<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, 1998

                          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)



   2005 Cabot Boulevard West, 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 (l) has filed all reports
required to be filed by Section l3 or l5 (d) of the Securities Exchange Act of
l934 during the preceding l2 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:

<TABLE>
<CAPTION>
         Class                         Outstanding at March 1, l998
<S>                                    <C>
Common Stock, $.01 par value                     8,005,309
</TABLE>


<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, l998 and October 3l, l997.......................................  1

     Unaudited  Consolidated Condensed Statements of Operations 
         for the three months ended January 31, 1998 and 1997........................  2

     Unaudited Consolidated Condensed Statement of Stockholders'
         Equity for the three months ended January 31, l998..........................  3

     Unaudited Consolidated Condensed Statements of Cash Flows
         for the three months ended January 31, l998 and l997........................  4

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

     Item 2 - Management's Discussion and Analysis of Results
         of Operations and Financial Condition.......................................  9


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,                OCTOBER 31,
                                                                                            1998                       1997
-------------------------------------------------------------------------------------------------------------------------------
<S>                                                                                     <C>                       <C>
Current  assets:                                                                                           
   Cash, cash  equivalents and temporary investments ...............................    $   4,831,886             $   2,373,945
   Trade receivables ...............................................................        1,368,421                 1,769,514
   Inventory, net ..................................................................        8,671,843                 8,356,767
   Prepaid expenses and other current assets .......................................          662,700                   571,227
-------------------------------------------------------------------------------------------------------------------------------
      Total  current  assets                                                               15,534,850                13,071,453
-------------------------------------------------------------------------------------------------------------------------------
                                                                                                           
Plant and equipment, net ...........................................................        3,451,962                 3,649,579
Intangible and other assets, net ...................................................          835,662                   837,020
-------------------------------------------------------------------------------------------------------------------------------
                                                                                        $  19,822,474             $  17,558,052
===============================================================================================================================

LIABILITIES AND STOCKHOLDERS' EQUITY                                                  
                                                                                      
-------------------------------------------------------------------------------------------------------------------------------
                                                                                      
Current liabilities:                                                                  
   Accounts  payable  and  accrued  expenses .......................................    $   5,577,845             $   5,043,626
   Deferred  contract  revenue .....................................................        2,044,333                   957,794
-------------------------------------------------------------------------------------------------------------------------------
        Total  current  liabilities                                                         7,622,178                 6,001,420
-------------------------------------------------------------------------------------------------------------------------------
                                                                                      
Long-term debt .....................................................................        3,866,116                 3,916,432
Other long-term obligations ........................................................        2,705,659                 2,770,548
Stockholders'  equity:                                                                
   Common  stock,  par  value  $.01  per  share;  authorized  42,000,000  shares;     
         issued 8,118,573 shares  in  1998 and 1997 ................................           81,186                    81,186
   Additional  paid-in  capital ....................................................      117,823,144               117,861,372
   Accumulated  deficit ............................................................     (110,798,171)             (111,552,038)
   Other ...........................................................................       (1,477,638)               (1,520,869)
-------------------------------------------------------------------------------------------------------------------------------
        Total  stockholders'  equity                                                        5,628,521                 4,869,651
-------------------------------------------------------------------------------------------------------------------------------
                                                                                        $  19,822,474             $  17,558,052
===============================================================================================================================
</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,
                                                                 1998              1997
-------------------------------------------------------------------------------------------
<S>                                                           <C>               <C>
Revenues:

  Product  sales,  net ....................................   $ 1,715,937       $   912,102
  Contract research .......................................       719,844           710,301
  License and other income ................................     2,500,000              --
  Interest income, net ....................................          --              61,450
-------------------------------------------------------------------------------------------
     Total revenues                                             4,935,781         1,683,853
-------------------------------------------------------------------------------------------

Costs and expenses:

  Cost of products sold ...................................     1,406,584           685,510
  Research and development:
    Funded by third parties ...............................       224,920           240,807
    Self funded ...........................................       737,848         1,194,444
  Selling, general and administrative .....................     1,680,821         1,787,689
  Interest expense, net ...................................       131,741              --
-------------------------------------------------------------------------------------------
     Total  costs and expenses                                  4,181,914         3,908,450
-------------------------------------------------------------------------------------------

-------------------------------------------------------------------------------------------
Net income (loss)                                             $   753,867       ($2,224,597)
===========================================================================================
Basic and diluted net income (loss)  per  common  share
  available to common stockholders                            $      0.09       ($     0.28)
===========================================================================================
Weighted average number of common shares outstanding            8,032,000         7,844,000
===========================================================================================
</TABLE>


See Accompanying Notes to Unaudited Consolidated Condensed Financial Statements.

                                       2

<PAGE>   5

                          ECOGEN INC. AND SUBSIDIARIES

       UNAUDITED CONSOLIDATED CONDENSED STATEMENT OF STOCKHOLDERS' EQUITY
                      Three months ended January 31, 1998

<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------------------------
                                                                        ADDITIONAL                         OTHER
                                                             COMMON      PAID-IN        ACCUMULATED     STOCKHOLDERS'
                                                             STOCK       CAPITAL          DEFICIT          EQUITY         TOTAL
----------------------------------------------------------------------------------------------------------------------------------
<S>                                                        <C>        <C>              <C>              <C>             <C>    
Balance November 1, 1997                                   $ 81,186   $ 117,861,372    ($111,552,038)   ($1,520,869)    $4,869,651

Transfer of 3,629 shares of treasury stock for employee
   benefits ............................................       --           (38,228)            --           47,395          9,167

Net reduction in unrealized gain on securities .........       --              --               --           (4,164)        (4,164)

Net  income ............................................       --              --            753,867           --          753,867

----------------------------------------------------------------------------------------------------------------------------------
Balance January 31, 1998                                   $ 81,186   $ 117,823,144    ($110,798,171)   ($1,477,638)    $5,628,521
==================================================================================================================================
</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,
                                                                              1998             1997
------------------------------------------------------------------------------------------------------
<S>                                                                       <C>              <C>
Cash flows from operating activities:                                    
   Net  income (loss) ................................................    $   753,867      ($2,224,597)
   Adjustments  to  reconcile  net  income (loss)  to  net               
      cash provided  by ( used  in ) operating  activities:              
         Depreciation  and  amortization  expense ....................        201,373           93,664
         Unrealized foreign currency transaction loss ................           --             (1,627)
    Changes  in  assets  and  liabilities, net .......................      1,631,773       (1,816,124)
                                                                         
------------------------------------------------------------------------------------------------------
Net  cash provided by (used in) operating  activities                       2,587,013       (3,948,684)
------------------------------------------------------------------------------------------------------
                                                                         
Cash flows from investing activities:                                    
   Proceeds from maturities of  temporary  investments ...............           --          1,490,342
   Purchase  of  plant and  equipment ................................        (58,756)        (223,804)
                                                                         
------------------------------------------------------------------------------------------------------
Net  cash (used in) provided by investing  activities                         (58,756)       1,266,538
------------------------------------------------------------------------------------------------------
                                                                         
Cash flows from financing activities:                                    
   Repayment of capital lease obligation .............................        (70,316)         (94,360)
                                                                         
------------------------------------------------------------------------------------------------------
Net  cash used in  financing  activities                                      (70,316)         (94,360)
------------------------------------------------------------------------------------------------------
                                                                         
------------------------------------------------------------------------------------------------------
Effect  of  foreign  exchange  rate  changes  on  cash                           --             (2,004)
------------------------------------------------------------------------------------------------------
                                                                         
Net increase  (decrease)  in  cash  and  cash  equivalents ...........      2,457,941       (2,778,510)
                                                                         
Cash  and  cash  equivalents,  beginning  of  period .................      2,373,945        5,620,701
                                                                         
------------------------------------------------------------------------------------------------------
Cash  and  cash  equivalents,  end  of  period                            $ 4,831,886      $ 2,842,191
======================================================================================================
</TABLE>

                                                                     (Continued)

                                       4

<PAGE>   7

                          ECOGEN INC. AND SUBSIDIARIES

      UNAUDITED CONSOLIDATED CONDENSED STATEMENTS OF CASH FLOWS, CONTINUED

<TABLE>
<CAPTION>
-----------------------------------------------------------------------------------------
                                                                   THREE MONTHS ENDED
                                                                       JANUARY 31,
                                                                 1998             1997
-----------------------------------------------------------------------------------------
<S>                                                          <C>              <C>
Changes  in  assets  and  liabilities:
    Decrease in  receivables .............................   $   401,093      $   259,778
    Increase  in  inventory ..............................      (315,076)        (374,131)
    (Increase) decrease in  prepaid  expenses  and
       other  current  assets ............................       (91,473)          18,352
    Decrease in other assets .............................          --             66,920
    Increase (decrease) in  accounts  payable
       and  accrued  expenses ............................       615,579       (1,360,143)
    Increase (decrease)  in  deferred  contract  revenue .     1,086,539         (388,489)
    Decrease in other long-term liabilities ..............       (64,889)         (38,411)

-----------------------------------------------------------------------------------------
       Changes  in  assets  and  liabilities,  net           $ 1,631,773      ($1,816,124)
=========================================================================================
</TABLE>

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

  During the first quarter of fiscal 1997, the Company issued 1,700 shares of
  common stock as dividends on the Company's preferred stock and 44,030 shares
  of its common stock upon conversion of the Company's convertible preferred
  stock.

  During the first quarter of fiscal 1998 and 1997, the Company transferred
  3,629 and 1,415 shares of treasury stock, respectively, to outstanding shares
  pursuant to certain employee benefit plans.
================================================================================


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, 1998 AND 1997



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

       ORGANIZATION 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 l0-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, l997 consolidated financial statements and notes
       thereto included in the Company's Annual Report on Form 10-K.

       The results of operations for the interim period ended January 31, 1998
       are not necessarily indicative of the operating results for the full
       year.

       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.


                                                                     (Continued)
                                       6

<PAGE>   9

                          ECOGEN INC. AND SUBSIDIARIES

    NOTES TO UNAUDITED CONSOLIDATED CONDENSED FINANCIAL STATEMENTS, CONTINUED


       NET INCOME (LOSS) PER COMMON SHARE:

       In February 1997, the Financial Accounting Standards Board issued
       Statement of Financial Accounting Standard No. 128, "Earnings Per Share"
       ("SFAS No. 128"). The Company adopted SFAS No. 128 in the first quarter
       of fiscal 1998.

       Under SFAS No. 128, basic income (loss) per share is based on net income
       (loss) for the relevant period, divided by the weighted average number of
       common shares outstanding during the period. Diluted income (loss) per
       share is based on net income (loss) for the relevant period divided by
       common shares outstanding and other potential common shares if they are
       dilutive.

       There is no difference between the Company's historic net loss per share
       calculation and basic and diluted net loss as calculated under SFAS No.
       128 because all other potential common shares were anti-dilutive since
       the Company reported a net loss. For the current period, diluted earnings
       per share were calculated giving effect to the conversion of the
       $3,000,000 convertible note into 1,000,000 common shares in accordance
       with the terms of the note, and adding back the $61,000 of interest
       expense incurred during the period on the note. Stock options and
       warrants were not considered because they were anti-dilutive.

(2)    INVENTORY

       At January 31, l998, inventory consisted of raw materials of $2,042,326,
       work-in-progress of $1,449,129 and finished products of $5,180,388.

(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
       and received approximately $4.3 million in cash payments which resulted
       in $2.5 million in other revenues earned and recorded in the first
       quarter of fiscal 1998 for which the Company has no continuing
       obligation. At January 31, 1998 the balance of deferred contract revenue
       from Monsanto is approximately $2.0 million which will be recognized as
       income when earned through January 1999, the remaining term of the
       amended agreement.


                                       7

<PAGE>   10
                                                                     (Continued)

                          ECOGEN INC. AND SUBSIDIARIES

   NOTES TO UNAUDITED CONSOLIDATED CONDENSED FINANCIAL STATEMENTS, (CONTINUED)


(4)    COMMITMENTS AND CONTINGENCIES

       Subsequent to January 31, 1998 the Company entered into a $700,000 letter
       of credit to secure a contract manufacturing agreement. A $500,000
       certificate of deposit is being maintained as collateral for the letter
       of credit.


                                       8

<PAGE>   11

                          ECOGEN INC. AND SUBSIDIARIES

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

                  THREE MONTHS ENDED JANUARY 31, 1998 AND 1997


OVERVIEW

For the first three months of fiscal 1998, total revenues almost tripled from
$1.7 million in 1997 to $4.9 million in 1998. During the first quarter of fiscal
1998, the Company amended its research and development agreement with Monsanto
Company (Monsanto) which resulted in $2.5 million of non-recurring revenues in
the first quarter of fiscal 1998. Product sales increased 88% from $.9 million
to $1.7 million for the three months ended January 31, 1997 and 1998,
respectively. During the first quarter of fiscal 1998, the Company also realized
a reduction in operating expenses of 18% from $3.2 million in the year-ago
period to $2.6 million. As a result of increased revenues and decreased
operating expenses, the Company reported net income of $.8 million or $.09 per
basic and diluted share in the first quarter of fiscal 1998 compared to a net
loss of ($2.2) million or ($.28) per share in 1997 on weighted average shares of
8.0 million and 7.8 million in the first quarter of fiscal 1998 and 1997,
respectively. Exclusive of non-recurring revenues from Monsanto, the Company's
net loss for the first quarter of fiscal 1998 improved 19% to ($1.7) million,
from a net loss of ($2.2) million for the first quarter of fiscal 1997. Basic
and diluted net loss per common share, exclusive of non-recurring revenues, was
($.22), compared with a net loss per common share of ($.28) for the first
quarter of fiscal 1997.

THREE MONTHS ENDED JANUARY 31, 1998 AND 1997

REVENUES

Net product sales increased 88% during the three months ended January 31, 1998
to $1.7 million compared with $.9 million in the first quarter of 1997. Sales of
the Company's Bt product line, representing 39% of total sales, increased 34%
due principally to increased volume as a result of first time, first quarter
sales of CRYMAX, the Company's new Bt bioinsecticide for control of caterpillars
in the vegetable, tree nut and vine market. The increase in CRYMAX sales was
partially offset by a decrease in volume of other Bt products. Pheromone product
sales, representing 60% of total sales, increased $.9 million or 503%
principally due to sales of the Company's new NoMate OLR product for control of
omnivorous leafrollers in grapes and kiwi. Biofungicide sales, representing 1%
of total sales, decreased $.2 million.


                                       9

<PAGE>   12

REVENUES (CONTINUED)

Other revenues increased $2.4 million in the current period, due primarily to
the non-recurring up-front payment from Monsanto described above as a result of
an amendment to the Company's research and development contract with Monsanto.

COSTS AND EXPENSES

Cost of products sold increased 105% in the first quarter of fiscal 1998
compared to 1997 due principally to the increase in product sales. Gross margins
decreased to 18% in the first quarter of fiscal 1998 compared to 25% in 1997.
This decrease was due primarily to lower margins on international sales in 1998
compared to 1997 and changes in product mix.

Total operating expenses were $2.6 million in the first quarter of fiscal 1998
compared to $3.2 million in 1997, a decrease of 18%. Research and development
costs decreased $.5 million or 33% due principally to lower process development
and startup costs associated with commercial scale-up of the Company's new WDG
manufacturing process for its new WDG formulation of its products and lower
personnel costs as a result of the shut down of a research lab in Israel.
Research and development costs are expected to continue to decrease in fiscal
1998 when compared to fiscal 1997. Fiscal 1997 included higher process
development costs as a result of the since resolved problem with the Company's
scale-up of its new WDG formulation. Also personnel costs are expected to
continue to decrease in the research and development area as the Company's
commitment to provide research services to Monsanto decreases and as the
Company's technology is commercialized, therefore requiring less activity in the
basic research area. Selling, general and administrative expenses were $1.7
million in the first quarter of fiscal 1998 compared to $1.8 million in 1997,
representing a decrease of $.1 million.

Net interest expense was $.1 million during the three months ended January 31,
1998 compared to net interest income of $.1 million in the comparable period of
1997 due to increased levels of long-term debt and decreased funds available for
investment.

Net income for the three months ended January 31, 1998 was $.8 million, compared
to a net loss of ($2.2) million for the same period in 1997. Basic and diluted
net income per share for the three months ended January 31, 1998 was $.09,
compared to net loss per share of ($.28) on weighted average shares outstanding
of 8.0 million and 7.8 million in the first quarter of 1998 and 1997,
respectively.

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. 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


                                       10

<PAGE>   13

SEASONALITY OF BUSINESS (CONTINUED)

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. In
addition, 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.

LIQUIDITY AND CAPITAL RESOURCES

At January 31, 1998, the Company had cash and liquid investments of $4.8
million, representing a net increase of $2.4 million from October 31, 1997. The
net increase was due to $2.6 million of cash provided by operations, offset by
$.1 million used for capital expenditures and $.1 million for repayment of
capital lease obligations.

The Company has financed its working capital needs primarily through private and
public offerings of equity securities, research revenues and license and other
fees from research and development alliances and product sales.

Through fiscal 1997, the Company had not generated positive cash flow from
operations in any fiscal year. The Company believes that its existing working
capital and cash flows generated in 1998 should be sufficient to meet its
capital and liquidity requirements for fiscal 1998 based on reduced spending
levels. The Company continues to pursue additional avenues to supplement its
working capital, including, among other things, through the possible sale of
assets. There is no assurance that such financing will be available on terms
acceptable to the Company or at all. 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 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 necessary to fund its strategic priorities. Over the long term, the
Company's liquidity is dependent on market acceptance of its products and
technology.


                                       11

<PAGE>   14

ASSETS, LIABILITIES AND STOCKHOLDERS' EQUITY

Accounts receivable decreased $.4 million due to certain shorter payment terms
on trade receivables. Inventory increased $.3 million at January 31, 1998 when
compared to October 31, 1997, the end of the Company's fiscal year, as a result
of building inventories for sales in the growing season. Accounts payable and
accrued expenses increased $.5 million due to an increase in payables
associated with the increase in inventory and timing of payments to vendors.
Deferred contract revenue increased $1.1 million at January 31, 1998 due to
amounts advanced under the Monsanto research and development agreement that are
expected to be earned through January 31, 1999.

FORWARD LOOKING STATEMENTS

The discussion set forth in this document contains forward looking statements
that involve 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 newly introduced products over the next several weeks and
months. These products, some of which utilize new formulations, 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 may not be successfully
incorporated into the manufacturing process in time to meet targeted sales
opportunities. Additional risks and uncertainties include: (i) the market
acceptance of the Company's current and newly introduced products; (ii) the
efficacy, pricing, ease of use and performance of the Company's products; (iii)
the successful development, registration, commercialization and marketing of
technologically advanced new products; (iv) the continued and uninterrupted
supply of the Company's products from third party toll manufacturers and the
continued financial viability of such manufacturers; (v) economic and
environmental considerations which impact agricultural crop production and
agricultural crop protection including the amount 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 (vi) the
ability of the Company to fund its strategic priorities through operations or
access to capital markets.


                                       12

<PAGE>   15

PART II - OTHER INFORMATION


Item 6(a)                  Exhibits

<TABLE>
<CAPTION>

Exhibit No.                Description
<S>                        <C>   
10.131                     Contract Manufacturing Agreement dated November 6, 
                           1997 by and between Ecogen Inc. and Archer-
                           Daniels-Midland Company.

10.132                     Amended and Restated Research and Development
                           Agreement dated January 30, 1998 by and between
                           Monsanto Company and Ecogen Inc.

27                         Financial Data Schedule
</TABLE>

                                       13

<PAGE>   16

                                   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 17, 1998


                                    ECOGEN INC.



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



                                    By:      /s/ MARY E. PAETZOLD
                                             -----------------------------------
                                             Mary E. Paetzold
                                             Vice President and Chief Financial 
                                             Officer


                                       14