EXHIBIT 10.32.1

Loan No. 332757

                       FIRST AMENDMENT TO PROMISSORY NOTE
                         (Mission West Properties, L.P.)

     THIS FIRST AMENDMENT TO PROMISSORY NOTE (this "First Amendment") is made as
of the 5th day of  November,  2008  between,  MISSION WEST  PROPERTIES,  L.P., a
Delaware limited partnership,  10050 Bandley Drive,  Cupertino, CA 95014, herein
called  "Borrower",  and THE  NORTHWESTERN  MUTUAL  LIFE  INSURANCE  COMPANY,  a
Wisconsin corporation,  720 East Wisconsin Avenue,  Milwaukee,  Wisconsin 53202,
hereinafter called "Northwestern".

                                    RECITALS

     WHEREAS, Northwestern is the owner of a certain Promissory Note executed by
MISSION  WEST  PROPERTIES,  L.P.  on January 3, 2003 in the  original  principal
amount of TWENTY-EIGHT  MILLION EIGHT HUNDRED  SIXTY-EIGHT  THOUSAND SIX HUNDRED
FIFTY-FIVE  DOLLARS  ($28,868,655.00)  (the  "Note")  secured  by,  among  other
security,  i) a lien against certain property in the County of Santa Clara, City
of San Jose, State of California as more particularly  described in that certain
Deed of Trust and Security  Agreement  (First  Priority)  dated  January 3, 2003
executed by Borrower  and recorded  January 9, 2003 as Document No.  16735201 in
the records of Santa Clara County,  California, as amended by that certain First
Amendment to Deed of Trust and Security  Agreement  (First  Priority)  and First
Amendment to Deed of Trust and Security  Agreement  (Second  Priority) and First
Amendment to Absolute Assignment of Leases and Rents dated of even date herewith
between Lender and Borrower (the "Lien Instrument");  ii) a lien against certain
property  in the  County  of  Santa  Clara,  City of  Santa  Clara  and  City of
Cupertino,  State of California,  as more particularly described in that certain
Deed of Trust and Security  Agreement and Assignment of Leases and Rents (Second
Priority)  dated January 3, 2003,  executed by Mission West  Properties,  L.P. I
("MWI") and recorded  January 9, 2003 as Document No. 16735208 in the records of
Santa Clara County,  California,  as amended by that certain First  Amendment to
Deed of Trust and Security  Agreement  (First  Priority) and First  Amendment to
Deed of Trust and Security  Agreement  (Second  Priority) and First Amendment to
Absolute  Assignment  of Leases and Rents  dated of even date  herewith  between
Lender  and MWI (the "MWI  Second  Lien  Instrument");  and iii) a lien  against
certain property in the County of Santa Clara,  City of San Jose and the City of
Milpitas,  State of  California as more  particularly  described in that certain
Deed of Trust and Security  Agreement and Assignment of Leases and Rents (Second
Priority)  dated  January 3, 2003 executed by Mission West  Properties,  L.P. II
("MWII") and recorded January 9, 2003 as Document No. 16735203 in the records of
Santa Clara County,  California,  as amended by that certain First  Amendment to
Deed of Trust and Security  Agreement  (First  Priority) and First  Amendment to
Deed of Trust and Security  Agreement  (Second  Priority) and First Amendment to
Absolute  Assignment  of Leases and Rents  dated of even date  herewith  between
Lender and MWII (the "MWII Second Lien Instrument");

     AND WHEREAS, Northwestern has agreed to amend certain terms of the Note.

     NOW, THEREFORE,  in consideration of the above and of the mutual agreements
herein contained, the undersigned parties agree to the following:

     1. Unless  otherwise  defined  herein or otherwise  indicated,  capitalized
words and terms used but not defined  herein shall have the meaning  ascribed to
them in the Note.

     2. The amount of the  Promissory  Note shall be amended  from  TWENTY-EIGHT
MILLION  EIGHT  HUNDRED  SIXTY-EIGHT  THOUSAND  SIX HUNDRED  FIFTY-FIVE  DOLLARS
($28,868,655.00) TO FORTY-EIGHT  MILLION NINE HUNDRED SIXTY-EIGHT  THOUSAND FIVE
HUNDRED FORTY-ONE DOLLARS ($48,968,541.00).

     3. The monthly  payment  amount of principal and interest  shall be amended
from $200,874.00 to $417,426.00.

     4.  Schedule 1 attached  to the Note is deleted and  replaced  with the new
Schedule 1 attached hereto.

     5. This First Amendment may be executed in two or more  counterparts,  each
of which shall be deemed an  original,  and it shall not be  necessary in making
proof of this First  Amendment  to  produce  or  account  for more than one such
counterpart.  Separate  counterparts  of this First Amendment may be executed by
the parties  hereto to the same effect as if all the  parties had  executed  the
same counterpart.

     6. Except as hereby amended the Note shall remain in full force and effect,
unchanged and in all respects, ratified and confirmed.


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<PAGE>

     7.  Nothing  herein  contained  shall  affect  the  priority  of  the  Lien
Instrument,  the MWI Second Lien  Instrument and the MWII Second Lien Instrument
over other liens,  charges,  encumbrances or conveyances nor shall it release or
change the liability of any party who may now or hereafter be liable,  primarily
or secondarily, under or on account of the Note.

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<PAGE>



     IN  WITNESS  WHEREOF,  this  First  Amendment  has  been  executed  by  the
undersigned as of the date and year first above written.

                        THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY,
                        a Wisconsin corporation

                        By:  Northwestern Investment Management Company, LLC,
                             a Delaware limited liability company, its
                             wholly-owned affiliate and authorized
                             representative

                             By:      /S/ Michael P. Cusick
                                ------------------------------------------------
                                Michael P. Cusick
                                Managing Director

                             Attest:  /S/ Donna L. Lemanczyk
                                    --------------------------------------------
                                    Donna L. Lemanczyk
                                    Assistant Secretary
(corporate seal)


                        MISSION WEST PROPERTIES, L.P.,
                        a Delaware limited partnership

                        By:  Mission West Properties, Inc.,
                             a Maryland corporation,
                             its general partner

                             By:      /S/ Raymond V. Marino
                                -----------------------------------------
                             Name:     Raymond V. Marino
                                 ----------------------------------------
                             Title:   President & COO
                                   --------------------------------------




                   (Consent of Guarantor and signature follow)

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<PAGE>



         CONSENT OF GUARANTOR:


The  undersigned  guarantor,  who is a party  under that  certain  Guarantee  of
Recourse  Obligations  dated as of June 3, 2003,  joins in the execution of this
document for the purpose of acknowledging  the above. The undersigned  guarantor
confirms that, except as herein modified,  the Guarantee of Recourse Obligations
remains in full force and effect,  unchanged  and in all  respects  ratified and
confirmed.

                                   GUARANTOR:

                                   MISSION WEST PROPERTIES, INC.,
                                   A Maryland corporation

                                   By:      /S/ Raymond V. Marino
                                      ----------------------------------------
                                   Name:    Raymond V. Marino
                                        --------------------------------------
                                   Title:   President & COO
                                         -------------------------------------

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<PAGE>



                                   SCHEDULE 1

                                Promissory Notes


Promissory Note dated January 3, 2003 executed by Mission West Properties,  L.P.
in the original  principal  amount of  $28,868,655.00,  as amended by that First
Amendment To Promissory Note dated November 5, 2008 now in the principal  amount
of $49,151,169.00.

Promissory Note dated January 3, 2003 executed by Mission West Properties,  L.P.
I in the original principal amount of  $29,811,369.00,  as amended by that First
Amendment To Promissory Note dated November 5, 2008 now in the principal  amount
of $23,228,942.00.

Promissory Note dated January 3, 2003 executed by Mission West Properties,  L.P.
II in the original principal amount of $41,319,976.00,  as amended by that First
Amendment To Promissory Note dated November 5, 2008 now in the principal  amount
of $9,551,366.00.

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