EXHIBIT 31.2
                                 CERTIFICATIONS

I, Mary Dieter Smith, certify that:

     1.   I have reviewed this Form 10-Q of Sonoma Valley Bancorp;

     2.   Based on my  knowledge,  this  report  does  not  contain  any  untrue
          statement  of a  material  fact  or  omit to  state  a  material  fact
          necessary to make the statements  made, in light of the  circumstances
          under which such  statements were made, not misleading with respect to
          the period covered by this report;

     3.   Based on my knowledge,  the financial statements,  and other financial
          information  included in this report,  fairly  present in all material
          respects the financial condition, results of operations and cash flows
          of the  registrant  as of,  and for,  the  periods  presented  in this
          report;

     4.   The registrant's other certifying officer(s) and I are responsible for
          establishing  and maintaining  disclosure  controls and procedures (as
          defined  in  Exchange  Act  Rules  13a-15(e)  and  15d-15(e))  for the
          registrant and have:

               (a) Designed such disclosure  controls and procedures,  or caused
               such disclosure  controls and procedures to be designed under our
               supervision,  to ensure that material information relating to the
               registrant,  including  its  consolidated  subsidiaries,  is made
               known to us by others within those entities,  particularly during
               the period in which this report is being prepared;

               (b) omitted;

               (c) Evaluated the  effectiveness of the  registrant's  disclosure
               controls  and   procedures  and  presented  in  this  report  our
               conclusions  about the  effectiveness of the disclosure  controls
               and  procedures,  as of the  end of the  period  covered  by this
               report based on such evaluation; and

               (d)  Disclosed  in this  report  any  change in the  registrant's
               internal  control over financial  reporting that occurred  during
               the  registrant's  most recent fiscal  quarter (the  registrant's
               fourth fiscal  quarter in the case of an annual  report) that has
               materially  affected,  or  is  reasonably  likely  to  materially
               affect,   the   registrant's   internal  control  over  financial
               reporting; and

     5.   The  registrant's  other  certifying  officer(s) and I have disclosed,
          based on our most recent evaluation of internal control over financial
          reporting, to the registrant's auditors and the audit committee of the
          registrant's  board of directors (or persons performing the equivalent
          functions):

               (a) All significant  deficiencies and material  weaknesses in the
               design or operation of internal control over financial  reporting
               which are reasonably  likely to adversely affect the registrant's
               ability  to  record,  process,  summarize  and  report  financial
               information; and

               (b) Any fraud, whether or not material,  that involves management
               or  other   employees  who  have  a   significant   role  in  the
               registrant's internal control over financial reporting.

Dated: November 10, 2004                             /s/ Mary Dieter Smith
       -----------------                             ---------------------------
                                                     Mary Dieter Smith
                                                     Executive Vice President,
                                                     Chief Operating Officer and
                                                     Chief Financial Officer
                                                     (Principal Financial and
                                                     Accounting Officer)