EXHIBIT 99.1


                                                                   Press Release

For Immediate News Release
May 1, 2006


     Mission West Properties Announces First Quarter 2006 Operating Results

  "We build the buildings for the high tech companies that build the internet"


Cupertino,  CA - Mission West Properties,  Inc.  (AMEX/PCX:  MSW) reported today
that Funds From  Operations  ("FFO")  for the  quarter  ended March 31, 2006 was
$34,526,000 or $0.33 per diluted common share  (considering the potential effect
of all O.P. units being  exchanged for shares of the Company's  common stock) as
compared to $20,308,000 or $0.19 per diluted common share for the same period in
2005. On a sequential  quarter  basis,  FFO per diluted  common share  increased
$0.15  compared to the prior quarter ended December 31, 2005.  Termination  fees
and security deposit  forfeitures  relating to lease terminations  accounted for
approximately  $16,056,000,   or  $0.15  per  diluted  common  share.  Excluding
termination  fees and security  deposit  forfeitures,  FFO for the quarter ended
March 31, 2006 was $0.18 per diluted common share.

Net income to common  stockholders  per diluted  share was $0.28 for the quarter
ended March 31, 2006  compared  to $0.13 for the quarter  ended March 31,  2005.
Excluding  termination fees and security deposit  forfeitures  relating to lease
terminations,  net  income  to common  stockholders  per  diluted  share for the
quarter  ended March 31, 2006 was $0.13 per diluted  share.  The impact of stock
option  compensation  expense from the  adoption of SFAS No. 123R,  "Share-based
Payment",  had minimal impact on the Company's financial position and results of
operations.

ACQUISITION ACTIVITY

In March 2006,  the Company  acquired a fully leased  office/R&D  property  with
approximately 95,700 rentable square feet located at 233 South Hillview Drive in
Milpitas,  California from Sipex  Corporation.  The total  acquisition price for
this  property was  approximately  $13,450,000  and was funded from the proceeds
received from the 800 Embedded Way property sale in October 2005.

COMPANY PROFILE

Mission West Properties, Inc. operates as a self-managed,  self-administered and
fully integrated REIT engaged in the management, leasing, marketing, development
and acquisition of commercial R&D properties,  primarily  located in the Silicon
Valley portion of the San Francisco Bay Area. Currently, the Company manages 109
properties  totaling   approximately  7.9  million  rentable  square  feet.  For
additional information, please contact Investor Relations at 408-725-0700.

The matters described herein contain forward-looking statements. Such statements
can be  identified  by the use of  forward-looking  terminology  such as "will",
"anticipate", "estimate", "expect", "intends", or similar words. Forward-looking
statements involve a number of risks,  uncertainties or other factors beyond the
Company's  control,  which may cause  material  differences  in actual  results,
performance or other  expectations.  These factors include,  but are not limited
to, the ability to complete  acquisitions  under the Berg Land  Holdings  Option
Agreement  with the Berg  Group  and other  factors  detailed  in the  Company's
registration  statements,  and periodic  filings with the  Securities & Exchange
Commission.

                                     - 3 -


                          MISSION WEST PROPERTIES, INC.
                             SELECTED FINANCIAL DATA
        (In thousands, except share, per share and property data amounts)





                                                   Three Months        Three Months
                                                      Ended               Ended
                                                   Mar 31, 2006        Mar 31, 2005
                                                 -----------------    ---------------
REVENUES
                                                                 
Rental revenue from real estate                     $24,316 (1)          $26,247 (1)
Tenant reimbursements                                 3,309                3,628
Other income, including lease terminations
     and interest                                    16,788                  303
                                                 -----------------    ---------------
  Total revenues                                     44,413               30,178
                                                 -----------------    ---------------
EXPENSES:
Operating expenses                                    2,056                2,173
Real estate taxes                                     2,625                2,716
Interest                                              5,215                4,647
Interest (related parties)                              192                  307
General and administrative                              635                  675
Depreciation and amortization of real estate          5,479 (2)            5,574 (2)
                                                 -----------------    ---------------
  Total expenses                                     16,202               16,092
                                                 -----------------    ---------------
Income before equity in earnings of unconsolidated
     joint venture and minority interests            28,211               14,086
Equity in earnings of unconsolidated joint venture      331                   (6)
Minority interests                                  (23,390)             (11,677)
                                                 -----------------    ---------------
   Income from continuing operations                  5,152                2,403
                                                 -----------------    ---------------

Discontinued operations, net of minority interests:
  Gain from disposal of discontinued operations           -                   14
  Loss from discontinued operations                       -                   (9)
                                                 -----------------    ---------------
Income from discontinued operations                       -                    5
                                                 -----------------    ---------------
Net income to common stockholders                    $5,152               $2,408
                                                 =================    ===============
Net income to minority interests                    $23,390              $11,695
                                                 =================    ===============
Income per share from continuing operations:
   Basic                                              $0.28                $0.13
   Diluted                                            $0.28                $0.13
Income per share from discontinued operations:
   Basic                                                  -                    -
   Diluted                                                -                    -
                                                 -----------------    ---------------
Net income per share to common stockholders:
   Basic                                              $0.28                $0.13
                                                 =================    ===============
   Diluted                                            $0.28                $0.13
                                                 =================    ===============
Weighted average shares of common stock (basic)    18,455,897           18,110,524
                                                 =================    ===============
Weighted average shares of common stock (diluted)  18,520,297           18,136,797
                                                 =================    ===============
Weighted average O.P. units outstanding            86,082,539           86,371,362
                                                 =================    ===============

FUNDS FROM OPERATIONS
Funds from operations                               $34,526              $20,308
                                                 =================    ===============
Funds from operations per share ((3))                $ 0.33               $ 0.19
                                                 =================    ===============
Outstanding common stock                           18,511,291          18,147,191
                                                 =================    ===============
Outstanding O.P. units                             86,038,095          86,334,695
                                                 =================    ===============
Weighted average O.P. units and common stock
   outstanding (diluted)                          104,602,836         104,508,159
                                                 =================    ===============


                                     - 4 -





                                                   Three Months        Three Months
FUNDS FROM OPERATIONS CALCULATION                     Ended               Ended
                                                   Mar 31, 2006        Mar 31, 2005
                                                 -----------------    ---------------
                                                                  
Net income                                           $5,152               $2,408
Add:
   Minority interests ((4))                          23,256               11,574
   Depreciation and amortization of real estate
      from continuing operations                      5,907                6,001
   Depreciation and amortization of real estate
      from discontinued operations                        -                   33
   Depreciation & amortization of real estate
      held in unconsolidated joint venture              211                  355
Less:
   Gain on sale of real estate                            -                  (63)
                                                 -----------------    ---------------
Funds from operations                               $34,526              $20,308
                                                 =================    ===============


Funds From Operations ("FFO") is a non-GAAP  financial  measurement used by real
estate investment trusts ("REITs") to measure and compare operating performance.
As defined by NAREIT,  FFO represents net income (loss) before minority interest
of unit  holders  (computed  in  accordance  with  GAAP,  accounting  principles
generally accepted in the United States of America), excluding gains (or losses)
from  debt  restructuring  and  sales of  property,  plus  real  estate  related
depreciation  and  amortization  (excluding  amortization of deferred  financing
costs and  depreciation  of non-real  estate assets) and after  adjustments  for
unconsolidated  partnerships and joint ventures.  Management considers FFO to be
an  appropriate  supplemental  measure of the Company's  operating and financial
performance  because  when  compared  year over year,  it reflects the impact to
operations  from trends in  occupancy  rates,  rental  rates,  operating  costs,
general and administrative  expenses and interest costs, providing a perspective
not immediately apparent from net income. In addition,  management believes that
FFO provides useful information about the Company's  financial  performance when
compared  to other  REITs  since FFO is  generally  recognized  as the  industry
standard for reporting the operations of REITs.  FFO should not be considered as
an alternative for net income as a measure of  profitability or is it comparable
to cash flows  provided by operating  activities  determined in accordance  with
GAAP. FFO is not comparable to similarly  entitled items reported by other REITs
that do not define them exactly as we define FFO.



                                                   Three Months        Three Months
                                                       Ended              Ended
PROPERTY AND OTHER DATA:                           Mar 31, 2006        Mar 31, 2005
                                                 -----------------    ---------------
                                                                  
Total properties, end of period                          109                  108
Total square feet, end of period                   7,894,355            8,019,082
Average monthly rental revenue per square foot (5)     $1.63                $1.59

Occupancy for leased properties                         67.3%                67.7%
Straight-line rent                                  ($   677)             $   615
Leasing commissions                                  $   270              $ 3,584
Capital expenditures                                 $    79              $   285



                                     - 5 -





BALANCE SHEET                                   March 31, 2006       December 31, 2005
                                              --------------------  --------------------
Assets:
                                                                 
Land                                              $  277,269            $  273,933
Buildings and improvements                           775,237               766,457
Real estate related intangible assets                 18,784                17,410
                                              --------------------  --------------------
   Total investments in properties                 1,071,290             1,057,800
Less accumulated depreciation and amortization      (136,370)             (130,419)
                                              --------------------  --------------------
   Net investments in properties                     934,920               927,381
Cash and cash equivalents                             39,937                31,441
Restricted cash                                       12,698                16,712
Deferred rent receivable                              18,540                19,218
Investment in unconsolidated joint venture             3,340                 3,263
Other assets                                          28,212                25,362
                                              --------------------  --------------------
   Total assets                                   $1,037,647            $1,023,377
                                              ====================  ====================

Liabilities:
Mortgage notes payable                             $ 355,009             $ 357,481
Mortgage notes payable - related parties               9,955                10,051
Interest payable                                         321                   321
Security deposits                                      6,608                 8,047
Deferred rental income                                10,585                 6,103
Dividend/distribution payable                         16,729                16,725
Accounts payable and accrued expenses                 10,939                 8,952
                                              --------------------  --------------------
   Total liabilities                                 410,146               407,680

Minority interests                                   509,522               500,682

Stockholders' equity:
Common stock, $.001 par value                             18                    18
Paid in capital                                      138,811               138,038
Accumulated deficit                                  (20,850)              (23,041)
                                              --------------------  --------------------
   Total stockholders' equity                        117,979               115,015
                                              --------------------  --------------------
   Total liabilities and stockholders' equity     $1,037,647            $1,023,377
                                              ====================  ====================



(1)  Includes  approximately  $472 in amortization  expense for the three months
     ended March 31, 2006 and 2005 for the amortization of an above-market lease
     intangible asset pursuant to Statement of Financial Accounting Standard No.
     141, "Business Combinations."

(2)  Includes  approximately $340 and $440 in amortization expense for the three
     months ended March 31, 2006 and 2005, respectively, for the amortization of
     in-place  lease value  intangible  asset pursuant to Statement of Financial
     Accounting Standard No. 141, "Business Combinations."

(3)  Calculated  on a fully diluted  basis.  Assumes  conversion  of O.P.  units
     outstanding into the Company's common stock.

(4)  The  minority  interest  for third  parties  has been  deducted  from total
     minority interest in calculating FFO.

(5)  Average  monthly  rental  revenue  per square foot has been  determined  by
     taking the cash base rent for the period divided by the number of months in
     the period,  and then  divided by the average  occupied  square feet in the
     period.