<PAGE>
 
      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 28, 1997
                                                      Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                               _________________

                                    FORM S-8
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                               _________________

                    SOUTHWEST BANCORPORATION OF TEXAS, INC.
             (Exact name of registrant as specified in its charter)

          TEXAS                                      76-0519693
(State or other jurisdiction of                   (I.R.S. Employer
incorporation or organization)                   Identification No.)


                             4400 POST OAK PARKWAY
                              HOUSTON, TEXAS 77027
          (Address of principal executive offices, including zip code)

                               _________________

                  SOUTHWEST BANK OF TEXAS 401(K) SAVINGS PLAN
                            (Full title of the plan)

                                DAVID C. FARRIES
                            EXECUTIVE VICE PRESIDENT
                    SOUTHWEST BANCORPORATION OF TEXAS, INC.
                             4400 POST OAK PARKWAY
                              HOUSTON, TEXAS 77027
                    (Name and address of agent for service)

                                 (713) 235-8800
         (Telephone number, including area code, of agent for service)

                                   Copies to:

                                Michael P. Finch
                             Vinson & Elkins L.L.P.
                             2300 First City Tower
                               1001 Fannin Street
                           Houston, Texas 77002-6760

                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
====================================================================================
     TITLE OF         AMOUNT         PROPOSED            PROPOSED        AMOUNT OF
 SECURITIES TO BE     TO BE      MAXIMUM OFFERING    MAXIMUM AGGREGATE  REGISTRATION
  REGISTERED (1)    REGISTERED  PRICE PER SHARE (2)   OFFERING PRICE        FEE
------------------------------------------------------------------------------------
<S>                    <C>         <C>                  <C>                <C>
Common Stock,
$1.00 par value        250,000       $23.675            $5,918,750       $1,794.00
====================================================================================
</TABLE>

(1)  Pursuant to Rule 416(c) under the Securities Act of 1933, this Registration
     Statement also covers an indeterminate amount of interests in the Plan
     named above.

(2)  Estimated, solely for purposes of calculating the registration fee, in
     accordance with Rule 457(h).
<PAGE>
 
                                    PART II
               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.    INCORPORATION OF DOCUMENTS BY REFERENCE.

     The following documents which have been filed with the Securities and
Exchange Commission (the "Commission") by Southwest Bancorporation of Texas,
Inc., a Texas corporation (the "Company"), are incorporated herein by reference
and made a part hereof:

     (a)  The Company's Annual Report on Form 10-K for the year ended December
          31, 1996.

     (b)  The Company's Quarterly Report on Form 10-Q for the three month period
          ended March 31, 1997.

     (c)  Description of the Common Stock contained in the Company's Prospectus
          dated January 27, 1997 (the "Prospectus"), included in the Company's
          Registration Statement on Form S-1 (Registration Statement No. 333-
          16509).

     All documents filed by the Company and the Plan pursuant to Sections 13(a)
and 15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange
Act"), subsequent to the effective date of this Registration Statement, prior to
the filing of a post-effective amendment to this Registration Statement
indicating that all securities offered hereby have been sold or deregistering
all securities then remaining unsold, shall be deemed to be incorporated by
reference herein and to be a part hereof from the date of filing of such
documents.  Any statement contained herein or in any document incorporated or
deemed to be incorporated by reference herein shall be deemed to be modified or
superseded for purposes of this Registration Statement to the extent that a
statement contained in any other subsequently filed document which also is or is
deemed to be incorporated by reference herein modifies or supersedes such
statement.  Any such statement so modified or superseded shall not be deemed to
constitute a part of this Registration Statement, except as so modified or
superseded.

ITEM 4.    DESCRIPTION OF SECURITIES.

     Not applicable.

ITEM 5.    INTERESTS OF NAMED EXPERTS AND COUNSEL.

     Not applicable.

ITEM 6.    INDEMNIFICATION OF DIRECTORS AND OFFICERS.

     The Articles of Incorporation of the Company provide that, subject to
certain limitations, its officers and directors (and certain other individuals
acting on behalf of the Company) will be indemnified by the Company against
judgments, penalties, fines, settlements and reasonable expenses actually
incurred by such persons, to the fullest extent permitted under the Texas
Business Corporation Act (the "TBCA").  Generally, Article 2.02-1 of the TBCA
permits a corporation to indemnify a person who was, is, or is threatened to be
made a named defendant or respondent in a proceeding because the person was or
is a director or officer if it is determined that such person (i) conducted
himself in good faith, (ii) reasonably believed (a) in the case of conduct in
his official capacity as a director or officer of the corporation, that his
conduct was in the corporation's best interest, or (b) in other cases, that his
conduct was at least not opposed to the corporation's best interests, and (iii)
in the case of any criminal proceeding, had no reasonable cause to believe that
his conduct was unlawful.  In addition, the TBCA requires a corporation to
indemnify a director or officer for any action that such director or officer is
wholly successful in defending on the merits.

     The Company's Articles of Incorporation provide that a director of the
Company will not be liable to the corporation for monetary damages for an act or
omission in the director's capacity as a director, except to the extent not
permitted by law.  Texas law does not permit exculpation of liability in the
case of (i) a breach of the director's duty of loyalty to the corporation or the
shareholders, (ii) an act or omission not in good faith that involves
intentional misconduct or a knowing violation of the law, (iii) a transaction
from which a director received an improper benefit,


                                      -2-
<PAGE>
 
whether or not the benefit resulted from an action taken within the scope of the
director's office, (iv) an action or omission for which the liability of the
director is expressly provided by statute, or (v) an act related to an unlawful
stock repurchase or dividend.

ITEM 7.   EXEMPTION FROM REGISTRATION CLAIMED.

     Not applicable.

ITEM 8.   EXHIBITS.

          *4.1  Articles of Incorporation of the Company (Exhibit 3.1).

          *4.2  Amendment dated December 18, 1996 to Articles of Incorporation
                of the Company (Exhibit 3.3).

          *4.3  Bylaws of the Company, restated as of December 31, 1996 (Exhibit
                3.2).

           4.4  Southwest Bank of Texas 401(k) Savings Plan as amended and
                restated as of January 1, 1994 (the "401(k) Plan").

           4.5  First Amendment to the 401(k) Plan, dated November 15, 1994.

           4.6  Second Amendment of the 401(k) Plan, dated January 1, 1996.

           4.7  Third Amendment to the 401(k) Plan, dated December 17, 1996.

           4.8  Fourth Amendment to the 401(k) Plan, dated May 1, 1997.

           5.1  Opinion of Vinson & Elkins L.L.P.

          23.1  Consent of Coopers & Lybrand L.L.P.

          23.2  Consent of Vinson & Elkins L.L.P. (included in Exhibit 5.1).

          24.1  Powers of Attorney (included on signature page).
_____________________________

*    Incorporated by reference to the Exhibit number shown in parentheses filed
     with the Company's Form S-1 Registration Statement No. 333-16509.

     The Registrant has submitted the Plan and will submit all amendments
thereto to the Internal Revenue Service ("IRS") in a timely manner and has made
or will make all changes thereto required by the IRS in order to qualify the
Plan.

ITEM 9.   UNDERTAKINGS.

     The undersigned Registrant hereby undertakes:

     (1) To file, during any period in which offers or sales are being made, a
post-effective amendment to this Registration Statement:

          (i) To include any prospectus required by Section 10(a)(3) of the
     Securities Act of 1933, as amended (the "1933 Act");

          (ii) To reflect in the prospectus any facts or events arising after
     the effective date of the Registration Statement (or the most recent post-
     effective amendment thereof) which, individually or in the aggregate,
     represent a fundamental change in the information set forth in the
     Registration Statement;

          (iii)  To include any material information with respect to the plan of
     distribution not previously disclosed in the Registration Statement or any
     material change to such information in the Registration Statement;

provided, however, that paragraphs (1)(i) and (1)(ii) do not apply if the
information required to be included in a post-effective amendment by those
paragraphs is contained in periodic reports filed by the Registrant pursuant to
Section 13 or Section 15(d) of the Exchange Act that are incorporated by
reference in the Registration Statement.


                                      -3-
<PAGE>
 
     (2) That, for the purpose of determining any liability under the 1933 Act,
each such post-effective amendment shall be deemed to be a new registration
statement relating to the securities offered therein, and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof.

     (3) To remove from registration by means of a post-effective amendment any
of the securities being registered which remain unsold at the termination of the
offering.

     The undersigned Registrant hereby undertakes that, for the purposes of
determining any liability under the 1933 Act, each filing of the Registrant's
annual report pursuant to Section 13(a) or Section 15(d) of the Exchange Act
(and, where applicable, each filing of an employee benefit plan's annual report
pursuant to Section 15(d) of the Exchange Act) that is incorporated by reference
in the Registration Statement shall be deemed to be a new Registration Statement
relating to the securities offered therein, and the offering of such securities
at that time shall be deemed to be the initial bona fide offering thereof.

     Insofar as indemnification for liabilities arising under the 1933 Act may
be permitted to directors, officers and controlling persons of the Registrant
pursuant to the foregoing provisions, or otherwise, the Registrant has been
advised that in the opinion of the Securities and Exchange Commission such
indemnification is against public policy as expressed in the 1933 Act and is,
therefore, unenforceable.  In the event that a claim for indemnification against
such liabilities (other than the payment by the Registrant of expenses incurred
or paid by a director, officer or controlling person of the Registrant in the
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the 1933 Act and will be governed by the final
adjudication of such issue.


                                      -4-
<PAGE>
 
                                   SIGNATURES

     PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, AS AMENDED, THE
REGISTRANT CERTIFIES THAT IT HAS REASONABLE GROUNDS TO BELIEVE THAT IT MEETS ALL
OF THE REQUIREMENTS FOR FILING ON FORM S-8 AND HAS DULY CAUSED THIS REGISTRATION
STATEMENT TO BE SIGNED ON ITS BEHALF BY THE UNDERSIGNED, THEREUNTO DULY
AUTHORIZED, IN THE CITY OF HOUSTON, STATE OF TEXAS, ON THE 28TH DAY OF MAY,
1997.

                                    SOUTHWEST BANCORPORATION OF TEXAS,
                                       INC.


                                    By: /s/  WALTER E. JOHNSON
                                       -----------------------------------
                                         Chairman of the Board and
                                           Chief Executive Officer

     KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints Paul B. Murphy, Jr., David C. Farries and R. John
McWhorter, or any of them, his true and lawful attorney-in-fact and agent, with
full power of substitution, for him and in his name, place and stead, in any and
all capacities, to sign any and all amendments (including post-effective
amendments) to this Registration Statement, and to file the same with all
exhibits thereto, and other documents in connection therewith, with the
Securities and Exchange Commission, granting unto said attorney-in-fact and
agent full power and authority to do and perform each and every act and thing
requisite and ratifying and confirming all that said attorney-in-fact and agent
or his substitute or substitutes may lawfully do or cause to be done by virtue
hereof.

     PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, AS AMENDED,
THIS REGISTRATION STATEMENT HAS BEEN SIGNED BY THE FOLLOWING PERSONS IN THE
CAPACITIES AND ON THE DATES INDICATED.

<TABLE>
<CAPTION>
 
         SIGNATURE                               TITLE                            DATE
         ---------                               -----                            ----
<S>                                <C>                                        <C>
 
     /s/  WALTER E. JOHNSON          Chairman of the Board and Chief            May 28, 1997
---------------------------------    Executive Officer (Principal Executive 
          Walter E. Johnson          Officer)
 

     /s/   DAVID C. FARRIES          Executive Vice President, Treasurer and    May 28, 1997
---------------------------------    Secretary (Principal Financial Officer)
           David C. Farries 

     /s/   R. JOHN McWHORTER         Vice President and Controller              May 28, 1997
---------------------------------    (Principal Accounting Officer)
           R. John McWhorter 

     /s/   J. DAVID HEANEY           Director                                   May 28, 1997
---------------------------------
           J. David Heaney 

     /s/   JOHN W. JOHNSON           Director                                   May 28, 1997
---------------------------------
           John W. Johnson 

     /s/   JOHN B. BROCK III         Director                                   May 28, 1997
---------------------------------
           John B. Brock III 

     /s/   ERNEST H. COCKRELL        Director                                   May 28, 1997
---------------------------------
           Ernest H. Cockrell 

     /s/   WILHELMINA R. MORIAN      Director                                   May 28, 1997
---------------------------------
           Wilhelmina R. Morian 

     /s/   PAUL B. MURPHY, JR.       Director and President                     May 28, 1997
---------------------------------
           Paul B. Murphy, Jr. 

     /s/  ANDRES PALANDJOGLOU        Director                                   May 28, 1997
---------------------------------
          Andres Palandjoglou 

     /s/   MICHAEL T. WILLIS         Director                                   May 28, 1997
---------------------------------
           Michael T. Willis 
 
</TABLE>



                                      -5-