EXHIBIT
31.2
 CERTIFICATION
 
 I, Mary
Dieter Smith, certify that:
  1.  I have reviewed this Form 10-K 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 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)Designed such internal
control over financial reporting, or caused such internal control over financial
reporting to be designed under our supervision, to provide reasonable assurance
regarding the reliability of financial reporting and the preparation of
financial statements for external purposes in accordance with generally accepted
accounting principles;
  (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:
      March
      18, 2009
                /s/ Mary Dieter
      SmithMary
      Dieter SmithChief
      Financial Officer(Principal
      Finance and Accounting Officer)