EXHIBIT 12.1

                                              SENIOR HOUSING PROPERTIES TRUST
                                     COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES
                                                  (Dollars in thousands)

                                                                         Year Ended December 31,
                                                 ------------------------------------------------------------------------
                                                     2000           1999            1998           1997          1996
                                                 ------------------------------------------------------------------------
                                                                                                 

  Earnings:
  Income before gain on sale of
     properties                                       $31,022         $14,834         $46,236        $44,723      $36,441
  Fixed charges                                        15,366          18,768          19,293         16,958       14,719
                                                 ------------------------------------------------------------------------
  Adjusted Earnings                                   $46,388         $33,602         $65,529        $61,681      $51,160
                                                 ========================================================================

  Fixed Charges:
  Interest expense                                    $15,366         $18,768         $19,293        $16,958      $14,719
                                                 ------------------------------------------------------------------------
  Total Fixed Charges                                 $15,366         $18,768         $19,293        $16,958      $14,719
                                                 ========================================================================

  Ratio of Earnings to Fixed Charges                     3.0x            1.8x            3.4x           3.6x         3.5x
                                                 ========================================================================


     Senior  Housing  Properties  Trust  ("Senior  Housing"),  was  organized on
December 16, 1998, as a 100% owned subsidiary of HRPT Properties Trust ("HRPT").
On October 12, 1999, HRPT  distributed  50.7% of its ownership in Senior Housing
to HRPT  shareholders  (the  "Spin-Off").  This computation of earnings to fixed
charges is presented as if Senior  Housing was a separate legal entity from HRPT
prior to the Spin-Off,  although no such entity  existed until October 12, 1999.
Interest expense was allocated based on HRPT's historical  interest expense as a
percentage of HRPT's average historical costs of real estate investments.

     The ratios of earnings to fixed  charges  presented  above were computed by
dividing Senior Housing's earnings by fixed charges. For this purpose,  earnings
have been  calculated  by adding fixed  charges to income  before  income taxes,
extraordinary items and gain or loss on the disposition of real property.  Fixed
charges consist of interest  costs,  whether  expensed or  capitalized,  and any
interest component of capitalized lease expense,  amortization of debt discounts
and deferred  financing  costs,  whether  expensed or capitalized.  As of May 7,
2001,  Senior Housing has not issued any preferred  shares,  and so the ratio of
earnings to combined fixed charges and preferred  shares  distributions  are the
same as the ratios of earnings to fixed charges presented above.