UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION,
                             WASHINGTON, D.C. 20549
                           ---------------------------

                                SCHEDULE TO-I/A-4

            TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) or 13(e)(1)
                     OF THE SECURITIES EXCHANGE ACT OF 1934

                              Sonoma Valley Bancorp
                              ---------------------
                       (Name of Subject Company (Issuer))

                              Sonoma Valley Bancorp
                              ---------------------
                        (Name of Filing Person (Issuer))

                           Common Stock, No Par Value
                           --------------------------
                         (Title of Class of Securities)

                                   835592 106
                                   ----------
                      (CUSIP Number of Class of Securities)

                                Mel Switzer, Jr.
                      President and Chief Executive Officer
                               202 W. Napa Street
                            Sonoma, California 95476
                                 (707) 935-3200
                                 --------------
          (Name, address and telephone numbers of persons authorized to
         receive notices and communications on behalf of filing persons)

                                    Copy to:

                                  Daniel B. Eng
                                 David C. Adams
                              Bartel Eng & Schroder
                         1331 Garden Highway, Suite 300
                          Sacramento, California 95833
                                 (916) 442-0400

                            CALCULATION OF FILING FEE
                  Transaction valuation* Amount of filing fee**
                               $3,500,000 $443.45

* Calculated  solely for the purpose of determining the filing fee in accordance
with Rule 0-11(b)(1). This calculation assumes the purchase of 100,000 shares at
$35.00 per share.

 **  Previously paid

[ ]  Check  the  box if any  part  of the  fee is  offset  as  provided  by Rule
     011(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:  Not applicable
         Form or Registration Number:  Not applicable
         Filing Party:  Not applicable
         Date Filed:  Not applicable

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

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

[ ]  third party tender offer subject to Rule 14d-1.

[X]  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 a tender offer: ?

Introductory Statement

This is Amendment  No. 4 to the issuer  tender offer of Sonoma  Valley  Bancorp,
Inc., a California corporation, (the "Company") to purchase up to 100,000 shares
of its common  stock,  no par value.  The Company is offering to purchase  these
shares at $35.00 per share, net to the seller in cash,  without  interest,  upon
the terms and subject to the conditions set forth in the Offer to Purchase dated
April 6, 2004, Supplement No.2 to the Offer to Purchase dated April 29, 2004 and
in the related Letter of Transmittal,  which,  as amended or  supplemented  from
time to time,  together  constitute  the "Offer."  This  Amendment  No. 4 to the
issuer  tender offer on Schedule TO is filed in  satisfaction  of the  reporting
requirements of Rule 13e-4(c)(1)  promulgated under the Securities  Exchange Act
of 1934, as amended.

On May 12, 2004, the Company extended the expiration date of the Offer from 2:00
p.m. (EST) on May 14, 2004 to the new expiration  date of 2:00 p.m. (EST) on May
21, 2004.  The Company is extending the Offer  because there was a  distribution
problem  that delayed the mailing of the Offer  documents to some  shareholders.
The problem was corrected;  however, the Company is extending the Offer to allow
all shareholders  ample time to consider whether they wish to participate in the
Offer and to tender their shares.  A copy of the press release has been filed as
Exhibit (a)(5)(iii) to this Schedule TO/A-4.


ITEM 12. EXHIBITS.

         (a)(1)(i)    Offer to Purchase, dated April 6, 2004.(1)

         (a)(1)(ii)   Letter of Transmittal, together with Guidelines for
                      Certification of Taxpayer Identification Number on
                      Substitute Form W-9. (1)

         (a)(1)(iii)  Letter to Shareholders of Sonoma Valley Bancorp from Mel
                      Switzer, Jr., President and Chief Executive Officer, dated
                      April 6, 2004. (1)

         (a)(1)(iv)   Notice of Guaranteed Delivery. (1)

         (a)(1)(v)    Letter to Brokers, Dealers, Commercial Banks, Trust
                      Companies and Other Nominees, dated April 6, 2004. (1)

         (a)(1)(vi)   Letter to Clients for use by Brokers, Dealers, Commercial
                      Banks, Trust Companies and Other Nominees to their
                      Clients, dated April 6, 2004. (1)

         (a)(1)(vii)  Supplement Number 1 to the Offer to Purchase, dated April
                      22, 2004. (2)

         (a)(1)(viii) Supplement Number 2 to the Offer to Purchase dated April
                      29, 2004. (3)

         (a)(5)(i)    Press Release dated April 6, 2004. (1)

         (a)(5)(ii)   Press Release dated May 5, 2004 announcing supplemental
                      information to the Offer to Purchase. (4)

         (a)(5)(iii)  Press Release dated May 12, 2004 announcing supplemental
                      information to the Offer to Purchase.

         (b)          Not applicable

         (c)          Not applicable

         (d)          Not applicable

         (e)          Not applicable

         (f)          Not applicable

         (g)          Not applicable

         (h)          Not applicable

(1) Incorporated by reference from Schedule TO-I filed on April 6, 2004.


(2) Incorporated by reference from Schedule TO-I/A-1 filed on April 22, 2004.
(3) Incorporated by reference from Schedule TO-I/A-2 filed on April 29, 2004.
(4) Incorporated by reference from Schedule TO-I/A-3 filed on May 5, 2004.






                                    SIGNATURE


     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.

Date:    May 12, 2004                   SONOMA VALLEY BANCORP



                                        By: /s/ Mel Switzer, Jr.
                                           -------------------------------
                                           Mel Switzer, Jr.,
                                           President and Chief Executive Officer
                                           (Principal Executive Officer)