SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                   ----------

                                   SCHEDULE TO
                                 (RULE 14d-100)

                  TENDER OFFER STATEMENT UNDER SECTION 14(d)(1)
           OR SECTION 13(e)(1) OF THE SECURITIES EXCHANGE ACT OF 1934
                                (AMENDMENT NO. 3)

                                   ----------

                    NATIONAL BANCSHARES CORPORATION OF TEXAS
                       (Name of Subject Company (Issuer))

                      INTERNATIONAL BANCSHARES CORPORATION
                              NBC ACQUISITION CORP.
                      (Names of Filing Persons (Offerors))

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                     COMMON STOCK, PAR VALUE $.001 PER SHARE
                         (Title of Class of Securities)

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                                 632-593-505-000
                      (CUSIP Number of Class of Securities)

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                                 DENNIS E. NIXON
                       CHAIRMAN OF THE BOARD AND PRESIDENT
                      INTERNATIONAL BANCSHARES CORPORATION
                             1200 SAN BERNARDO AVE.
                               LAREDO, TEXAS 78040
                            TELEPHONE: (956) 722-7611
           (Name, address and telephone number of person authorized to
         receive notices and communications on behalf of filing persons)

                                   COPIES TO:

                                CARY PLOTKIN KAVY
                            COX & SMITH INCORPORATED
                            112 E. PECAN, SUITE 1800
                            SAN ANTONIO, TEXAS 78205
                            TELEPHONE: (210) 554-5500

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                           CALCULATION OF FILING FEE:



TRANSACTION VALUATION*                                    AMOUNT OF FILING FEE**

                                                       
    $93,319,899.75                                                $18,664


*    For purposes of calculating the filing fee only. This calculation assumes
     the purchase of 3,770,501 shares of common stock of National Bancshares
     Corporation of Texas at the tender offer price of $24.75 per share of
     common stock.

**   The amount of the filing fee, calculated in accordance with Rule 0-11 of
     the Securities Exchange Act of 1934, as amended, equals 1/50 of 1% of the
     transaction valuation.

[X]  Check the box if any part of the fee is offset as provided by Rule
     0-11(a)(2) and identify the filing with which the offsetting fee was
     previously paid. Identify the previous filing by registration statement
     number, or the Form or Schedule and the date of its filing.


                                                
Amount Previously Paid:   $18,664        Filing Party:   International Bancshares Corporation
Form or Registration No.: SCHEDULE TO    Date Filed:     August 9, 2001


[ ]  Check the box if the filing relates solely to preliminary communications
     made before the commencement of a tender offer.

     Check the appropriate boxes to designate any transactions to which this
statement relates:

     [X] third-party tender offer subject to Rule 14d-1.
     [ ] issuer tender offer subject to Rule 13e-4.
     [ ] going-private transaction subject to Rule 13e-3.
     [ ] amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results
of the tender offer: [ ]

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     This Amendment No. 3 amends the Tender Offer Statement on Schedule TO
initially filed on August 9, 2001, and amended by Amendment No. 1 filed on
September 10, 2001 and Amendment No. 2 filed on October 1, 2001 (as amended, the
"Schedule TO"), by International Bancshares Corporation, a Texas corporation
("Parent"), and NBC Acquisition Corp., a Texas corporation and wholly-owned
subsidiary of Parent (the "Purchaser"), relating to the third-party tender offer
by Purchaser to purchase all the outstanding shares of Common Stock, par value
$.001 per share (the "Shares"), of National Bancshares Corporation of Texas, a
Texas corporation (the "Company"), at a price equal to $24.75 per Share, subject
to adjustment as described in the Offer to Purchase (as defined below), net to
the seller in cash, without interest thereon, upon the terms and subject to the
conditions set forth in the Offer to Purchase dated August 9, 2001 (the "Offer
to Purchase"), and in the related Letter of Transmittal (which together with any
supplements or amendments, collectively constitute the "Offer"), copies of which
were filed with the Schedule TO filed on August 9, 2001 as Exhibits (a)(1)(A)
and (a)(1)(C), respectively. This Amendment No. 3 is being filed on behalf of
the Purchaser and Parent. Capitalized terms used and not defined herein shall
have the meanings ascribed to such terms in the Offer to Purchase.

                                       2


ITEMS 4 AND 11(b).

     Items 4 and 11(b) of the Schedule TO, which incorporates by reference the
information contained in the Offer to Purchase, are hereby amended and
supplemented as follows:

     The Purchaser and Parent have further extended the Expiration Date of the
Offer until 5:00 p.m., New York City time, on November 7, 2001.

ITEM 12. EXHIBITS.

     Item 12 of the Schedule TO is hereby amended by including the following:

     (a)(1)(M) Press Release issued by Parent and the Purchaser on October 22,
               2001.

                                   SIGNATURES

     After due inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and correct.

                                      NBC ACQUISITION CORP.

                                      By: /s/ DENNIS E. NIXON
                                          --------------------------------------
                                      Name: Dennis E. Nixon
                                      Title: President

                                      INTERNATIONAL BANCSHARES
                                      CORPORATION

                                      By: /s/ DENNIS E. NIXON
                                          --------------------------------------
                                      Name: Dennis E. Nixon
                                      Title: Chairman of the Board and President

Dated: October 22, 2001

                                       3


                                INDEX TO EXHIBITS



 EXHIBIT
 NUMBER           EXHIBIT
 -------          -------

               
*(a)(1)(A)        Offer to Purchase dated August 9, 2001.

*(a)(1)(B)        Recommendation Statement on Schedule 14D-9 of the Company
                  dated August 9, 2001.

*(a)(1)(C)        Letter of Transmittal.

*(a)(1)(D)        Notice of Guaranteed Delivery.

*(a)(1)(E)        Letter to Brokers, Dealers, Banks, Trust Companies and Other
                  Nominees.

*(a)(1)(F)        Letter to Clients for use by Brokers, Dealers, Banks, Trust
                  Companies and Other Nominees.

*(a)(1)(G)        Guidelines for Certification of Taxpayer Identification Number
                  on Substitute Form W-9.

*(a)(1)(H)        Joint Press Release issued by Parent and the Company on July
                  31, 2001.

*(a)(1)(I)        Summary Advertisement published in the Wall Street Journal
                  August 9, 2001.

*(a)(1)(J)        Letter to Shareholders of the Company from the Chief Executive
                  Officer and President of the Company dated August 9, 2001.

*(a)(1)(K)        Press Release issued by Parent and the Purchaser on September
                  10, 2001.

*(a)(1)(L)        Press Release issued by Parent and the Purchaser on October 1,
                  2001.

(a)(1)(M)         Press Release issued by Parent and Purchaser on October 22,
                  2001.

(b)               Not applicable.

*(d)(1)           Agreement and Plan of Merger dated as of June 30, 2001, among
                  Parent, the Purchaser and the Company.

*(d)(2)           Confidentiality Agreement dated March 27, 2001, by and between
                  Parent and the Company

*(d)(3)           Agreement dated July 30, 2001, by and between Parent and Tamir
                  Hacker.

*(d)(4)           Agreement dated July 30, 2001, by and between Parent and
                  Marvin E. Melson.

*(d)(5)           Agreement dated July 30, 2001, by and between Parent and John
                  W. Lettunich.

*(d)(g)           Agreement dated July 30, 2001, by and between Parent and
                  Charles T. Meeks.

(g)               Not applicable.

(h)               Not applicable.


* Previously filed.