<PAGE>

                    U.S. SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

                                  FORM 10-QSB
  (Mark One)

       X       QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
               SECURITIES EXCHANGE ACT OF 1934

                 For the quarterly period ended March 31, 1999
                                                --------------

                                      OR

           TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                        SECURITIES EXCHANGE ACT OF 1934

           For the transition period from ___________ to ___________

                        Commission file number 0-10404
                                               -------
                   Winthrop Partners 81 Limited Partnership
                   ----------------------------------------      
      (Exact name of small business issuer as specified in its charter)

            Massachusetts                              04-2720480         
   -------------------------------         ------------------------------------
   (State or other jurisdiction of         (I.R.S. Employer Identification No.) 
    incorporation or organization)

  Five Cambridge Center, Cambridge, MA                02142-1493                
 ---------------------------------------    -----------------------------------
 (Address of principal executive office)              (Zip Code)

      Registrant's telephone number, including area code (617) 234-3000
                                                         --------------

Indicate by check mark whether Registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934
during the preceding 12 months (or for such shorter period that the Registrant
was required to file such reports), and (2) has been subject to such filing
requirements for the past 90 days.   Yes  X     No
                                        ------     ------


                                    1 of 12

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                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP

                          FORM 10-QSB MARCH 31, 1999

                        PART 1 - FINANCIAL INFORMATION


Item 1.  Financial Statements.

Balance Sheets (Unaudited)

(In Thousands, Except Unit Data)

                                                 March 31,       December 31,
                                                   1999              1998
                                               --------------   ---------------
Assets

Real Estate Leased to Others:

Accounted for under the operating method
      and held for sale                         $         554     $         554

Other Assets:

Cash and cash equivalents                                 560               581
Other assets                                                4                 5
                                                 -------------    -------------

      Total Assets                               $      1,118     $       1,140
                                                 =============    =============

Liabilities and Partners' Capital

Liabilities:

Accounts payable and accrued expenses            $        124     $          10
Distributions payable to partners                          --               151
                                                 -------------    -------------

      Total Liabilities                                   124               161
                                                 -------------    -------------

Partners' Capital:

Limited Partners -
   Units of Limited Partnership Interest,
   $500 stated value per Unit; 
   authorized-70,010 Units;
   issued and outstanding - 25,109 Units                1,256             1,242
General Partners' Deficit                                (262)             (263)
                                                 -------------    -------------

      Total Partners' Capital                             994               979
                                                 -------------    -------------

      Total Liabilities and Partners' Capital    $      1,118     $       1,140
                                                 -------------    -------------

                      See notes to financial statements.

                                   2 of 12

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                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP

                          FORM 10-QSB MARCH 31, 1999


Statements of Income (Unaudited)

(In Thousands, Except Unit Data)


                                                  For The Three Months Ended
                                                 March 31,          March 31,
                                                   1999               1998
                                                 -----------      ----------- 
Income:

Rental income from real estate leases accounted
      for under the operating method             $        27      $         23
Interest on short-term investments                         6                 7
Interest income on real estate leases accounted           
      for under the financing method                      --                 2
                                                 -----------      ------------

         Total income                                     33                32
                                                 -----------      ------------

Expenses:

Operating                                                 --                14
General and administrative                                18                17
                                                 -----------      ------------
      
         Total expenses                                   18                31
                                                 -----------      ------------

Net income                                       $        15      $          1
                                                 ===========      ============

Net income allocated to general partners         $         1      $         --
                                                 ===========      ============

Net income allocated to limited partners         $        14      $          1
                                                 ===========      ============

Net income per Unit of Limited 
    Partnership Interest                         $      0.56      $       0.04
                                                 ===========      ============

Distributions per Unit of Limited 
    Partnership Interest                         $        --      $         --
                                                 ===========      ============


                      See notes to financial statements.

                                   3 of 12

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                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP

                          FORM 10-QSB MARCH 31, 1999


Statement of Partners' Capital (Unaudited)

(In Thousands, Except Unit Data)

<TABLE>
<CAPTION>
                                       Units of
                                       Limited                 General            Limited            Total
                                     Partnership              Partners'          Partners'          Partners'
                                      Interest                 Deficit            Capital            Capital
                                  ------------------     ---------------      ---------------    --------------
<S>                               <C>                    <C>                  <C>                <C>
Balance - January 1, 1999                  25,109        $         (263)      $         1,242     $         979
 
    Net income                                                        1                    14                15
                                  ------------------     -----------------     --------------     --------------

Balance - March 31, 1999                   25,109        $         (262)       $        1,256      $        994
                                  ==================     =================     ===============     =============
</TABLE>


                      See notes to financial statements.

                                   4 of 12
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                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP

                          FORM 10-QSB MARCH 31, 1999


Statements of Cash Flows (Unaudited)

(In Thousands)

<TABLE>
<CAPTION>
                                                                                   For The Three Months Ended
                                                                        March 31,                             March 31,
                                                                          1999                                  1998
                                                                ----------------------------          ----------------------------
<S>                                                             <C>                                    <C>
Cash Flows From Operating Activities:

Net income                                                      $                         15          $                          1
Adjustments to reconcile net income to net cash provided
  by operating activities:
      Decrease in other assets                                                             1                                    15
      Increase (decrease) in accounts payable and
        accrued expenses                                                                 114                                   (11)
                                                                ----------------------------          ----------------------------

      Net cash provided by operating activities:                                         130                                     5
                                                                ----------------------------          ----------------------------

Cash Flows From Investing Activities:

      Minimum lease payments received, net of interest
         income earned, on leases accounted for under
         the financing method                                                             --                                    2
                                                                ----------------------------          ----------------------------

      Cash provided by investing activities                                               --                                    2
                                                                ----------------------------          ----------------------------

Cash Flows From Financing Activities:

      Cash distributions                                                                (151)                                  --
                                                                ----------------------------          ----------------------------

      Cash used in financing activities                                                 (151)                                  --
                                                                ----------------------------          ----------------------------

Net (decrease) increase in cash and cash equivalents                                     (21)                                   7

Cash and cash equivalents, beginning of period                                           581                                  518
                                                                ----------------------------          ----------------------------

Cash and cash equivalents, end of period                        $                        560          $                       525
                                                                ============================          ============================
</TABLE>

                      See notes to financial statements.

                                   5 of 12
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                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP

                          FORM 10-QSB MARCH 31, 1999

                         NOTES TO FINANCIAL STATEMENTS

1.             General

               The accompanying financial statements, footnotes and
               discussions should be read in conjunction with the financial
               statements, related footnotes and discussions contained in the
               Partnership's annual report on Form 10-KSB for the year ended
               December 31, 1998.

               The financial information contained herein is unaudited. In the
               opinion of management, all adjustments necessary for a fair
               presentation of such financial information have been included.
               All adjustments are of a normal recurring nature. Certain
               reclassifications have been made to the March 31, 1998 amounts
               to conform to the March 31, 1999 presentation. The balance
               sheet at December 31, 1998 was derived from audited financial
               statements at such date.

               The results of operations for the three months ended March 31,
               1999 and 1998, are not necessarily indicative of the results to
               be expected for the full year.

2.             Contract for Sale of Property

               On April 23, 1999, the Partnership entered into a contract to 
               sell its remaining property for $1,020,000. If the sale is
               consummated, the Partnership will recognize a gain for
               financial reporting purposes of approximately $360,000 and a
               gain for tax reporting purposes of approximately $500,000.


                                    6 of 12

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                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP

                          FORM 10-QSB MARCH 31, 1999


Item 2.      Management's Discussion and Analysis or Plan of Operation

             The matters discussed in this Form 10-QSB contain certain
             forward-looking statements and involve risks and uncertainties
             (including changing market conditions, competitive and regulatory
             matters, etc.) detailed in the disclosure contained in this Form
             10-QSB and the other filings with the Securities and Exchange
             Commission made by the Partnership from time to time. The
             discussion of the Partnership's liquidity, capital resources and
             results of operations, including forward-looking statements
             pertaining to such matters, does not take into account the
             effects of any changes to the Partnership's operations.
             Accordingly, actual results could differ materially from those
             projected in the forward-looking statements as a result of a
             number of factors, including those identified herein.

             This item should be read in conjunction with the financial
             statements and other items contained elsewhere in the report.

             Liquidity and Capital Resources

             The Partnership's remaining property is a retail store, which is
             leased to a single tenant, Frank's Nursery and Crafts, Inc.
             ("Franks"), pursuant to a triple net lease. On April 23, 1999,
             the Partnership entered into a contract to sell this property for
             $1,020,000. If the sale is consummated, the Partnership will
             recognize a gain for financial reporting purposes and the
             Partnership will be liquidated. The present lease with Franks
             expires in January 2003, subject to extension. The lease was
             extended during 1998 at an increase in rent of 8%. At December
             31, 1998, the Partnership recorded an accrued distribution
             payable of $151,000. These funds were distributed in March of
             1999.

             The Partnership receives rental income from its leased property
             which is its primary source of liquidity. Pursuant to the terms
             of the lease, the tenant is responsible for substantially all of
             the operating expenses with respect to the property including
             maintenance, capital improvements, insurance and taxes.

             The level of liquidity based on cash and cash equivalents
             experienced a $21,000 decrease at March 31, 1999, as compared to
             December 31, 1998. The Partnership's $130,000 of cash provided by
             operating activities was offset by $151,000 of cash distributed
             to partners (financing activities). At March 31, 1999, the
             Partnership had approximately $560,000 in cash and cash
             equivalents which has been invested primarily in money market
             mutual funds.

             The Partnership requires cash primarily to pay general and
             administrative expenses. In addition, if the Partnership is
             unable to sell its remaining property prior to its lease
             expiration, extend the current lease or re-let the property upon
             the expiration of the lease terms, the Partnership would be
             responsible for operating expenses, such as real estate taxes,
             insurance and utility expenses associated with the property.

                                    7 of 12
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                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP

                          FORM 10-QSB MARCH 31, 1999


Item 2.      Management's Discussion and Analysis or Plan of Operation

             Year 2000

             The Year 2000 Issue is the result of computer programs being
             written using two digits rather than four to define the
             applicable year. The Registrant is dependent upon the Managing
             General Partner and its affiliates for management and
             administrative services. Any computer programs or hardware that
             have date-sensitive software or embedded chips may recognize a
             date using "00" as the year 1900 rather than the year 2000. This
             could result in system failure or miscalculations causing
             disruptions of operations, including, among other things, a
             temporary inability to process transactions, send invoices, or
             engage in similar normal business activities.

             During the first half of 1998, the Managing General Partner and
             its affiliates completed their assessment of the various computer
             software and hardware used in connection with the management of
             the Registrant. This review indicated that significantly all of
             the computer programs used by the Managing General Partner and
             its affiliates are off-the-shelf "packaged" computer programs
             which are easily upgraded to be Year 2000 compliant. In addition,
             to the extent that custom programs are utilized by the Managing
             General Partner and its affiliates, such custom programs are Year
             2000 compliant.

             Following the completion of its assessment of the computer
             software and hardware, the Managing General Partner and its
             affiliates began upgrading those systems which required
             upgrading. To date, significantly all of these systems have been
             upgraded. The Registrant has to date not borne, nor is it
             expected that the Registrant will bear, any significant costs in
             connection with the upgrade of those systems requiring
             remediation. It is expected that all systems will be remediated,
             tested and implemented during the first half of 1999.

             To date, the Managing General Partner is not aware of any
             external agent with a Year 2000 issue that would materially
             impact the Registrant's results of operations, liquidity or
             capital resources. However, the Managing General Partner has no
             means of ensuring that external agents will be Year 2000
             compliant. The Managing General Partner does not believe that the
             inability of external agents to complete their Year 2000
             resolution process in a timely manner will have a material impact
             on the financial position or results of operations of the
             Registrant. However, the effect of non-compliance by external
             agents is not readily determinable.

             Results of Operations

             Net income increased by $14,000 for the three months ended March
             31, 1999, as compared to the comparable period in 1998, primarily
             due to a decrease in expenses of $13,000 and an increase in
             income of $1,000. Expenses decreased due to the elimination of
             operating expenses from the sale of the Partnership's Columbus,
             Ohio property in May 1998.

                                    8 of 12

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                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP

                          FORM 10-QSB MARCH 31, 1999

Part II - Other Information

Item 6.    Exhibits and Reports on Form 8-K.

           (a)   Exhibits

                 27.    Financial Data Schedule

                 99.    Supplementary Information Required Pursuant to Section 
                        9.4 of the Partnership Agreement.

           (b)   Reports on Form 8-K:

                 No reports on Form 8-K were filed during the three months
                 ended March 31, 1999.



                                    9 of 12
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                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP

                          FORM 10-QSB MARCH 31, 1999
 
                                  SIGNATURES
 

Pursuant to the requirements of the Securities and Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned, thereunto duly authorized.


                            WINTHROP PARTNERS 81 LIMITED PARTNERSHIP

                            BY:    ONE WINTHROP PROPERTIES, INC.
                                   Managing General Partner



                                   BY:     /s/ Michael L. Ashner
                                           ---------------------------    
                                           Michael L. Ashner
                                           Chief Executive Officer and Director


                                   BY:     /s/ Thomas C. Staples 
                                           ---------------------------    
                                           Thomas C. Staples
                                           Chief Financial Officer



                                           Dated: May 13, 1999




                                   10 of 12
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                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP

                          FORM 10-QSB MARCH 31, 1999


 Exhibit Index


         Exhibit                                                      Page No.

 27.     Financial Data Schedule                                         --

 99.     Supplementary Information Required Pursuant to
         Section 9.4 of the Partnership Agreement.                       12






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