to make the maximum basic contribution of 8% may also make supplemental  pre-tax
or  after-tax  contributions  of  between  1% and up to  92% of  their  eligible
compensation.  Pursuant  to the  Internal  Revenue  Code (the  "Code"),  pre-tax
contributions are limited to $14,000 in 2005 and total participant contributions
(pre-tax and  after-tax)  and employer  contributions  are limited to $42,000 in
2005.  Eligible  employees age 50 or over, by the end of the Plan year, may make
an additional $4,000 pre-tax catch-up contribution.

     Highly  compensated  participants  may be  required to adjust the amount of
their   contributions   in  order  to  permit  the  Plan  to   satisfy   certain
nondiscrimination requirements of the Code.

     Contributions  from  eligible  employees  are  recorded  in the  period the
employer   makes   payroll   deductions   from   Plan   participants.   Employer
contributions,  if any,  are accrued by the end of each year and are received in
the subsequent year.

     Employer   contributions  include  (i)  a  match  equal  to  a  portion  of
participants'  contributions,  (ii) an annual  contribution  of 4% of employees'
eligible earnings and (iii) with respect to certain participants, a contribution
related to a decision to freeze the U.S.  defined benefit plans of NL and Kronos
in 1996. The Company's level of matching  contributions  is determined  annually
and is based upon the  attainment  of certain  operating  income  target  levels
approved by the Management  Development and Compensation  Committee of the Board
of Directors of Kronos (the "MD&C Committee"). The Company match applies only to
eligible participants' basic contributions. The level of match for 2005 was 50%.
Employees  who are  eligible  to  participate  in the  Plan  receive  an  annual
contribution to their investment accounts of 4% of their eligible  compensation,
subject  to  Internal   Revenue   Service   ("IRS")   limitations   on  eligible
compensation,  which  for 2005 was  $210,000.  The  Company  makes  this  annual
contribution  for each  eligible  employee  regardless  of whether the  employee
elects to otherwise participate in the Plan. While EWI employees are eligible to
participate in the Plan with the same  eligibility  requirements  and vesting as
described herein, EWI participants are not eligible to make additional after-tax
contributions or to receive an employer match or other employer contributions.

     Vesting and benefits.  The vesting schedule for participants allows for 20%
vesting of employer  contributions  following two years of service,  50% vesting
following three years of service,  75% vesting  following four years of service,
and 100% vesting  following five years of service.  A participant with less than
two  years  of  service  is  0%  vested  in  employer  contributions.   Employer
contributions are fully vested upon death, retirement or disability, as provided
in the Plan.

     Distributions  to participants  may occur upon termination or during active
service under prescribed circumstances.  Only lump sum distributions are allowed
under the Plan.

         Benefits are recorded when paid.

     Investments.  Investments  are recorded at fair value based upon the quoted
market price reported on the last trading day of the period for those securities
listed on a national  securities  exchange.  Listed securities for which no sale
was reported on that date are valued at the mean  between the last  reported bid
and ask prices. Short-term investments are stated at fair value.

     Purchases and sales of  investments  are  reflected on a trade-date  basis.
Gains or  losses on sales of  securities  are based on  average  cost.  The Plan
presents in the  statements of changes in net assets  available for benefits the
net  appreciation  (depreciation)  in the fair value of its  investments,  which
consists of realized gains or losses, and unrealized appreciation (depreciation)
on investments.

     Investment income. Income (loss) from investments is recorded on an accrual
basis. Dividend income is recorded on the ex-dividend date.

     Participants' accounts. During the year, participants could direct the Plan
administrator  to invest,  in 1% increments,  their account  balance in publicly
traded  registered   investment  companies  and  pooled  funds  which  are  both
administered  by Merrill  Lynch Trust Company  ("Merrill  Lynch") or NL's common
stock.  The Plan's assets were invested  principally in investment funds managed
by (i) Merrill Lynch, (ii) Massachusetts  Financial Services,  (iii) Oppenheimer
Funds  Distributor,  Inc., (iv) Harris  Associates  Securities L.P., (v) Calvert
Asset Management Company and (vi) State Street Research Funds.

     Participants  may  reallocate  investments  among the available  funds on a
daily basis.  With respect to investments in NL common stock,  participants  may
make only one purchase or sale per month. Prior to 2005,  participants were also
permitted  to  invest in the  common  stocks of  Kronos,  Valhi and  Halliburton
Company,  and during 2005 participants could only make sales, but not purchases,
of these common stocks.  Prior to the investment in one of the available  funds,
contributions  may be held as cash and  temporarily  invested in securities with
maturities of less than one year, issued or guaranteed by the U.S. government or
any agency or instrumentality thereof, or deposited in a bank savings account.

     On September  27, 2005  participants  were  notified that they would not be
able to hold the common stocks of NL, Kronos,  Valhi or  Halliburton  Company in
their  account  after  December 30,  2005.  No future  contributions  or account
transfers  could be made to the NL stock fund after October 7, 2005,  and if the
participant  had not  liquidated  the  balances  in the NL,  Kronos,  Valhi  and
Halliburton  stock  funds prior to December  16,  2005,  the Plan would begin to
liquidate  them and transfer  the  proceeds to the Merrill  Lynch Equity Index 1
Fund.

     In addition  to the  investment  funds  described  above,  a "Loan Fund" is
maintained  to account for loans to  participants,  as  permitted by the Plan. A
participant is able to borrow from his/her fund account an amount ranging from a
minimum  of $1,000  up to a maximum  that is  generally  equal to the  lesser of
$50,000 or 50% of his/her vested account balance.  A loan is  collateralized  by
the  balance  in  the   participant's   account  and  bears  interest  at  rates
commensurate  with local  prevailing  rates,  which  ranged  from 5.00% to 9.00%
during the year ended  December  31,  2005.  Principal  and  interest are repaid
ratably over a four- to five-year period through semimonthly payroll deductions.

     Each  participant's  account  is  credited  with  the  eligible  employee's
contribution and an allocation of the Employer's contribution and Plan earnings.
Allocations are based on participant earnings,  matching or account balances, as
defined in the Plan.

     Forfeitures.   Forfeitures  of  employer   contributions  may  occur  if  a
participant  terminates  employment and receives a  distribution  of his account
prior to the full vesting  period.  Amounts  forfeited are used in the following
order in  accordance  with Plan  provisions:  (i) to  restore  the  accounts  of
reemployed  participants,  (ii) to  restore  the  accounts  of  participants  or
beneficiaries  who apply for  forfeited  benefits  and (iii) to reduce  employer
contributions.  In 2005,  forfeitures were $13,140, and there were no forfeiture
reinstatements. The balance in the forfeiture account was $8,690 at December 31,
2004 and $44,911 at December 31, 2005 before transfer to the Retirement Plan. In
2005,   $19,000  of  the  forfeiture   account  was  used  to  reduce   employer
contributions for the prior year.

     Plan termination.  The Employer has the right under the Plan to discontinue
its  contributions  at any time and to terminate the Plan in compliance with the
provisions of ERISA.  In the event the Plan is  terminated,  the accounts of all
participants  will  become  fully  vested.  The  merger  of the  Plan  into  the
Retirement Plan (see Note 2) was not a termination of the Plan.

     Management estimates. The preparation of financial statements in accordance
with GAAP requires  management to make estimates and assumptions that affect the
reported amounts of assets, liabilities,  and changes therein, and disclosure of
contingent assets and liabilities. Actual results may, in some instances, differ
from previously estimated amounts.

     Risks and  uncertainties.  The Plan provides for various investment options
in a variety of stocks,  bonds, fixed income securities,  mutual funds and other
investment securities.  Investment securities are exposed to various risks, such
as interest rate,  market and credit risks.  Due to the level of risk associated
with certain  investment  securities,  it is at least  reasonably  possible that
changes in the values of investment  securities  will occur in the near term and
that such changes could materially affect participants' account balances and the
amounts reported in the Plan's statement of net assets available for benefits.

     Expenses of  administering  the Plan.  The Plan  provides that the Employer
will generally reimburse the Plan for administrative  expenses paid by the Plan.
The Employer paid all of the Plan's 2005 administrative expenses.

     Tax status. The Plan has been notified by the IRS, by letter dated December
12, 2002, that it is a qualified plan under Section 401(a) and Section 401(k) of
the Code, and is therefore  exempt from federal income taxes under provisions of
Section 501(a) of the Code.

     The Plan has been amended since it was notified of its exempt status by the
IRS.  Management  believes  the Plan  currently  is  designed  and  operates  in
accordance with the applicable  requirements  of the Code and therefore  remains
exempt from federal income taxes under provisions of Section 501(a) of the Code.

Note 2 - Plan Merger:

     On  December  31,  2005,  the Plan was  merged  into  the  Retirement  Plan
resulting in the transfer of net assets thereto of $20,272,038.  Participants of
the Plan began to participate in the Retirement Plan on January 1, 2006.

     The merger and  resulting  change in  custodians  initiated  a "Black  Out"
period  beginning  December 19, 2005 and  continuing  through  January 16, 2006.
During this period,  changes could not be made to participant accounts and funds
could not be withdrawn from either the Plan or the Retirement Plan.

Note 3 - Related-party transactions:

     Prior to December 31, 2005, certain Plan investments were held in shares of
mutual funds or common collective trusts managed by Merrill Lynch. Merrill Lynch
served as trustee for the Plan until December 31, 2005. Therefore,  transactions
involving these investments qualify as party-in-interest transactions.

     Three of the  available  fund  options  invested in the common stock of NL,
Kronos and Valhi.  The activity in these  securities for the year ended December
31, 2005 was as follows:
<TABLE>

                                             Sales and
                                           distributions,      Realized
                               Purchases      at cost         Gain (loss)      Fair value
                               ---------   --------------     -----------      ----------

<S>                             <C>           <C>              <C>              <C>
NL common stock                 $4,825        $425,730         $(102,075)       $    -
Kronos common stock                  -         120,130           200,301             -
Valhi common stock                   -           8,607            40,278             -
</TABLE>

     Dividend  income  received from related parties for the year ended December
31,  2005  consisted  of $15,350  from NL,  $11,619  from Kronos and $1,070 from
Valhi.

Note 4 - Investments:

     The Plan's  investments  are stated at fair  value  based on quoted  market
prices and net appreciation for the year is reflected in the Plan's statement of
changes in net assets available for benefits.  The net appreciation  consists of
realized  gains and losses  and  unrealized  appreciation  and  depreciation  on
investments. The following presents investments that represent 5% or more of the
Plan's net assets.
<TABLE>

                                                                                December 31,
                                                                        -----------------------------
                                                                           2004                2005
                                                                           ----                ----

<S>                                                                     <C>                  <C>
Merrill Lynch Retirement Preservation Trust                             $8,857,247           $     -
placeStateMassachusetts Financial Services Value Fund                    5,916,528                 -
Merrill Lynch Equity Index Trust                                         2,615,066                 -
Oakmark International Fund                                               1,966,013                 -
Oppenheimer Capital Appreciation Fund                                    1,725,733                 -
</TABLE>


     During  2005,  the  Plan's  investments  (including  gains  and  losses  on
investments  bought and sold,  as well as held during the year)  appreciated  by
$87,005 as follows:
<TABLE>

<S>                                                              <C>
Mutual funds                                                     $  211,538
Common stocks                                                      (246,985)
Common collective trusts                                            122,452
                                                                 ----------

                                                                 $   87,005
                                                                 ==========
</TABLE>


                                                                       EXHIBIT A


            CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM



We  hereby  consent  to the  incorporation  by  reference  in  the  Registration
Statement on Form S-8 (No. 33025913) of NL Industries,  Inc. of our report dated
June 2, 2006 relating to the financial  statements  of the NL  Industries,  Inc.
Retirement Savings Plan, which appears in this Form 11-K.





Sutton Frost Cary LLP
Dallas, Texas
June 28, 2006



                                                                       EXHIBIT B


            CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM



We  hereby  consent  to the  incorporation  by  reference  in  the  Registration
Statement on Form S-8 (No. 33025913) of NL Industries,  Inc. of our report dated
June 28, 2005 relating to the financial  statements of the NL  Industries,  Inc.
Retirement Savings Plan, which appears in this Form 11-K.







PricewaterhouseCoopers LLP
Dallas, Texas
June 28, 2006