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                      SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549

                                  FORM 10-K/A

[X]      ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
         EXCHANGE ACT OF 1934

         For the Fiscal Year Ended September 30, 1999 OR

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

                       Commission File Number: 0-26632

                             InterWest Bancorp, Inc.
              ----------------------------------------------------
             (Exact name of registrant as specified in its charter)



Washington                                                   91-1691216
-------------------------------                          -------------------
(State or other jurisdiction of                          (I.R.S. Employer
incorporation or organization)                           Identification No.)

275 Southeast Pioneer Way, Oak Harbor, Washington           98277
-------------------------------------------------        ------------
(Address of principal executive offices)                  (Zip Code)

Registrant's telephone number, including area code       (360) 679-4181
                                                         --------------

Securities registered pursuant to Section 12(b) of the Act: None
                                                            ----

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



                     Common Stock, no par value per share
                     ------------------------------------
                                (Title of Class)

         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 (or for such shorter period that the
Registrant was required to file such reports), 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.
                              ---

         The aggregate market value of the voting stock held by non-affiliates
of the Registrant was $278,281,920 based upon the closing price of the
Registrant's common stock as quoted on the Nasdaq National Market on December
20, 1999 of $17.50.

         As of December 20, 1999, there were issued and outstanding 15,901,824
shares of the Registrant's common stock.

                       DOCUMENTS INCORPORATED BY REFERENCE

         1. Selected Consolidated Financial Data, Management Discussion and
Analysis and Consolidated Financial Statements included in the Annual Report to
Shareholders for the year ended September 30, 1999. (Part II).

         2. Proxy Statement for the 2000 Annual Meeting of Shareholders ("Proxy
Statement"). (Part III).


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                                    PART IV

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

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(a)      (1)      Consolidated Financial Statements

                  Independent Auditors' Report

         (a)      Consolidated Statements of Financial Condition as of
                  September 30, 1999 and 1998
         (b)      Consolidated Statements of Income For the Years Ended
                  September 30, 1999, 1998 and 1997
         (c)      Consolidated Statements of Shareholders' Equity For the Years
                  Ended September 30, 1999, 1998 and 1997
         (d)      Consolidated Statements of Cash Flows For the Years Ended
                  September 30, 1999, 1998 and 1997
         (e)      Notes to Consolidated Financial Statements
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         Notes to Consolidated Financial Statements

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<S>     <C>      <C>
         (2)      All required financial statement schedules are included in
                  the Notes to Consolidated Financial Statements.
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<S>     <C>      <C>
                  Consolidated Financial Statements and Notes to Consolidated
                  Financial Statements are included in Exhibit 13 herein.
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(b)      Reports on Form 8-K


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         Bancorp filed a Form 8-K dated September 14, 1999, to report the
         entering of a definitive agreement to acquire Liberty Bay Financial
         Corporation.
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<S>     <C>         <C>

(c)      EXHIBITS

         (3.1)      Articles of Incorporation of InterWest Bancorp, Inc.
                    (incorporated by reference to the Registrant's Annual
                    Report on Form 10-K for the year ended September 30, 1998)
         (3.2)      Bylaws of InterWest Bancorp, Inc. (incorporated by reference
                    to the Registrant's Annual Report on Form 10-K for the year
                    ended September 30, 1998)
         (10.1)     Employment Agreement with B. R. Beeksma (incorporated by
                    reference to the Registrant's Annual Report on Form 10-K for
                    the year ended September 30, 1995)
         (10.2)     Employment Agreement with Stephen M. Walden (incorporated
                    by reference to the Registrant's Annual Report on Form 10-K
                    for the year ended September 30, 1995)
         (10.3)     Employment Agreement with H. Glenn Mouw (incorporated by
                    reference to the Registrant's Annual Report on Form 10-K for
                    the year ended September 30, 1995)
         (10.4)     Employment Agreement with Clark W. Donnell (incorporated by
                    reference to the Registrant's Annual Report on Form 10-K
                    for the year ended September 30, 1995)
         (10.5)     Employment Agreement with Kenneth G. Hulett (incorporated by
                    reference to the Registrant's Annual Report on Form 10-K for
                    the year ended September 30, 1995)
         (10.6)     1984 Stock Option Plan (incorporated by reference to Exhibit
                    99.1 to the Registrant's Registration Statement on Form S-8
                    (File No. 33-99742))
         (10.7)     InterWest Bancorp, Inc. Amended and Restated 1993 Incentive
                    Stock Option Plan (incorporated by reference to the
                    Registrant's Annual Report on Form 10-K for the year ended
                    September 30, 1998)
         (10.8)     Non-Incentive Stock Option Plan for Outside Directors
                    (incorporated by reference to Exhibit 99.2 to the
                    Registrant's Registration Statement on Form S-8
                    (File No. 33-99742))
         (10.9)     Employment Agreement with Gary M. Bolyard (incorporated by
                    reference to the Registrant's Annual Report on Form 10-K for
                    the year ended September 30, 1996)
         (10.10)    Central Bancorporation 1992 Employee Stock Option Plan
                    (incorporated by reference to Exhibit 99.2 to the
                    Registrant's Registration Statement on Forms S-8
                    (File No. 333-13191)).
         (10.11)    Central Bancorporation Director Stock Option Plan
                    (incorporated by reference to Exhibit 99.1 to the
                    Registrant's Registration Statement on Form S-8
                    (File No. 333-13191)).
         (10.12)    1996 Outside Directors Stock Options-for-Fees Plan
                    (incorporated by reference to Exhibit 99.1 to the
                    Registrant's Registration Statement on Form S-8
                    (File No. 333-24525))
         (10.13)    Employment Agreement with Patrick M. Fahey (incorporate by
                    reference to Exhibit 10.2 to the Registrant's Registration
                    Statement on Form S-4 (File No. 333-49131))
         (10.14)    First National Bank of Port Orchard 1990 Employee and
                    Director Stock Option Plan (incorporated by reference to
                    Exhibit 99.1 to the Registrant's Registration Statement on
                    Form S-8 (File No. 333-50685))
         (10.15)    Pacific Northwest Bank 1988 Stock Option Plan (incorporated
                    by reference to Exhibit 99.1 to the Registrant's
                    Registration Statement on Form S-8 (File No. 333-57679))
         (10.16)    Pioneer Bancorp, Inc. Amended and Restated Incentive Stock
                    Option Plan (incorporated by reference to Exhibit 99.2 to
                    the Registrant's Registration Statement on Form S-8
                    (File No. 333-57679))
         (10.17)    Kittitas Valley Bancorp 1996 Director Stock Option Plan
                    (incorporated by reference to Exhibit 99.1 to the
                    Registrant's Registration Statement on Form S-8
                    (File No. 333-65839))
         (10.18)    Kittitas Valley Bancorp Employee Stock Option Plan
                    (incorporated by reference to Exhibits 99.2 and 99.3 to the
                    Registrant's Registration Statement on Form S-8
                    (File No. 333-65839))
         (10.19)    Form of Severance Pay Agreement entered into between
                    InterWest Bank and Stephen M. Walden, H. Glenn Mouw, Clark
                    W. Donnell and Kenneth G. Hulett

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         (13)       Selected Consolidated Financial Data, Management Discussion
                    and Analysis and Consolidated Financial Statements included
                    in the 1999 Annual Report to Shareholders
         (21)       Subsidiaries of the Registrant
         (23.1)     Consent of Independent Auditors
         (27)       Financial Data Schedule



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                                   SIGNATURES

         Pursuant to the requirements of Section 13 or 15(d) of the
Securities Exchange Act of 1934, InterWest Bancorp, Inc. has duly caused this
report to be signed on its behalf by the undersigned, thereunto duly
authorized.

                                      InterWest Bancorp, Inc.

 Date:  December 30, 1999             By:    /s/ Stephen M. Walden
                                           -------------------------------------
                                           Stephen M. Walden
                                           President and Chief Executive Officer
                                           (Principal Executive Officer)

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