EXHIBIT 5.3




April 17, 2006

Mission West Properties, Inc.
10050 Bandley Drive
Cupertino, CA 95014

                       REGISTRATION STATEMENT ON FORM S-3

Ladies and Gentlemen:

     We have acted as counsel  for Mission  West  Properties,  Inc.,  a Maryland
corporation (the "Company"), in connection with the preparation of the Company's
Registration  Statement on Form S-3 proposed to be filed with the Securities and
Exchange Commission on or about April 17, 2006 (the "Registration Statement").

     The  Registration  Statement  covers the  registration  for resale of up to
86,088,095  shares of common stock,  $0.001 par value per share,  of the Company
(the  "Shares"),  which  might be  issued  in  exchange  for  units  of  limited
partnership interests ("O.P. Units") of Mission West Properties L.P., a Delaware
limited  partnership,  Mission  West  Properties  L.P.  I,  a  Delaware  limited
partnership,  Mission West Properties L.P. II, a Delaware  limited  partnership,
and  Mission  West   Properties  L.P.  III,  a  Delaware   limited   partnership
(collectively, the "Operating Partnerships"),  by the holders of the O.P. Units.
The O.P. Units may be tendered in redemption or exchange for the Shares upon the
conditions  set forth in the  agreement  of limited  partnership  of each of the
Operating  Partnerships  and as set forth in the Exchange Rights Agreement dated
as of December 29, 1998 among the Company,  the Operating  Partnerships  and the
holders of the O.P. Units (the "Exchange Rights Agreement").

     We have reviewed the corporate  proceedings  of the Company with respect to
the  authorization  of  the  Registration  Statement  and  the  Exchange  Rights
Agreement  and have  reviewed the limited  partnership  agreement of each of the
Operating  Partnerships.  We have also examined and relied upon such agreements,
instruments,  corporate  records,  certificates,  and other documents as we have
deemed  necessary  or  appropriate  as  a  basis  for  the  opinion  hereinafter
expressed.  In  our  examination,   we  have  assumed  the  genuineness  of  all
signatures,  the conformity to the originals of all documents  reviewed by us as
copies,  the authenticity and completeness of all original documents reviewed by
us in  original  or copy  form,  and the  legal  competence  of each  individual
executing any document.

     We further assume, without investigation, that all Shares will be issued in
accordance  with the terms of the  Exchange  Rights  Agreement  and the  limited
partnership agreements and that the purchase price of each of the Shares will be
at least equal to the par value of such Shares,  except as otherwise  authorized
in the future in accordance with the Maryland General Corporation Law.

     This opinion is limited solely to the Maryland  General  Corporation Law as
applied by courts located in Maryland, the applicable provisions of the Maryland
Constitution and the reported  judicial  decisions  interpreting  those laws, as
well  as to  applicable  provisions  of the  Delaware  Revised  Uniform  Limited
Partnership Act and California law in effect as of the date of this opinion.

         Based upon and subject to the foregoing, we are of the opinion that the
Shares, when issued and delivered upon the tender of O.P. Units for exchange or
redemption in accordance with the Exchange Rights Agreement and the limited
partnership agreements, will be validly issued, fully paid and non-assessable.




     We hereby  consent  to the filing of this  opinion  as  Exhibit  5.3 to the
Registration Statement,  and as an exhibit to any further registration statement
to be filed  pursuant to SEC Rule 462(b) with respect to the shares,  and to the
reference  to this firm under the  heading  "Legal  Matters"  in the  prospectus
included in the Registration Statement.  In giving this consent,  however, we do
not thereby admit that we are an "expert"  within the meaning of the  Securities
Act of 1933, as amended.



                                                    Very truly yours,

                                                    /s/ BINGHAM MCCUTCHEN LLP
                                                    ----------------------------
                                                    BINGHAM MCCUTCHEN LLP