GUARANTY


TO:   The Prudential Insurance Company of America
      Four Embarcadero Center
      Suite 2700
      San Francisco, California  94111

      The undersigned,  ___________________, a _______________ ("Guarantor"), is
a limited  partner in Mission West  Properties  L.P. [ __________  ], a Delaware
limited  partnership (the  "Partnership"),  which is a joint and several obligor
with respect to a  $130,000,000  loan from The Prudential  Insurance  Company of
America, a New Jersey corporation ("Lender"),  pursuant to which the Partnership
on September 22, 1998 has executed and delivered a promissory note (the "Note")
in  the  original  principal  amount  of  One  Hundred  Thirty  Million  Dollars
($130,000,000)  and a Deed of Trust,  Security Agreement and Fixture Filing with
Assignment of Rents and Proceeds (the "Deed of Trust").  The Note is secured and
cross-collateralized   by  certain  properties  of  the  Partnership  and  three
affiliated  limited  partnerships  whose sole  general  partner is Mission  West
Properties,  a  California  corporation,  pursuant  to the  terms of the Deed of
Trust. Loan proceeds of $________________ have been allocated to the Partnership
under the loan terms (the "Partnership  Principal") which are substantially less
than the  value of the  properties  of the  Partnership  secured  by the Deed of
Trust.

      Generally  the terms of the Note and Deed of Trust provide that no partner
in the  Partnership  shall have any personal  liability with respect to the Note
except as  provided  in  Paragraphs  18(b) and (c) of the Note or as provided in
this  Guaranty  when  executed  and  delivered  by a limited  partner to Lender.
Guarantor is providing  this  Guaranty in  connection  with the loan pursuant to
Paragraph 18(b)(i) of the Note.

      1. ACKNOWLEDGMENT.  Guarantor hereby acknowledges that the Partnership has
obtained the  aforementioned  loan from  Lender;  and that the  Partnership  has
executed  and  delivered  the Note and Deed of Trust to  Lender;  and  Guarantor
hereby affirms and approves the same.

      2. AMOUNT OF GUARANTY. Guarantor shall be obligated to pay Lender pursuant
to this Guaranty no more than that amount of the original  principal of the Note
which is provided under this paragraph (the "Guaranteed  Amount")  together with
accrued  and  unpaid  interest  thereon.   The  initial   Guaranteed  Amount  is
____________  _______________________  ($_____________).  The Guaranteed  Amount
shall be reduced simultaneously with each payment by the Partnership of original
principal  under the terms of the Note by an amount  equal to  ________  percent
(__%) of each  such  payment,  which is the same  percentage  as the  Guaranteed
Amount bears to the total original  principal  amount of  Partnership  Principal
that has been guaranteed by limited partners of the  Partnership.  THIS GUARANTY
DOES NOT OBLIGATE THE  GUARANTOR  FOR ANY  EXISTING OR  CONTINGENT  LIABILITY OR
OTHER  OBLIGATION OF THE  PARTNERSHIP  UNDERTAKEN IN CONNECTION WITH THE NOTE OR
DEED OF TRUST EXCEPT FOR THE GUARANTEED AMOUNT.

      3. CONDITIONS TO GUARANTY. Guarantor shall not be liable for any amount to
Lender  pursuant to this Guaranty  unless all of the following  conditions  have
been  satisfied  first:  (a) there exists an event of default under the terms of
the Note or Deed of Trust, (b) Lender has accelerated the payment of the Note in
accordance  with the terms of the Note and Deed of Trust,  (c) Lender has made a
demand on the  Partnership  for payment of all amounts  then due under the Note,
(d) the  Partnership has failed or refused to satisfy all amounts then due under
the Note , (e) Lender has exercised  all of its rights to the  collateral of the
Partnership  securing the Note and has disposed of such collateral in accordance
with the terms of the Note, Deed of Trust and other  agreements  respecting such
collateral,  (f) there remains  unpaid  principal and interest on the Note after
Lender has exhausted its rights with respect to the collateral securing the Note
(including,  but not limited  to,  after  taking into  account the amount of any
indebtedness  owing  under the Note  applied  toward  Lender's  purchase  of any
property  securing  the Note  pursuant  to a judicial  foreclosure,  nonjudicial
foreclosure, or otherwise), (g) the Lender has exhausted all of its remedies and
recourse to all other  assets of the  Partnership,  and (h) Lender has  demanded
payment  from  Guarantor  pursuant to written  notice  specifying  the amount of
principal under the Note then subject to this Guaranty,  which shall in no event
exceed the Guaranteed Amount, and delivered to Guarantor's  address as set forth
in the records of the Partnership.

      4.  Guarantor  hereby waives notice of  acceptance  hereof,  of any action
taken or omitted in reliance  hereon,  and of any defaults of the Partnership in
the payment of any such sums or in the  performance  of any such  covenants  and
agreements.  Guarantor  hereby  agrees that none of the  following  shall in any
manner  release,  affect or impair its liability  under this Guaranty or require
its consent  thereto:  (a) any amendment or  modification of the Note or Deed of
Trust issued thereunder,  including the renewal or extension of any of the Note,
(b) any failure to realize  proceeds from the sale of any property  securing the
Note provided that any such sale is effected in accordance with the terms of the
agreements regarding Lender's security interest in such property.


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                             GUARANTY SIGNATURE PAGE


      5. This Guaranty  shall be governed by the laws of the State of California
without regard to principles concerning the conflict of laws.

      IN WITNESS  WHEREOF,  the  undersigned  has executed  this  Guaranty as of
September __, 1998.
                                    GUARANTOR


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                          By:  [ _______________________________
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