<PAGE>   1


                       SECURITIES AND EXCHANGE COMMISSION
                              Washington, DC 20549

                                    Form 10-Q

                   QUARTERLY REPORT UNDER SECTION 13 OR 15 (d)
                     OF THE SECURITIES EXCHANGE ACT OF 1934


                       For Quarter Ended January 31, 2000

                          Commission File Number 1-9579


                                   Ecogen Inc.
             (Exact name of registrant as specified in its charter)



          Delaware                                             22-2487948
          --------                                             ----------
(State or other jurisdiction of                             (I.R.S. Employer
 incorporation or organization)                           Identification Number)


2000 W. Cabot Boulevard #170, Langhorne, Pennsylvania              19047
-----------------------------------------------------              -----
     (Address of principal executive offices)                    (Zip Code)



Registrant's telephone number,
including area code                      (2l5) 757-l590
                                         --------------


     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   .
                                             ---    ---

         Indicate the number of shares outstanding of each of the issuer's
classes of common stock, as of the latest practicable date:

          Class                                 Outstanding at February 29, 2000
          -----                                 --------------------------------
Common Stock, $.01 par value                              11,995,612


<PAGE>   2


                                   ECOGEN INC.


                                      INDEX


<TABLE>
<CAPTION>
                                                                                                           Page
                                                                                                           ----
<S>                                                                                                        <C>
PART I - FINANCIAL INFORMATION

  Item 1 - Financial Statements:

     Unaudited Consolidated Condensed Balance Sheets
         as of January 31, 2000 and October 31, 1999.........................................................1

     Unaudited Consolidated Condensed Statements of Operations
         for the three months ended January 31, 2000 and 1999 ...............................................2

     Unaudited Consolidated Condensed Statement of Stockholders' Equity
         for the three months ended January 31, 2000.........................................................3

     Unaudited Consolidated Condensed Statements of Cash Flows
         for the three months ended January 31, 2000 and 1999................................................4

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

  Item 2 - Management's Discussion and Analysis of Results of Operations and Financial Condition............11


PART II - OTHER INFORMATION

  Item 6(a) - Exhibits......................................................................................15
</TABLE>




<PAGE>   3
PART I - FINANCIAL INFORMATION


                          ECOGEN INC. AND SUBSIDIARIES

                 UNAUDITED CONSOLIDATED CONDENSED BALANCE SHEETS


<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------

Assets                                                               JANUARY 31, 2000                     OCTOBER 31,
                                                           PRO FORMA                 ACTUAL                   1999
                                                         (SEE NOTE 7)
----------------------------------------------------------------------------------------------------------------------
<S>                                                      <C>                     <C>                     <C>
Current assets:
   Cash                                                  $   1,392,377           $      15,377           $           0
   Trade receivables, net                                    1,767,694               1,767,694               1,685,950
   Inventory, net                                            5,909,613               5,372,613               5,358,017
   Prepaid expenses and other current assets                   460,058                 460,058                 387,043
----------------------------------------------------------------------------------------------------------------------
      Total current assets                                   9,529,742               7,615,742               7,431,010

Plant and equipment, net                                     2,231,291               2,231,291               2,374,462
Other assets, net                                            1,380,095                 815,095                 656,800
Intangible assets                                            1,816,000                      --                      --
----------------------------------------------------------------------------------------------------------------------
                                                         $  14,957,128           $  10,662,128           $  10,462,272
======================================================================================================================

Liabilities and Stockholders' Equity (Deficit)

----------------------------------------------------------------------------------------------------------------------
Current liabilities:
   Current portion of long-term debt                         2,639,375               2,639,375               2,193,145
   Accounts payable and accrued expenses                     4,125,668               4,248,668               4,010,120
----------------------------------------------------------------------------------------------------------------------
        Total current liabilities                            6,765,043               6,888,043               6,203,265

Long-term debt                                               1,148,613               1,148,613                 250,186
Long-term deferred revenue                                   1,482,569               1,482,569               1,451,928
Minority interest in subsidiary                              1,533,854               1,533,854               1,533,854
----------------------------------------------------------------------------------------------------------------------
         Total liabilities                                  10,930,079              11,053,079               9,439,233
----------------------------------------------------------------------------------------------------------------------
Stockholders' equity (Deficit):
   Preferred stock:
       Series 2000 A                                               150                      --                      --
       Series 1999 A                                                95                      95                     150
       Series 1998 C                                               324                     324                     324
   Common stock                                                118,607                 105,093                  99,859
   Additional paid-in capital                              129,182,870             124,778,534             124,554,877
   Accumulated deficit                                    (125,274,997)           (125,274,997)           (123,632,171)
----------------------------------------------------------------------------------------------------------------------
        Total stockholders' equity (deficit)                 4,027,049                (390,951)              1,023,039
----------------------------------------------------------------------------------------------------------------------
                                                         $  14,957,128           $  10,662,128           $  10,462,272
======================================================================================================================
</TABLE>



See Accompanying Notes To Unaudited Consolidated Condensed Financial Statements.


                                        1

<PAGE>   4


                          ECOGEN INC. AND SUBSIDIARIES

            UNAUDITED CONSOLIDATED CONDENSED STATEMENTS OF OPERATIONS


<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------
                                                                      THREE MONTHS ENDED
                                                                          JANUARY 31,
                                                                  2000                  1999
------------------------------------------------------------------------------------------------
<S>                                                           <C>                    <C>
Revenues:

  Product sales, net                                          $  1,099,500           $ 1,741,565
  Contract research                                                     --               515,891
------------------------------------------------------------------------------------------------
    Total revenues                                            $  1,099,500           $ 2,257,456
------------------------------------------------------------------------------------------------

Costs and expenses:

  Cost of products sold                                            906,530             1,575,159
  Research and development:
    Funded by third parties                                             --               224,676
    Self funded                                                    441,904               481,294
  Selling, general and administrative                            1,210,037             1,550,877
------------------------------------------------------------------------------------------------
    Total costs and expenses                                     2,558,471             3,832,006
------------------------------------------------------------------------------------------------
Operating loss                                                  (1,458,971)           (1,574,550)

Other income (expense):
    Interest expense, net                                         (146,247)             (111,192)
    Other income                                                    54,351                 8,306
------------------------------------------------------------------------------------------------
    Total other expense, net                                       (91,896)             (102,886)
------------------------------------------------------------------------------------------------

Net loss                                                        (1,550,867)           (1,677,436)

Dividends on preferred stock including assumed
     incremental yield of $63,219 in 2000                          155,177               102,213
------------------------------------------------------------------------------------------------

Net loss allocable to common stockholders                     $ (1,706,044)          $(1,779,649)
================================================================================================

Basic and diluted net loss per common share                   $      (0.17)          $     (0.21)
================================================================================================


Weighted average number of common shares outstanding            10,045,000             8,384,000
================================================================================================
</TABLE>


See Accompanying Notes To Unaudited Consolidated Condensed Financial Statements.


                                        2
<PAGE>   5


                          ECOGEN INC. AND SUBSIDIARIES

  UNAUDITED CONSOLIDATED CONDENSED STATEMENT OF STOCKHOLDERS' EQUITY (DEFICIT)
                      Three months ended January 31, 1999


<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------------------------------------
                                                         CONVERTIBLE                 ADDITIONAL
                                                          PREFERRED     COMMON        PAID-IN          ACCUMULATED
                                                            STOCK       STOCK         CAPITAL            DEFICIT            TOTAL
------------------------------------------------------------------------------------------------------------------------------------
<S>                                                      <C>          <C>           <C>               <C>               <C>
Balance November 1, 1999                                     $474     $ 99,859      $124,554,877      $(123,632,171)    $ 1,023,039

Dividends on preferred stock                                   --          247            26,966            (91,959)        (64,746)

Stock options granted under a consulting
    agreement in 1999                                          --           --            18,067                 --          18,067

Conversion of 5,500 shares of Series 1999 A convertible
    preferred stock to 498,747 shares of common stock         (55)       4,987            (4,932)                --              --

Issuance of 200,000 warrants in connection with
    a loan agreement                                           --           --           183,556                 --         183,556

Net loss                                                       --           --                --         (1,550,867)     (1,550,867)

------------------------------------------------------------------------------------------------------------------------------------
Balance January 31, 2000                                     $419     $105,093      $124,778,534      $(125,274,997)    $ (390,951)
====================================================================================================================================
</TABLE>



See Accompanying Notes To Unaudited Consolidated Condensed Financial Statements.


                                       3
<PAGE>   6


                          ECOGEN INC. AND SUBSIDIARIES

            UNAUDITED CONSOLIDATED CONDENSED STATEMENTS OF CASH FLOWS


<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------
                                                                             THREE MONTHS ENDED
                                                                                 JANUARY 31,
                                                                         2000                  1999
------------------------------------------------------------------------------------------------------
<S>                                                                  <C>                   <C>
Cash flows from operating activities:
   Net loss                                                          $(1,550,867)          $(1,677,436)
   Adjustments to reconcile net income (loss) to net
      cash provided by (used in) operating activities:
         Depreciation and amortization expense                           164,631               170,600
         Noncash interest and other expense                               73,968               110,943
         Changes in assets and liabilities, net                            4,448              (973,324)

------------------------------------------------------------------------------------------------------
Net cash used in by operating activities                              (1,307,820)           (2,369,217)
------------------------------------------------------------------------------------------------------

Cash flows from investing activities:
   Proceeds from maturity of temporary investments                            --               813,150
   Purchase of plant and equipment                                       (21,460)               (6,060)

------------------------------------------------------------------------------------------------------
Net cash (used in) provided by investing activities                      (21,460)              807,090
------------------------------------------------------------------------------------------------------

Cash flows from financing activities -
   Proceeds from bank loan                                             1,500,000                    --
   Repayments of line of credit, net                                     (53,770)                   --
   Repayment of capital lease obligations                               (101,573)              (23,262)

------------------------------------------------------------------------------------------------------
Net cash provided by (used in) financing activities                    1,344,657               (23,262)
------------------------------------------------------------------------------------------------------

Net increase (decrease) in cash                                           15,377            (1,585,389)

Cash and cash equivalents, beginning of period                                --             2,009,437

------------------------------------------------------------------------------------------------------
Cash and cash equivalents, end of period                             $    15,377           $   424,048
======================================================================================================
</TABLE>

                                                                     (Continued)


                                       4
<PAGE>   7


                          ECOGEN INC. AND SUBSIDIARIES

      UNAUDITED CONSOLIDATED CONDENSED STATEMENTS OF CASH FLOWS, CONTINUED

<TABLE>
<CAPTION>
------------------------------------------------------------------------------------------------------
                                                                             THREE MONTHS ENDED
                                                                                 JANUARY 31,
                                                                         2000                  1999
------------------------------------------------------------------------------------------------------
<S>                                                                  <C>                   <C>
Changes in assets and liabilities:
    Increase in receivables                                          $   (81,744)          $  (337,487)
    Increase in inventory                                                (14,596)              (11,514)
    Increase in prepaid expenses and
       other current assets                                              (73,015)              (37,507)
   Increase in other assets                                                   --               (15,202)
   Increase (decrease) in accounts payable
       and accrued expenses                                              173,803              (123,761)
   Decrease in deferred contract revenue                                      --              (447,853)

------------------------------------------------------------------------------------------------------
       Changes in assets and liabilities, net                        $     4,448           $  (973,324)
======================================================================================================


------------------------------------------------------------------------------------------------------
Noncash investing and financing activities:
------------------------------------------------------------------------------------------------------

  During the first quarter of fiscal 2000 and 1999, the Company issued 24,657 and 27,621 shares of
  common stock as dividends on the Company's preferred stock and 498,747 and 582,479 shares of its
  common stock upon conversion of the Company's convertible preferred stock.

  During the first quarter of fiscal 1999 the Company transferred 2,968 shares of treasury stock,
  to outstanding shares pursuant to certain employee benefit plans.
======================================================================================================
</TABLE>



See Accompanying Notes to Unaudited Consolidated Condensed Financial Statements.


                                       5
<PAGE>   8


                          ECOGEN INC. AND SUBSIDIARIES

         NOTES TO UNAUDITED CONSOLIDATED CONDENSED FINANCIAL STATEMENTS

                            JANUARY 31, 2000 AND 1999


(1) BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

       ORGANIZATION, LIQUIDITY AND BASIS OF PRESENTATION:

       The consolidated condensed financial statements include the accounts of
       Ecogen Inc. ("Ecogen" or the "Company") and its wholly-owned and
       majority-owned subsidiaries. All intercompany accounts and transactions
       have been eliminated in consolidation.

       The accompanying consolidated condensed financial statements include all
       adjustments (consisting of normal recurring accruals) which are, in the
       opinion of management, necessary for a fair presentation of the
       consolidated results of operations and financial position for the interim
       periods presented. The consolidated condensed financial statements have
       been prepared in accordance with the requirements for Form 10-Q and,
       therefore, do not include all disclosures of financial information
       required by generally accepted accounting principles. These consolidated
       condensed financial statements should be read in conjunction with the
       Company's October 31, 1999 consolidated financial statements and notes
       thereto included in the Company's Annual Report on Form 10-K.

       Since its inception, the Company's source of funds has been primarily
       dependent on private and public offerings of equity securities, revenues
       from research and development alliances, and product sales. In 1998, the
       Company obtained a two-year working capital line of credit; such credit
       facility expires in August 2000 and approximately $1.7 million is
       outstanding under that credit facility as of February 29, 2000. The
       Company believes that its existing working capital and amounts available
       under its working capital line of credit should be sufficient to meet its
       capital and liquidity requirements through fiscal 2000 based on reduced
       spending levels, if necessary. However, the Company's working capital
       line of credit will need to be renewed or refinanced in August 2000. (See
       note 4 of the notes to the unaudited consolidated consolidated financial
       statements.) The Company continues to evaluate various programs to raise
       additional funds, pursue strategic initiatives and refinance its working
       capital facility. At this time the Company is unable to predict whether
       it will be successful in its efforts. If the Company is not successful in
       refinancing its working capital line of credit or in raising additional
       funding, the Company would take a number of steps to conserve cash,
       including reducing expenditures.

       The results of operations for the interim period ended January 31, 2000
       are not necessarily indicative of the operating results for the full
       year.






                                                                     (Continued)




                                       6
<PAGE>   9


                          ECOGEN INC. AND SUBSIDIARIES

         NOTES TO UNAUDITED CONSOLIDATED CONDENSED FINANCIAL STATEMENTS,
                                   CONTINUED


(1) BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES,
    CONT.

       OPERATIONS:

       The Company is a biotechnology company specializing in the development
       and marketing of environmentally compatible products for the control of
       pests in agricultural and related markets. The Company has not yet
       achieved profitable operations for any of its fiscal years and there is
       no assurance that profitable operations, if achieved, could be sustained
       on a continuing basis. Further, the Company's future operations are
       dependent, among other things, on the success of the Company's
       commercialization efforts and market acceptance of the Company's
       products.

       NET LOSS PER COMMON SHARE:

       Basic loss per share is based on net loss allocable to common
       stockholders for the relevant period, divided by the weighted average
       number of common shares outstanding during the period. Diluted loss per
       share is based on net loss allocable to common stockholders for the
       relevant period divided by common shares outstanding and other potential
       common shares if they are dilutive.

       The conversion of the convertible preferred stock in fiscal 2000 and 1999
       into common shares and adding back the dividends incurred during the
       three-month periods ended January 31, 2000 and 1999, was not included in
       the net loss per share calculation since the effect was anti-dilutive.
       Stock options and warrants were not considered because they were
       anti-dilutive.

       RECLASSIFICATIONS:

       Certain reclassifications have been made to the reported amounts in the
       1999 financial statements to conform to the 2000 classifications.

(2) INVENTORY

       At January 31, 2000, inventory consisted of raw materials of $523,054,
       work-in-progress of $901,571 and finished products of $3,947,988.

(3) MONSANTO TRANSACTION

        In January 1996, the Company entered into agreements with Monsanto
        Company ("Monsanto") for an equity investment, purchase of technology
        and joint research and development arrangement relating to the Company's
        proprietary Bacillus thuringiensis ("Bt") technology for in-plant
        applications (collectively, the "Monsanto Transaction"). In January
        1998, the Company amended its research and development agreement with
        Monsanto. The amended R&D Contract ended January 1999. During the three
        months ended January 31, 1999 $.5 million was recorded as contract
        research revenue principally relating to the Monsanto R&D contract. The
        amended R&D Contract ended January 1999.

                                                                     (Continued)



                                       7
<PAGE>   10


                          ECOGEN INC. AND SUBSIDIARIES

         NOTES TO UNAUDITED CONSOLIDATED CONDENSED FINANCIAL STATEMENTS,
                                   CONTINUED

(4) LOAN AGREEMENT

        In August 1998, the Company obtained a secured, revolving working
        capital line of credit for up to $5.0 million with a financial
        institution. Up to $1.0 million of the line may be used for letters of
        credit. The working capital line of credit expires in August 2000
        (subject to earlier termination on certain events of default), bears
        interest at prime plus 3.25% and is fully collateralized by the
        Company's assets, other than certain of its intellectual property
        rights. The lending formula is based on eligible receivables and
        finished goods inventory. At February 29, 2000, the balance outstanding
        under the line was $1.7 million. The loan agreement contains certain
        financial covenants and has certain restrictions on the Company's
        ability to pay dividends on its common stock. At January 31, 2000 the
        Company was not in compliance with such covenants; however such non
        compliance has been waived by the lender.

        On December 24, 1999, the Company obtained a secured loan for $1.5
        million with a financial institution that is controlled by a principal
        stockholder of the Company. The loan requires a $0.5 million principal
        payment in June 2000 with the balance due in June 2001. The loan bears
        interest at prime plus 2% and is payable monthly. The loan is
        collateralized by the Company's assets. The loan is guaranteed by a
        corporation controlled by one of the Company's principal shareholders.
        In connection with the guarantee, the corporation was issued a five-year
        warrant to purchase 200,000 shares of the Company's common stock at
        $1.25 per share. Such warrants have a value of $183,556 which has been
        recorded as deferred debt expense. Such amount is being amortized as
        interest expense over the life of the loan.

(5) STOCKHOLDERS' EQUITY

       During the first quarter of fiscal 2000, the Company issued 498,747
       shares of its common stock in exchange for 5,500 shares of the Company's
       Series 1999-A 7% convertible preferred stock issued in May 1999. The
       Company also issued 24,657 shares of its common stock in payment of
       cumulative dividends at the time of conversion.

(6) SUBSEQUENT EVENTS

       PREFERRED STOCK:

       Series 2000-A Convertible Preferred Stock:
       On February 14, 2000, the Company sold 15,000 shares of Series 2000-A 7%
       convertible preferred stock, stated value $100 per share, to
       institutional investors for net proceeds of $1.4 million. The holders of
       the preferred stock were issued five-year warrants to purchase up to
       200,000 shares of common stock at $2.66 per share. Dividends are payable
       quarterly in cash or stock at the option of the Company. The preferred
       stock has no voting rights except with respect to certain matters
       affecting the Company's preferred stock. At the election of


                                                                     (Continued)


                                       8
<PAGE>   11


                          ECOGEN INC. AND SUBSIDIARIES

         NOTES TO UNAUDITED CONSOLIDATED CONDENSED FINANCIAL STATEMENTS,
                                   CONTINUED


(6) SUBSEQUENT EVENTS, CONT.

       PREFERRED STOCK, CONT.:

       Series 2000-A Convertible Preferred Stock, cont.:
       the holders, the preferred stock may be converted at various dates to
       shares of the Company's common stock at the lesser of $2.73 per share or
       95% of the average market price, as defined in the agreement, over a
       twenty-day period at the time of conversion. The Company, at its option,
       may redeem the preferred stock at 125% of the stated value. If the
       Company is unable to issue sufficient shares of common stock within a
       specified period of time after the holder has requested conversion, the
       dividend rate may increase and the Company may be required to issue
       additional warrants. Further, in certain circumstances, all of which are
       in the control of the Company, the Company may be required to redeem the
       shares at various premiums over stated value. The holders of the
       preferred stock have certain registration rights with respect to the
       shares of common stock underlying the warrants and the convertible
       preferred stock. Included in the fee paid to the placement agent in
       connection with the transaction were 20,000 shares of the Company's
       common stock. In accordance with the terms of the Series 2000-A preferred
       stock the Company is required to recognize an assumed incremental yield
       of $592,496 (calculated at the date of issuance based on the conversion
       formula in the agreement). Such amounts will be amortized as preferred
       stock dividends over a seven-month period beginning with the date of
       issuance.

       ACQUISITION:

       On February 15, 2000, the Company completed its acquisition of certain
       assets of the sprayable Bt bioinsecticide business of Mycogen
       Corporation, an affiliate of Dow AgroSciences LLP. The Company issued
       1,351,351 shares of the Company's common stock valued at $3,000,000 upon
       the closing of the transaction. Prior to the closing, the Company
       acquired approximately $391,000 of Mycogen's inventory of sprayable Bt
       products, under a distribution agreement effective January 1, 2000. Under
       the terms of the agreement, Mycogen has agreed to hold the shares for a
       three-year period, except in the event of certain change in control
       transactions. Mycogen was granted certain demand and piggyback
       registration rights with respect to the shares. In addition, Mycogen has
       the right of first refusal to purchase securities of the Company so as to
       maintain its ownership percentage in the Company. Mycogen also has been
       granted certain market price protection rights at the time that Mycogen
       sells the shares which may result in the issuance of additional shares,
       which may not exceed 20% of the Company's outstanding shares without
       stockholder approval. The Company and Dow AgroSciences LLC also entered
       into a five- year supply agreement and the companies have agreed to enter
       into distribution agreements granting exclusive rights to Dow
       AgroSciences to sell the acquired products in Mexico, New Zealand and
       Australia.




                                       9
<PAGE>   12


                          ECOGEN INC. AND SUBSIDIARIES

         NOTES TO UNAUDITED CONSOLIDATED CONDENSED FINANCIAL STATEMENTS,
                                   CONTINUED


       ACQUISITION, CONT.:

       The transaction will be accounted for as a purchase and, accordingly, the
       total purchase price for the assets of $3,425,000, including out of
       pocket expenses, will be allocated based upon their fair value at the
       date of acquisition. The assets acquired include inventory and certain
       identifiable intangible assets including a license to certain genes and
       strains and product registration and data citation rights. Included in
       the purchase price is inventory acquired and sold by the Company under a
       distribution agreement. The agreement also provides that the Company has
       no obligation for past or future royalties under a 1998 settlement
       agreement with Mycogen on a patent infringement dispute. Under purchase
       accounting, part of the purchase price has been allocated to other assets
       for the fully paid up royalty and any amounts previously accrued under
       the settlement agreement have been eliminated in purchase accounting.

       The unaudited pro forma balance sheet at January 31, 2000 has been
       adjusted as follows for the allocation of the purchase price from the
       Mycogen acquisition:

<TABLE>
<CAPTION>
                                                                 Debit (Credit)
                                                                 --------------
         <S>                                                     <C>
         Inventory                                                     537,000
         Other assets                                                  565,000
         Accrued liabilities                                           123,000
         Intangible assets                                           1,816,000
         Common stock and additional paid in capital                (3,041,000)
</TABLE>

       The allocation of the purchase price is subject to adjustment based on
       the final determination of fair value at the date of acquisition.

(7) UNAUDITED PRO FORMA CONSOLIDATED BALANCE SHEET

       The unaudited pro forma consolidated balance sheet presented is based
       upon the Company's historical consolidated balance sheet at January 31,
       2000 after giving effect to (i) the $1,377,000 net proceeds from the sale
       of the Series 2000-A convertible preferred stock, and (ii) the
       acquisition of Mycogen Corporation's sprayable Bt product line as
       described in note 6 of the notes to unaudited consolidated condensed
       financial statements.




                                       10
<PAGE>   13


                          ECOGEN INC. AND SUBSIDIARIES

                     MANAGEMENT'S DISCUSSION AND ANALYSIS OF
                  RESULTS OF OPERATIONS AND FINANCIAL CONDITION

                  THREE MONTHS ENDED JANUARY 31, 2000 AND 1999


OVERVIEW

Total revenues decreased $1.2 million or 51% in fiscal 2000 to $1.1 million from
$2.3 million in fiscal 1999. Net product sales decreased 37% from $1.7 million
in fiscal 1999 to $1.1 million in fiscal 2000. The Company had a $.9 million
backlog at January 31, 2000 for orders received but not shipped including $.4
million of recently acquired Mycogen products. Contract research revenue
decreased $.5 million due primarily to the expiration in January 1999 of the
research and development contract with Monsanto.

During the first quarter of fiscal 2000, the Company realized a reduction in
operating expenses of 27% from $2.3 million in the year-ago period to $1.7
million in the first quarter of fiscal 2000. For the first quarter of fiscal
2000, the Company reported a net loss allocable to common stockholders of $(1.7)
million or $(.17) per basic and diluted common share compared to a net loss
allocable to common stockholders of $(1.8) million or $(.21) per basic and
diluted common share on weighted average shares of 10.0 million and 8.4 million
in the first quarter of fiscal 2000 and 1999, respectively.

THREE MONTHS ENDED JANUARY 31, 2000 AND 1999

REVENUES

Net product sales decreased $.6 million or 37% principally due to volume. The
Company had a $.9 million backlog at January 31, 2000 for orders received but
not shipped, including $.4 million of recently acquired Mycogen products. Sales
of the Company's Bt product line, representing 92% of Company product sales,
decreased 39% in fiscal 2000. The decrease was principally due to $.8 million of
product sales in fiscal 1999 sold to FMC Corporation upon the signing of an
agreement to distribute Lepinox in the United States. No comparable sale to FMC
occurred in the first quarter of fiscal 2000. Fiscal 2000 product sales to FMC
are expected to occur closer to the growing season. The decrease in Lepinox
sales was partially offset by $.5 million in product sales of two of the
recently acquired Mycogen products Mattch(TM) for caterpillar control in
vegetables, vines, and tree fruit and MVP(R)II for caterpillar control in tree
nuts and tree fruit. Biofungicide product sales, which represented 2% of product
sales in fiscal 2000, decreased $.1 million from the year-ago period,
principally due to lower sales of AQ10, the Company's biofungicide for control
of powdery mildew. Other product sales increased from nothing in the first
quarter of fiscal 1999 to 6% of product sales in fiscal 2000 principally
representing soil amendments.

Contract research revenues decreased $.5 million in fiscal 2000 due to the
expiration in January 1999 of the research and development agreement with
Monsanto that had contributed more than $10 million in contract research revenue
over its three-year term.



                                       11
<PAGE>   14


COSTS AND EXPENSES

Cost of products sold decreased 42% in the first three months of fiscal 2000
compared to the same period in fiscal 1999 due primarily to a 37% decrease
in product sales. Gross margins improved from 10% in fiscal 1999 to 18% in
fiscal 2000. The higher gross margins in fiscal 2000 were due principally to
lower margin international Bt sales being replaced by higher margin domestic Bt
sales, including sales of the Mycogen products.

Total operating expenses were $1.7 million in the first quarter of fiscal 2000,
compared to $2.3 million in fiscal 1999, a decrease of 27%. Research and
development costs decreased $.3 million or 37% due principally to lower
personnel costs. The Company's commitment to provide research services to
Monsanto expired in January 1999 and the Company's technology continues to
approach commercialization, therefore requiring less activity in basic research
and process development. Selling, general and administrative expenses were $1.2
million in the first quarter of fiscal 2000 compared to $1.6 million in 1999
representing a decrease of $.3 million or 22% due to lower selling and marketing
expenses resulting from lower product sales and to lower general and
administrative personnel costs.

The operating loss improved from $(1.6) million in fiscal 1999 to $(1.5) million
in fiscal 2000. The improvement was due to improved gross margins and decreased
operating expenses.

NET LOSS

Net loss allocable to common stockholders for the three months ended January 31,
2000 was $(1.7) million, compared to a net loss allocable to common stockholders
of $(1.8) million for the same period in fiscal 1999. Basic and diluted net loss
per share for the three months ended January 31, 2000 was $(.17), compared to
net loss per share of $(.21) in the first quarter of fiscal 1999 on weighted
average shares outstanding of 10.0 million and 8.4 million in the first three
months of fiscal 2000 and 1999, respectively. Net loss allocable to common
stockholders included preferred stock dividends of $91,958 and $102,213 in
fiscal 2000 and 1999, respectively and an assumed incremental yield of $63,219
in fiscal 2000.

SEASONALITY OF BUSINESS

The bulk of the Company's current products are presently marketed for
agricultural applications in the northern hemisphere, where the growing season
generally runs from spring through fall. Because of the seasonal nature of its
business, the Company's product revenues are likely to be concentrated in the
fiscal quarters prior to and during a particular growing season which may result
in substantial variations in quarter-to-quarter financial results. Product sales
from year-to-year are also affected by unusual weather conditions, such as
droughts or floods, and the level of insect pressure in grower areas. In
addition, commercial introduction of the Company's new products is contingent
on, among other factors, completion of field testing and receipt of required
regulatory approvals. Unusual weather conditions during field tests or failure
to receive regulatory approvals prior to the growing season may require
additional field tests in subsequent growing seasons, with resulting delays in
product development and commercialization.

LIQUIDITY AND CAPITAL RESOURCES

During the first quarter of fiscal 2000, the Company used $1.3 million of cash
for operations. In December 1999, the Company obtained a $1.5 million variable
rate secured loan. Principal on this loan is required to be repaid in 2000 and
2001. The



                                       12
<PAGE>   15


proceeds of the loan were used to fund operations and make payments on the
Company's working capital line of credit and capital leases.

In February 2000, the Company raised net proceeds of $1.4 million pursuant to a
private placement of 7% convertible preferred stock transaction to institutional
investors. In accordance with the terms of the preferred stock, the Company is
required to recognize a non-cash, assumed incremental yield of approximately $.6
million, calculated at the date of issuance based on 95% of the average
conversion feature, as defined in the agreement. The terms of the preferred
stock transaction are disclosed in note 6 of the notes to the consolidated
financial statements.

On February 15, 2000, the Company completed its acquisition of certain sprayable
Bt biopesticides from Mycogen Corporation, an affiliate of Dow AgroSciences Inc.
(the "Mycogen Transaction") for aggregate consideration of $3.4 million
including shares of common stock with a market value of $3.0 million. (See note
6 of notes to the unaudited consolidated condensed financial statements.)

To date, the Company has not generated positive cash flow from operations. The
Company believes that its existing working capital and amounts available under
its working capital line of credit should be sufficient to meet its capital and
liquidity requirements through fiscal year 2000 based on reduced spending
levels, if necessary. However, the Company's two-year working capital line of
credit for up to $5.0 million expires in August 2000. At February 29, 2000 $1.7
million is outstanding under this credit facility. Further, the Company's
working capital and working capital requirements are affected by numerous
factors and there is no assurance that such factors will not have a negative
impact on the Company's liquidity. Principal among these factors are the success
of its product commercialization and marketing efforts and the efforts of its
strategic partners in commercializing and selling products based on the
Company's technology, the technological advantages and pricing of the Company's
products, economic and environmental considerations which impact agricultural
crop production and the agricultural sector generally, competitive conditions in
the agricultural pest control market, and access to capital markets that can
provide the Company with the resources when necessary to fund its strategic
priorities.

The Company continues to pursue the raising of additional funds and other
strategic initiatives to improve its working capital position and its capital
structure. Also, during fiscal 2000 the Company will need to extend its working
capital line of credit with its current lender or obtain alternative financing.
There is no assurance that access to financings will be available on terms
acceptable to the Company or at all. If the Company is not successful in
refinancing its working capital line of credit or in raising additional funding,
the Company would take a number of steps to conserve cash, including reducing
expenditures to provide the necessary resources to repay the outstanding
balances under its line of credit. Over the long-term, the Company's liquidity
is dependent on market acceptance of its products and technology.

RECENTLY ISSUED ACCOUNTING STANDARDS

In June 1998, the Financial Accounting Standards Board (FASB) issued Statement
of Financial Accounting Standards (SFAS) No. 133, Accounting for Derivative
Instruments and Hedging Activities which becomes effective for our financial
statements beginning November 1, 2001. SFAS No. 133 requires a company to
recognize all derivative instruments as assets or liabilities in its balance
sheet and measure them at fair value. We do not expect adoption of this standard
to have a material impact on our financial statements.


                                       13
<PAGE>   16


In December 1999, the staff of the Securities and Exchange Commission issued
Staff Accounting Bulletin No. 101, Revenue Recognition in Financial Statements
(SAB 101). SAB 101 summarizes certain of the staff's views in applying generally
accepted accounting principles to revenue recognition in financial statements.
SAB 101 requires a company to follow its guidance no later than the first
quarter of its fiscal year beginning after December 15, 1999 through a
cumulative effect of a change in accounting principle. We do not expect adoption
of this standard to have a material impact on our financial statements.

FORWARD-LOOKING STATEMENTS

The discussion set forth by the Company in this report contains forward-looking
statements. Forward-looking statements include statements concerning plans,
objectives, goals, strategies, future events or performance and underlying
assumptions and other statements which are other than historical facts. Although
the Company believes that its expectations are based on reasonable assumptions,
the Company operates in a high technology, emerging market environment that
involves a number of risks and uncertainties that could cause actual results to
differ materially from expected results. The Company intends to market and sell
a number of new and recently introduced products. Some of these products utilize
new formulations which have not to date been produced on a commercial scale or
produced on a commercial scale that has been replicated. Certain of the
manufacturing processes for such products include newly developed equipment and
techniques which are being incorporated into commercial scale manufacturing
processes. Risks and uncertainties associated with the successful
commercialization of the products include: (i) the successful scale-up of the
Company's manufacturing process in time to meet targeted sales opportunities;
(ii) the market acceptance of the Company's current and newly introduced
products; (iii) the efficacy, pricing, ease of use and performance of the
Company's products; (iv) the successful development, registration,
commercialization and marketing of technologically advanced new products; (v)
the continued and uninterrupted supply of the Company's products from
third-party toll manufacturers and the continued financial viability of such
manufacturers; (vi) economic and environmental considerations which impact
agricultural crop production and agricultural crop protection, including the
number of acres of target crops planted, the cost and efficacy of competitive
products, weather conditions and the level of insect and disease infestation on
target crops, and (vii) the ability of the Company to fund its strategic
priorities through operations or access to capital which may be dependant on
maintaining its NASDAQ listing. See additional discussion under "factors that
may affect future results" in the Company's annual report on form 10-K for the
fiscal year ended October 31, 1999, and other factors detailed from time to time
in the Company's other filings with the Securities and Exchange Commission. The
Company does not undertake to update the results discussed herein as a result of
changes in risks or operating results.




                                       14
<PAGE>   17


PART II - OTHER INFORMATION

Item 6            Exhibits and reports in Form 8-K

<TABLE>
<CAPTION>
(a) Exhibits

Exhibit No.                Description
-----------                -----------
<S>                        <C>
   3.1                     Restated Certificate of Incorporation of Ecogen Inc.
                           (Form 10-Q for fiscal quarter ended January 31,
                           1996)*

   3.2                     By-laws of Ecogen Inc., as amended (Form S-1
                           Registration Statement, File No. 33-14119)*

   3.3                     Certificate of Designations, Preferences and Rights
                           of Series 1998-A Convertible Preferred Stock (Form
                           10-Q for fiscal quarter ended April 30, 1998)*

   3.4                     Certificate of Designations, Preferences and Rights
                           of Series 1998-C Convertible Preferred Stock (Form
                           8-K, dated September 2, 1998)*

   3.5                     Certificate of Designations, Preferences and Rights
                           of Series 1999-A Convertible Preferred Stock (Form
                           10-Q, for fiscal quarter ended April 30, 1999)*

   3.6                     Certificate of Designations, Preferences and Rights
                           of Series 2000-A Convertible Preferred Stock (Form
                           10-K, for fiscal year ended October 31, 1999)*

10.153                     Asset Purchase and License Agreement between Ecogen
                           Inc. and Mycogen Corporation dated as of February 15,
                           2000 (Current Report on Form 8-K dated March 1,
                           2000)*

10.154                     Stockholders Agreement between Ecogen Inc. and
                           Mycogen Corporation dated February 15, 2000 (Current
                           Report on Form 8-K dated March 1, 2000)*

10.155                     Purchase and Sale Agreement between Ecogen Inc. and
                           Dow AgroSciences LLC dated as of February 15, 2000
                           (Current Report on Form 8-K dated March 1, 2000)*

10.156                     Convertible Preferred Stock Purchase Agreement
                           between Ecogen Inc. and Amro International, S.A.,
                           Aspen International, Ltd. and Markham Holdings
                           Limited dated as of February 14, 2000

10.157                     Registration Rights Agreement between Ecogen Inc. and
                           Amro International, S.A., Aspen International, Ltd.
                           and Markham Holdings Limited dated as of February 14,
                           2000
</TABLE>



                                       15
<PAGE>   18


<TABLE>
<S>                        <C>
10.158                     Warrant Agreement between Ecogen Inc. and Amro
                           International, S.A. dated February 14, 2000

10.159                     Warrant Agreement between Ecogen Inc. and Aspen
                           International, Ltd. dated February 14, 2000

10.160                     Warrant Agreement between Ecogen Inc. and Markham
                           Holdings Limited dated as of February 14, 2000


(b) Current Reports on Form 8-K

                  The Company filed a Current Report on Form 8-K on March 1,
2000 describing the purchase of assets from Mycogen Corporation.


27                         Financial Data Schedule
</TABLE>



*  These items are hereby incorporated by reference from the exhibits of the
   filing or report indicated and are made part of this Report.







                                       16
<PAGE>   19


                                   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.


Date:  March 16, 2000


                                     ECOGEN INC.



                                     By: /s/ James P. Reilly, Jr
                                         ---------------------------------------
                                         James P. Reilly, Jr.
                                         Chairman and Chief Executive Officer



                                     By: /s/ Michael Johnson
                                         ---------------------------------------
                                         Michael Johnson
                                         Vice President and Corporate Controller






                                       17