Exhibit 31.1


                             CERTIFICATE PURSUANT TO
                 RULE 13a-14 THE SECURITIES EXCHANGE ACT OF 1934


I, Carl E. Berg, certify that:

1.   I have  reviewed  this Form 10-Q of Mission West  Properties,  Inc. for the
     quarterly period ended June 30, 2003;

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) 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


     (c)  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.



Carl E. Berg
Chairman and CEO

August 12, 2003