<PAGE>

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                    FORM 10-Q


                                   (MARK ONE)


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


                     FOR THE PERIOD ENDED SEPTEMBER 30, 2000

                                       OR

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


                         COMMISSION FILE NUMBER: 0-28324


                           BIOTRANSPLANT INCORPORATED
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)


                DELAWARE                                     04-3119555
     (STATE OR OTHER JURISDICTION OF                     (I.R.S. EMPLOYER
     INCORPORATION OR ORGANIZATION)                     IDENTIFICATION NO.)


                CHARLESTOWN NAVY YARD, BUILDING 75, THIRD AVENUE
                        CHARLESTOWN, MASSACHUSETTS 02129
                    (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)


                                 (617) 241-5200
              (REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE)


     Indicate by check mark whether the 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 / /

     As of November 3, 2000 there were 11,767,562 shares of the Registrant's
Common Stock outstanding.
<PAGE>

                    BIOTRANSPLANT INCORPORATED AND SUBSIDIARY
                                    FORM 10-Q
                                      INDEX

                          PART I. FINANCIAL INFORMATION

<TABLE>
<CAPTION>
                                                                                Page No.
                                                                                --------
<S>                                                                             <C>
ITEM 1.  CONDENSED CONSOLIDATED FINANCIAL STATEMENTS:

       Condensed Consolidated Balance Sheets as of December 31, 1999 and
          September 30, 2000 ...................................................     3

       Condensed Consolidated Statements of Operations for the three and
          nine months ended September 30, 1999 and 2000, and for the period
          from inception (March 20, 1990) to September 30, 2000 ................     4

       Condensed Consolidated Statements of Cash Flows for the nine months
          ended September 30, 1999 and 2000, and for the period from inception
          (March 20, 1990) to September 30, 2000 ...............................     5

       Notes to Condensed Consolidated Financial Statements ....................     6

ITEM 2. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION
   AND RESULTS OF OPERATIONS ...................................................     8

ITEM 3. QUANTITIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISKS ..............    11

                           PART II. OTHER INFORMATION

ITEM 1. - 6. ...................................................................    12

SIGNATURES .....................................................................    13

</TABLE>

                                        2

<PAGE>

PART I. FINANCIAL INFORMATION
ITEM 1. CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

                    BIOTRANSPLANT INCORPORATED AND SUBSIDIARY
                          (A DEVELOPMENT STAGE COMPANY)

                      CONDENSED CONSOLIDATED BALANCE SHEETS

<TABLE>
<CAPTION>
                                                                            September 30,
                                                          December 31,          2000
                                                             1999           (Unaudited)
                                                         ------------       ------------
<S>                                                      <C>                <C>
ASSETS
Current assets:
     Cash and cash equivalents                           $ 17,648,789         14,517,476
     Short-term investments                                 3,718,033          4,863,052
     Accounts receivable                                      400,500            287,247
     Prepaid expenses and other current assets                169,733            225,046
                                                         ------------       ------------
         Total current assets                              21,937,055         19,892,821
                                                         ------------       ------------
Property and equipment - net                                1,482,000          1,316,161
                                                         ------------       ------------
TOTAL ASSETS                                             $ 23,419,055       $ 21,208,982
                                                         ============       ============

LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities:
     Current portion of long-term debt                   $    233,333       $    233,333
     Accounts payable                                         433,067            326,566
     Accrued expenses                                       2,516,173          2,333,780
     Deferred revenue                                       4,125,000                 --
                                                         ------------       ------------
         Total current liabilities                          7,307,573          2,893,679
                                                         ------------       ------------
     Long-term debt, net of current portion                   466,667            305,303
                                                         ------------       ------------
Stockholders' equity:
     Preferred stock, $.01 par value,
         authorized - 2,000,000 shares;
         issued and outstanding - no shares                        --                 --
     Common stock, $.01 par value,
         authorized - 25,000,000 shares at
         December 31, 1999 and 50,000,000 at
         September 30, 2000;  issued and
         outstanding - 10,300,890  shares
         at December 31, 1999 and 11,717,430 shares
         at September 30, 2000                                103,010            117,058
     Additional paid-in capital                            72,688,036         82,446,820
     Accumulated deficit                                  (57,146,231)       (64,553,878)
                                                         ------------       ------------
         Total stockholders' equity                        15,644,815         18,010,000
                                                         ------------       ------------
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY               $ 23,419,055       $ 21,208,982
                                                         ============       ============

</TABLE>

              The accompanying notes are an integral part of these
                  condensed consolidated financial statements.

                                      3

<PAGE>

                    BIOTRANSPLANT INCORPORATED AND SUBSIDIARY
                          (A DEVELOPMENT STAGE COMPANY)

                 CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
                                   (UNAUDITED)

<TABLE>
<CAPTION>
                                           Three Months Ended                     Nine Months Ended                 Cumulative
                                              September 30,                         September 30,                      Since
                                        1999               2000                1999                2000              Inception
                                   -------------       -------------       -------------       -------------       -------------
<S>                                <C>                 <C>                 <C>                 <C>                 <C>
Revenues:
   License fees                    $   2,500,000       $          --       $   2,500,000       $          --       $  18,500,000
   Research and development            1,234,619           1,476,880           3,711,619           4,453,880          36,705,855
   Interest income                       160,789             348,327             559,695           1,048,358           6,701,197
                                   -------------       -------------       -------------       -------------       -------------
        Total revenues                 3,895,408           1,825,207           6,771,314           5,502,238          61,907,052
                                   -------------       -------------       -------------       -------------       -------------

Expenses:
   Research and development            3,812,515           3,645,493          11,432,747          10,970,524         103,912,082
   General and administrative            683,940             664,673           1,797,677           1,892,708          20,724,703
   Interest                                  485              15,483               1,815              46,653           1,824,145
                                   -------------       -------------       -------------       -------------       -------------
        Total expenses                 4,496,940           4,325,649          13,232,239          12,909,885         126,460,930
                                   -------------       -------------       -------------       -------------       -------------
Net loss                           $    (601,532)      $  (2,500,442)      $  (6,460,925)      $  (7,407,647)      $ (64,553,878)
                                   =============       =============       =============       =============       =============
Basic and diluted net loss
   per common share                $       (0.07)      $       (0.21)      $       (0.75)      $       (0.65)
                                   =============       =============       =============       =============
Weighted average common
   shares outstanding                  8,583,844          11,708,920           8,583,351          11,470,249
                                   =============       =============       =============       =============

</TABLE>

              The accompanying notes are an integral part of these
                  condensed consolidated financial statements.

                                        4
<PAGE>

                    BIOTRANSPLANT INCORPORATED AND SUBSIDIARY
                          (A DEVELOPMENT STAGE COMPANY)

                 CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
                                   (UNAUDITED)

<TABLE>
<CAPTION>
                                                                                 Nine Months Ended                Cumulative
                                                                                   September 30,                    Since
                                                                               1999               2000            Inception
                                                                           ------------       ------------       ------------
<S>                                                                        <C>                <C>                <C>
Cash flows from operating activities:
     Net loss                                                              $ (6,460,925)      $ (7,407,647)      $(64,553,878)
     Adjustments to reconcile net loss to net cash used in
        operating activities:
         Depreciation and amortization                                          292,584            311,672          4,188,816
         Noncash interest expense                                                    --                 --            465,477
         Noncash expenses related to options and warrants                            --                 --          1,186,787
         Changes in current assets and liabilities:
              Accounts receivable                                                                 (298,585)          (287,247)
              Deposits and prepaid expenses                                     759,721            356,525           (225,046)
              Accounts payable                                                  (62,299)          (106,501)           326,566
              Accrued expenses                                                  715,604           (182,392)         2,333,780
              Deferred revenue                                                3,226,856         (4,125,000)
                                                                           ------------       ------------       ------------
         Net cash used in operating activities                               (1,528,459)       (11,451,928)       (56,564,745)
                                                                           ------------       ------------       ------------
Cash flows from investing activities:
     Purchases of property and equipment                                       (294,442)          (145,834)        (4,881,782)
     Disposal of property and equipment, net                                         --                 --             28,040
     Purchases of short-term investments                                       (404,136)        (6,461,733)       (76,686,130)
     Proceeds from short-term investments                                     7,247,099          5,316,713         71,823,076
                                                                           ------------       ------------       ------------
         Net cash provided by (used in) investing activities                  6,548,521         (1,290,854)        (9,716,796)
                                                                           ------------       ------------       ------------
Cash flows from financing activities:
     Proceeds from convertible notes payable to stockholders                         --                 --          9,400,000
     Payments of long-term debt                                                      --           (161,364)          (161,364)
     Payments of obligations under capital leases                                (8,980)                           (2,194,210)
     Proceeds from sale/leaseback of equipment                                       --                 --            771,968
     Net proceeds from equipment leases                                              --                 --          1,422,240
     Net proceeds from long-term debt                                           700,000                               700,000
     Net proceeds from sale of redeemable convertible preferred stock                --                 --         25,661,526
     Proceeds from sale of common stock                                           7,975          9,772,833         45,198,857
                                                                           ------------       ------------       ------------
         Net cash provided by (used in) financing activities                   (698,995)         9,611,469         80,799,017
                                                                           ------------       ------------       ------------
Net increase (decrease) in cash and cash equivalents                         (5,719,057)        (3,131,313)        14,517,476

Cash and cash equivalents, beginning of period                               13,168,496         17,648,789                 --
                                                                           ------------       ------------       ------------
Cash and cash equivalents, end of period                                   $ 18,887,553       $ 14,517,476       $ 14,517,476
                                                                           ============       ============       ============
Supplemental disclosures and noncash transactions:
     Equipment acquired under capital leases                               $         --       $         --       $  2,210,270
                                                                           ============       ============       ============
     Conversion of convertible notes payable to stockholders and
         accrued interest into redeemable convertible preferred stock      $         --       $         --       $  9,905,710
                                                                           ============       ============       ============
     Conversion of preferred stock into common stock                       $         --       $         --       $ 36,202,290
                                                                           ============       ============       ============
     Issuance of warrants                                                  $         --       $         --       $    741,737
                                                                           ============       ============       ============
     Interest paid during the period                                       $      1,745       $     43,504       $  1,453,559
                                                                           ============       ============       ============
</TABLE>

              The accompanying notes are an integral part of these
                  condensed consolidated financial statements.

                                        5
<PAGE>

                    BIOTRANSPLANT INCORPORATED AND SUBSIDIARY
                          (A DEVELOPMENT STAGE COMPANY)

              NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
                                   (UNAUDITED)


1.   OPERATIONS AND BASIS OF PRESENTATION

BioTransplant Incorporated and subsidiary (the "Company") was incorporated on
March 20, 1990. The Company utilizes its proprietary technologies in
re-educating the body's immune responses to allow tolerance of foreign cells,
tissues and organs. Based on this technology, which the Company refers to as
ImmunoCognance-TM-, the Company is developing a portfolio of products
designed to treat a range of medical conditions for which current therapies
are inadequate, including organ and tissue transplantation, cancer and
autoimmune disease. BioTransplant's products under development are intended
to induce long-term functional transplantation tolerance in humans, increase
the therapeutic benefit of bone marrow transplants, and reduce or eliminate
the need for lifelong immunosuppresive therapy.

The Company is in the development stage and is devoting substantially all of its
efforts toward product research and development and raising capital. The Company
is subject to a number of risks similar to those of other development stage
companies, including dependence on key individuals and collaborative partners,
competition from larger companies, the Company's ability to develop commercially
usable products, and to obtain and maintain regulatory approval for products
under development, and the Company's ability to obtain adequate additional
financing necessary to fund the development of its products.

The interim financial statements herein have been prepared by the Company,
without audit, pursuant to the rules and regulations of the Securities and
Exchange Commission ("SEC") and include, in the opinion of management, all
adjustments, consisting of normal, recurring adjustments, necessary for a fair
representation of interim period results. Certain information and footnote
disclosures normally included in financial statements prepared in accordance
with generally accepted accounting principles have been condensed or omitted
pursuant to such rules and regulations. The results for the interim periods
presented are not necessarily indicative of results to be expected for the
fiscal year or any future period. These condensed consolidated financial
statements should be read in conjunction with the audited consolidated financial
statements and the notes thereto included in the Company's Annual Report on Form
10-K for the year ended December 31, 1999, as filed with the SEC.

2.   CASH EQUIVALENTS AND INVESTMENTS

Cash equivalents include short-term, highly liquid investments with original
maturities of less than ninety days from the date of purchase. Short-term
investments consist primarily of corporate notes and securities issued by the
United States Treasury or other United States government agencies with original
maturities of greater than three months and remaining maturities of less than
one year. In accordance with Financial Accounting Standards Board Statement No.
115, "Accounting for Certain Investments in Debt and Equity Securities", the
Company's investments are classified as held-to-maturity and are stated at
amortized cost, which approximates market value.

The Company held the following investments at December 31, 1999 and September
30, 2000:

<TABLE>
<CAPTION>
                                                       December 31,     September 30,
                                                           1999            2000
                                                       -----------      -----------
<S>                                                    <C>              <C>
Cash and cash equivalents                              $17,648,789      $14,517,746
                                                       -----------      -----------
Short-term Investments
  Corporate Bonds (average maturity of 4 months)                --      $ 2,399,662
  Commercial Paper (average maturity of 3 months)      $ 3,718,033        2,463,390
                                                       -----------      -----------

Total cash and cash equivalents and investments        $21,366,822      $19,380,798
                                                       ===========      ===========
</TABLE>

                                      6

<PAGE>

                    BIOTRANSPLANT INCORPORATED AND SUBSIDIARY
                          (A DEVELOPMENT STAGE COMPANY)

         NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS, CONTINUED
                                   (UNAUDITED)


3.   NET LOSS PER COMMON SHARE

Net loss per common share is based on the weighted average number of common
shares outstanding during the periods presented, in accordance with Financial
Accounting Standards Board Statement No. 128, "Earnings Per Share". Diluted net
loss per common share is the same as basic net loss per common share as the
inclusion of common stock issuable pursuant to options and warrants would be
antidilutive. Antidilutive securities not included consist of 848,369 shares
issuable pursuant to common stock options and 299,535 shares issuable pursuant
to common stock warrants.

4.   REVENUE RECOGNITION

Substantially all of the Company's license and research and development revenues
are derived from two collaborative research arrangements. Annual research and
development payments are recognized on a straight-line basis over the period of
the contract, which approximates when work is performed and costs are incurred.
License fee revenue represents technology transfer fees received for rights to
certain technology of the Company. License fees are recognized as revenue when
earned. Deferred revenue represents amounts received in advance of revenue
recognition for research and development. Research and development expenses in
the accompanying consolidated statements of operations include funded and
unfunded expenses.

Staff Accounting Bulletin No. 101 (SAB 101), "Revenue Recognition", was
issued in December 1999. SAB 101 will require companies to recognize certain
upfront non-refundable fees and milestone payments over the life of the
related alliance when such fees are received in conjunction with alliances
which have multiple elements. The Company is required to adopt this new
accounting principle through a cumulative charge to the statement of
operations, in accordance with Accounting Principles Board Opinion (APB) No.
20, "Accounting Changes", no later than October 1, 2000. The Company does not
expect adoption of this statement to have a significant impact on its
financial statements.

5.   TERM NOTE

In September 1997, the Company entered into a term note with a bank, whereby the
Company could borrow up to $500,000 for certain equipment and fixtures during a
specified drawdown period, after which time the outstanding balance will become
payable in 36 equal monthly principal installments plus interest. During 1999,
the Company amended the term note to extend the drawdown period and increase its
availability to $1.0 million under the same conditions of the original term
note. Borrowings under the term note bear annual floating interest at the bank's
Prime Rate (9.5% at September 30, 2000) during the drawdown period with an
option to convert during the repayment period to an annual fixed rate at the
three-month London Interbank Offered Rate ("LIBOR") (6.66% at September 30,
2000) plus 2.25%. Borrowings under the term note are secured by equipment and
fixtures purchased using the proceeds of the note. There were $538,636 in
borrowings outstanding under this term note at September 30, 2000.

6.   SEGMENT REPORTING

The Company has adopted Statement of Financial Accounting Standards Board (SFAS)
No. 131, "Disclosures about Segments of an Enterprise and Related Information"
("SFAS 131") which establishes standards for reporting information about
operating segments. In accordance with SFAS 131, the Company believes that it
operates in one operating segment.

7.   COMPREHENSIVE LOSS

SFAS No. 130, "Reporting Comprehensive Income" establishes standards for
reporting and display of comprehensive income or loss and its components
(revenues, expenses, gains and losses) in a full set of general-purpose
financial statements. There are no material differences between the Company's
reported loss and comprehensive loss for all periods presented.

                                      7
<PAGE>

                    BIOTRANSPLANT INCORPORATED AND SUBSIDIARY
                          (A DEVELOPMENT STAGE COMPANY)

ITEM 2. MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND
        RESULTS OF OPERATIONS

This Quarterly Report on Form 10-Q contains forward-looking statements. For
this purpose, any statements contained herein that are not statements of
historical fact may be deemed to be forward-looking statements. Without
limiting the foregoing, the words "believes," "anticipates," "plans,"
"expects," "intends," and similar expressions are intended to identify
forward-looking statements. There are a number of important factors that
could cause the Company's actual results to differ materially from those
indicated by such forward-looking statements. These factors include, without
limitation, those set forth below and elsewhere in this Quarterly Report on
Form 10-Q and in the Section titled "Business - Risk Factors That May Affect
Results" in the Company's Annual Report on Form 10-K for the year ended
December 31, 1999, as filed with the SEC, which Section is incorporated
herein by reference.

OVERVIEW

     Since commencement of operations in 1990, the Company has been engaged
primarily in the research and development of pharmaceutical products and systems
to enable the body's immune system to better tolerate the transplantation of
foreign cells, tissues and organs. The major sources of the Company's working
capital have been the proceeds from sales of equity securities, sponsored
research funding and license fees, capital lease financings, and borrowings
under a term loan. The Company has not generated any revenues from the sale of
products to date, and does not expect to receive any product revenues for
several years, if ever. The Company will be required to conduct significant
additional research, development, testing and regulatory compliance activities
that, together with general and administrative expenses, are expected to result
in significant and increasing operating losses for at least the next several
years.

     In 1993, and as amended and restated in September 1995, the Company and
Novartis entered into a collaboration agreement for the development and
commercialization of xenotransplantation products utilizing gene transduction.
Under the agreement, Novartis committed research funding and license fees
through March 1998 of $30.0 million, all of which had been received as of
December 31, 1997. Novartis has also agreed to fund certain development and
premarketing costs of products which may be developed as a result of the
collaboration, portions of which, under certain circumstances, may be repayable
from the Company's operating profits from sales of any such products.

     In October 1997, the Company and Novartis entered into a collaboration and
license agreement to develop and commercialize xenotransplantation products
utilizing the Company's proprietary mixed bone marrow chimerism technology.
Under the agreement, the Company may receive from Novartis research funding,
license fees, and milestone payments of up to $36.0 million assuming the
agreement continues for its full term and certain research objectives are met.
As of September 30, 2000, research funding of $13.5 million, license fees of
$4.0 million and milestone payments of $2.5 million had been received. In
addition to research funding, Novartis will also fund certain development and
premarketing costs of such products, portions of which may be repayable under
certain circumstances.

     In September 2000, the Company entered into an arrangement with Novartis to
combine their respective expertise in the field of xenotransplantation into a
newly formed independent company ("Newco"). Newco is expected to begin
operations in January 2001. In return for contributing its technology and $30
million in funding over three years beginning January 1, 2001, Novartis will
retain a 67% ownership share of Newco and retain the rights to commercialization
of research from Newco. In return for contributing its technology, BioTransplant
will retain a 33% share of Newco and will receive royalty payments from Novartis
sales of Newco products, if any. The formation of Newco supersedes the 1993 and
1997 Novartis agreements as amended and restated.

     In October 1995, the Company and MedImmune entered into a collaborative
research agreement for the development of products to treat and prevent organ
rejection. MedImmune paid the Company a $2.0 million license fee at the time of
execution of the agreement, and agreed to fund and assume responsibility for
clinical testing and commercialization of BTI-322 and other related products.
MedImmune has provided $2.0 million of non-refundable research support and has
agreed to make milestone payments which could total up to an additional $11.0
million. Any milestone payments which are received are repayable from royalties
on such products.

RESULTS OF OPERATIONS
THREE MONTHS ENDED SEPTEMBER 30, 2000 AND 1999

Revenues decreased to $1.8 million for the three months ended September 30, 2000
from $3.9 million for the three months ended September 30, 1999. The decrease in
revenues was primarily due to the $2.5 million milestone fee received from
Novartis in September 1999. This decrease was partially offset by an increase in
sponsored research funding from Novartis to $1.5 million during the three months
ended September 30, 2000, compared to $1.2 million in sponsored research funding
from Novartis during the three months ended September 30, 1999. Additionally,
interest income increased to $348,000 for the three months ended September 30,
2000 from $161,000 for the three months ended September 30, 1999. The increase
was due primarily to higher cash balances available for investment purposes as
well as rising interest rates.

Research and development expenses decreased to $3.6 million for the three months
ended September 30, 2000 from $3.8 million for the three months ended September
30, 1999. This decrease was primarily due to decreased levels of external
research support.

General and administrative expenses remained relatively unchanged at $664,000
for the three months ended September 30, 2000 compared to $684,000 for the three
months ended September 30, 1999.

As a result of the above factors, the Company generated a net loss for the three
months ended September 30, 2000 of $2.5 million, or $0.21 per share, compared to
a net loss of $0.6 million, or $0.07 per share for the three months ended
September 30, 1999.

                                        8
<PAGE>

                    BIOTRANSPLANT INCORPORATED AND SUBSIDIARY
                          (A DEVELOPMENT STAGE COMPANY)

NINE MONTHS ENDED SEPTEMBER 30, 2000 AND 1999

Revenues decreased to $5.5 million for the nine months ended September 30, 2000
from $6.8 million for the nine months ended September 30, 1999. The decrease in
revenues was primarily due to the $2.5 million milestone fee received from
Novartis in September 1999. This decrease was partially offset by an increase in
sponsored research funding from Novartis to $4.5 million during the nine months
ended September 30, 2000, compared to $3.7 million in sponsored research funding
from Novartis during the nine months ended September 30, 1999. Additionally,
interest income increased to $1.0 million for the nine months ended September
30, 2000 from $560,000 for the nine months ended September 30, 1999. The
increase was due primarily to higher cash balances available for investment
purposes as well as rising interest rates.

Research and development expenses decreased to $11.0 million for the nine months
ended September 30, 2000 from $11.4 million for the nine months ended September
30, 1999. This decrease was primarily due to decreased levels of external
research support.

General and administrative expenses increased to $1.9 million for the nine
months ended September 30, 2000 from $1.8 million for the nine months ended
September 30, 1999. This increase was primarily due to increases in the
Company's general corporate expenditures in the nine months ended September 30,
2000 compared to the nine months ended September 30, 1999.

As a result of the above factors the Company generated a net loss for the nine
months ended September 30, 2000 of $7.4 million, or $0.65 per share, compared to
a net loss of $6.5 million, or $0.75 per share for the nine months ended
September 30, 1999.


LIQUIDITY AND CAPITAL RESOURCES

Since its inception, the Company's operations have been funded principally
through the net proceeds of an aggregate of $80.1 million from sales of equity
securities. The Company has also received $50.9 million from research and
development and collaboration agreements with Novartis, $4.0 million from an
alliance agreement with MedImmune and $2.9 million in equipment financing. The
proceeds of the sales of equity securities, equipment financing, and cash
generated from the corporate collaborations with Novartis and MedImmune have
been used to fund operating losses of approximately $64.5 million and the
investment of approximately $5.4 million in equipment and leasehold improvements
through September 30, 2000. During 1999, the Company extended and increased its
term note with a bank from $500,000 to $1.0 million for certain equipment and
fixtures borrowing. There were $539,000 in borrowings outstanding under this
term note at September 30, 2000. The Company had no significant commitments as
of September 30, 2000 for capital expenditures.

     On February 11, 2000, the Company issued and sold to a group of investors
an aggregate of 1,215,000 shares of its common stock, $.01 par value per share,
at a purchase price of $8.00 per share, for net proceeds to the Company of
approximately $9.0 million.

     The Company has entered into sponsored research and consulting agreements
with certain hospitals, academic institutions and consultants, requiring
periodic payments by the Company. Aggregate minimum funding obligations under
these agreements, which include certain cancellation provisions, total
approximately $4.4 million, which includes approximately $4.1 million in 2000.

     The Company had cash, cash equivalents and short-term investments of $19.4
million as of September 30, 2000 as compared to $21.4 million as of December 31,
1999.

     The Company anticipates that its existing funds should be sufficient to
fund its operating and capital requirements as currently planned through 2001.
However, the Company's cash requirements may vary materially from those now
planned due to many factors, including, but not limited to, the progress of the
Company's research and development programs, the scope and results of
preclinical and clinical testing, changes in existing and potential
relationships with corporate collaborators, the time and cost in obtaining
regulatory approvals, the costs involved in obtaining and enforcing patents,
proprietary rights and any necessary licenses, the ability of the Company to
establish development and commercialization capacities or relationships, the
costs of manufacturing and other factors.

     The Company expects to incur substantial additional costs, including costs
related to research and development activities, preclinical studies, clinical
trials, obtaining regulatory approvals, manufacturing and the expansion of its
facilities. The Company will need to raise substantial additional funds, through
additional financings including public or private equity offerings and
collaborative arrangements with corporate partners. There can be no assurance
that funds will be available on terms acceptable to the Company, if at all. If
adequate funds are not available, the Company may be required to delay, scale
back or eliminate certain of its product development programs or to license to
others the right to commercialize products or technologies that the Company
would otherwise seek to develop and commercialize itself, any of which would
have a material and adverse effect on the Company.


                                        9
<PAGE>

                    BIOTRANSPLANT INCORPORATED AND SUBSIDIARY
                          (A DEVELOPMENT STAGE COMPANY)


ITEM 3. QUANTITIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISKS

The Company owns financial instruments that are sensitive to market risks as
part of its investment portfolio. The investment portfolio is used to preserve
the Company's capital until it is required to fund operations, including the
Company's research and development activities. All of these market-risk
sensitive instruments are classified as held-to-maturity and are not held for
trading purposes. The Company does not own derivative financial instruments in
its investment portfolio. The investment portfolio contains instruments that are
subject to the risk of a decline in interest rates.

INTEREST RATE RISK: The Company's investment portfolio includes investment grade
debt instruments. These bonds are subject to interest rate risk, and could
decline in value if interest rates fluctuate. Due to the short duration and
conservative nature of these instruments, the Company does not believe that it
has a material exposure to interest rate risk.


                                       10

<PAGE>

                    BIOTRANSPLANT INCORPORATED AND SUBSIDIARY
                          (A DEVELOPMENT STAGE COMPANY)

PART II. OTHER INFORMATION

Item 1.  Legal Proceedings
         Response:  None

Item 2.  Changes in Securities
         Response:  None

Item 3.  Defaults upon Senior Securities
         Response:  None

Item 4.  Submission of Matters to a Vote of Security Holders
         Response:  None

Item 5.  Other Information
         Response:  None

                                       11

<PAGE>

                    BIOTRANSPLANT INCORPORATED AND SUBSIDIARY
                          (A DEVELOPMENT STAGE COMPANY)


ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K

a)   Exhibits

     10.1 Shareholder Agreement date September 24, 2000 by and between the
          Company, Novartis AG and Loxo AG, together with exhibits

     27   Financial Data Schedule.

     99.1 Pages 14 to 24 of the Company's Annual Report on Form 10-K for the
          year ended December 31, 1999, as filed with the Securities and
          Exchange Commission, which are deemed to be filed except to the extent
          that any such portions are not expressly incorporated herein by
          reference.

b)   Reports on Form 8-K
          July 18, 2000
          August 9, 2000
          October 11, 2000


                                       12

<PAGE>

                    BIOTRANSPLANT INCORPORATED AND SUBSIDIARY
                          (A DEVELOPMENT STAGE COMPANY)


                                   SIGNATURES

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

                                  BioTransplant Incorporated
                                         (Registrant)

Date: November 13, 2000           /S/ RICHARD V. CAPASSO

                                  Richard V. Capasso
                                  Vice President, Finance and Treasurer
                                  (Principal Financial and Accounting Officer)


                                       13
<PAGE>

                                  EXHIBIT INDEX

The following exhibits are filed as part of this Quarterly Report on Form 10-Q.

<TABLE>
<CAPTION>
EXHIBIT NO.                            DESCRIPTION
-----------    -----------------------------------------------------------------
<S>            <C>
   +10.1       Shareholder Agreement date September 24, 2000 by and between the
               Company, Novartis AG and Loxo AG, together with exhibits

    27.1       Financial Data Schedule.

    99.1       Pages 14 to 24 of the Company's Annual Report on Form 10-K for
               the year ended December 31, 1999, as filed with the Securities
               and Exchange Commission, which are deemed to be filed except to
               the extent that any such portions are not expressly incorporated
               herein by reference.

</TABLE>

     +    Confidential treatment requested as to certain portions.


                                       14