<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 June 30, 1998

                                      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

<PAGE>
                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP
                           FORM 10-QSB JUNE 30, 1998

                        PART 1 - FINANCIAL INFORMATION

Item 1.  Financial Statements.

Balance Sheets (Unaudited)

(In Thousands, Except Unit Data)

                                                          June 30,  December 31,
                                                            1998         1997
                                                         ---------    ---------
Assets

Real Estate:

Accounted for under the operating method,
     at cost, net of accumulated depreciation
     of $906 (1997)                                      $      -     $     752
Land                                                           409          601
Accounted for under the financing method                       145          147
                                                         ---------    ---------
                                                               554        1,500

Other Assets:

Cash and cash equivalents                                    2,406          518
Other assets                                                    24           21
                                                         ---------    ---------
         Total Assets                                    $   2,984    $   2,039
                                                         =========    =========

Liabilities and Partners' Capital

Liabilities:

Accounts payable and accrued expenses                    $       8    $      50
Distributions payable                                        1,910            -
                                                         ---------    ---------
         Total Liabilities                                   1,918           50
                                                         ---------    ---------

Partners' Capital:

Limited Partners -
   Units of Limited Partnership Interest,
   $500 stated value per Unit; authorized-70,010 Units;
   issued and outstanding - 25,109 Units                     1,334        2,268
General Partners' Deficit                                     (268)        (279)
                                                         ---------    ---------
         Total Partners' Capital                             1,066        1,989
                                                         ---------    ---------
         Total Liabilities and Partners' Capital         $   2,984    $   2,039
                                                         =========    =========


                      See notes to financial statements.

                                    2 of 12

<PAGE>
                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP
                           FORM 10-QSB JUNE 30, 1998

Statements of Income (Unaudited)

(In Thousands, Except Unit Data)

<TABLE>
<CAPTION>
                                                       For The Three Months Ended    For The Six Months Ended
                                                          June 30,     June 30,        June 30,     June 30,
                                                            1998         1997            1998         1997
                                                          -------       ------          ------       ------
<S>                                                       <C>           <C>             <C>          <C>
Income:

Rental income from real estate leases accounted
     for under the operating method                       $    13       $   32          $   25       $  106
Interest on short-term investments                             16            6              23           12
Interest income on real estate leases accounted
     for under the financing method                            14            4              27            8
Gain on sale of building                                      967           --             967           --
                                                          -------       ------          ------       ------
         Total income                                       1,010           42           1,042          126
                                                          -------       ------          ------       ------
Expenses:

Operating                                                      10           --              24           --
Depreciation                                                   --           12              --           24
Management fees                                                --            1              --            2
General and administrative                                     14           23              31           36
                                                          -------       ------          ------       ------
         Total expenses                                        24           36              55           62
                                                          -------       ------          ------       ------

Net income                                                $   986       $    6          $  987       $   64
                                                          =======       ======          ======       ======

Net income allocated to general partners                  $    11       $   --          $   11       $    5
                                                          =======       ======          ======       ======

Net income allocated to limited partners                  $   975       $    6          $  976       $   59
                                                          =======       ======          ======       ======

Net income per Unit of Limited Partnership Interest       $ 38.83       $  .24          $38.87       $ 2.35
                                                          =======       ======          ======       ======

Distributions per Unit of Limited Partnership Interest    $ 76.07       $   --          $76.07       $   --
                                                          =======       ======          ======       ======
</TABLE>


                      See notes to financial statements.

                                    3 of 12

<PAGE>

                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP
                           FORM 10-QSB JUNE 30, 1998

Statement of Partners' Capital (Unaudited)

(In Thousands, Except Unit Data)

                                   Units of
                                    Limited    General     Limited
                                  Partnership  Partners'   Partners'   Total
                                   Interest    Deficit     Capital     Capital
                                    -------    -------     -------     -------

Balance - January 1, 1998            25,109    $  (279)    $ 2,268     $ 1,989

   Net income                                       11         976         987

   Distributions                                    --      (1,910)     (1,910)
                                    -------    -------     -------     -------

Balance - June 30, 1998              25,109    $  (268)    $ 1,334     $ 1,066
                                    =======    =======     =======     =======



                      See notes to financial statements.

                                    4 of 12

<PAGE>

                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP
                           FORM 10-QSB JUNE 30, 1998

Statements of Cash Flows (Unaudited)

(In Thousands)

<TABLE>
<CAPTION>
                                                                    For The Six Months Ended
                                                                     June 30,       June 30,
                                                                       1998           1997
                                                                     -------        -------
<S>                                                                  <C>            <C>
Cash Flows From Operating Activities:

Net income                                                           $   987        $    64
Adjustments to reconcile net income to net cash
  (used in) provided by operating activities:
     Depreciation                                                         --             24
     Gain on sale of building                                           (967)            --

Changes in assets and liabilities:
     (Increase) decrease in other assets                                  (3)             2
     Decrease in accounts payable and
       accrued expenses                                                  (42)           (22)
                                                                     -------        -------

Net cash (used in) provided by operating activities:                     (25)            68
                                                                     -------        -------

Cash Flows From Investing Activities:

     Minimum lease payments received, net of interest
        income earned, on leases accounted for under
        the financing method                                               3             19
     Net proceeds from sale of property                                1,910             --
                                                                     -------        -------

     Cash provided by investing activities                             1,913             19
                                                                     -------        -------

Net increase in cash and cash equivalents                              1,888             87

Cash and cash equivalents, beginning of period                           518            419
                                                                     -------        -------

Cash and cash equivalents, end of period                             $ 2,406        $   506
                                                                     =======        =======

Supplemental Disclosure of Non-Cash Financing Activities
     Accrued Distribution to Partners                                $ 1,910        $    --
                                                                     =======        =======
</TABLE>

                      See notes to financial statements.

                                    5 of 12

<PAGE>

                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP
                           FORM 10-QSB JUNE 30, 1998

                         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, 1997.

     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, except as
     discussed in Note 3, are of a normal recurring nature. The balance sheet
     at December 31, 1997, was derived from audited financial statements at
     such date.

     The results of operations for the six months ended June 30, 1998 and
     1997, are not indicative of the results to be expected for the full year.

2.   Related Party Transactions

     Management fees paid or accrued by the Partnership to an affiliate of the
     Managing General Partner, totaled $2,000 for the six months ended June
     30, 1997.

3.   Sale of Property

     On May 21, 1998, the Partnership sold its Columbus, Ohio property
     (formerly leased to GTE North Incorporated) for $1,910,000 (net of
     closing costs of $93,000), resulting in a gain of $967,000.


                                    6 of 12

<PAGE>


                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP
                           FORM 10-QSB JUNE 30, 1998

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 pursuant to a triple net lease. The
          Partnership is currently marketing its remaining property for sale.
          If the Partnership is successful in obtaining a purchaser, the
          Partnership will be liquidated. The recently extended lease with
          Frank's Nursery and Crafts, Inc. expires in January 2003, subject to
          extension. The lease was extended at a small increase in rent. On
          May 21, 1998, the Partnership sold its Columbus, Ohio [formerly
          leased to GTE North Incorporated (the "GTE Lease")] property for
          $1,910,000 (net of closing costs of $93,000) resulting in a gain of
          $967,000 for financial reporting purposes. The Partnership expects
          to distribute the net sale proceeds of $1,910,000 ($76.07 per Unit)
          during August 1998 and has made no other distributions during each
          of the six months ended June 30, 1998 and 1997.

          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
          Partnership would be responsible for similar expenses if the
          property were not re-let upon the expiration of such lease.

          The level of liquidity based on cash and cash equivalents
          experienced a $1,888,000 increase at June 30, 1998, as compared to
          December 31, 1997, due to $1,910,000 of proceeds received on the
          sale of the Partnership's Columbus, Ohio property. At June 30, 1998,
          the Partnership had approximately $2,406,000 in cash and cash
          equivalents which has been invested primarily in money market mutual
          funds.

                                    7 of 12

<PAGE>

                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP
                           FORM 10-QSB JUNE 30, 1998

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

          Liquidity and Capital Resources (Continued)

          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.

          Results of Operations

          Net income increased by $923,000 for the six months ended June 30,
          1998, as compared to 1997, due to the gain of $967,000 on sale of
          the Columbus, Ohio property.

          Revenues, excluding the gain on sale, decreased for the six months
          ended June 30, 1998, as compared to 1997, primarily due to the
          expiration of the GTE lease in April 1997. Interest on short-term
          investments increased due to the net proceeds received from the sale
          of the property. Expenses declined by $7,000, due to decreases in
          depreciation expense of $24,000 and general and administrative
          expense of $5,000, which were only partially offset by $24,000 of
          operating costs associated with the Columbus, Ohio property, which
          was vacant prior to its sale.

                                    8 of 12

<PAGE>

                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP
                           FORM 10-QSB JUNE 30, 1998

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 June 30, 1998.


                                    9 of 12

<PAGE>

                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP
                           FORM 10-QSB JUNE 30, 1998


                                  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/ Edward V. Williams
                                   ----------------------------
                                   Edward V. Williams
                                   Chief Financial Officer


                                   Dated: August 5, 1998



                                   10 of 12

<PAGE>

                   WINTHROP PARTNERS 81 LIMITED PARTNERSHIP
                           FORM 10-QSB JUNE 30, 1998

Exhibit Index

         Exhibit                                                  Page No.
         -------                                                  --------

27.      Financial Data Schedule                                      -

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




                                   11 of 12