<PAGE>





                        SECURITIES AND EXCHANGE COMMISSION 
                              Washington, D.C. 20549
 
                                   FORM 10-K/A
 
                  ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) 
                      OF THE SECURITIES EXCHANGE ACT OF 1934
 
 For the fiscal year ended March 31, 1997         Commission File Number 0-23252
 
                             IGEN International, Inc. 
-------------------------------------------------------------------------------
              (Exact name of registrant as specified in its charter)
 


                 DELAWARE                            94-2852543)
    (State or other jurisdiction of               (I.R.S. Employer 
      incorporation or organization)             Identification No.)


                   16020 INDUSTRIAL DRIVE, GAITHERSBURG, MD 20877 
-------------------------------------------------------------------------------
                (Address of principal executive offices) (Zip code) 

                                  (301) 984-8000 
-------------------------------------------------------------------------------
               (Registrant's telephone Number, including area code)
 
     Securities registered pursuant to Section 12(b) of the Act: NONE
 
     Securities registered pursuant to Section 12(g) of the Act:
 
                          Common Stock $0.001 par value 
                          ----------------------------- 
                                 (Title of Class)
 
    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 by check mark if disclosure of delinquent filers pursuant to Item
405 of Regulation S-K is not contained herein, and will not be contained to the
best of the registrants's knowledge, in definitive proxy or information
statements incorporated by reference in Part III of this Form 10-K/A or any
amendment to this Form 10-K/A.  ________
 
    The aggregate market value of the voting stock held by non-affiliates of the
Registrant as of June 17, 1997, computed by reference to the closing sale price
of such stock quoted on the Nasdaq National Market, was approximately
$59,109,800. For the purposes of this calculation, shares owned by officers,
directors and 5% shareholders known to the Registrant have been deemed to be
owned by affiliates.
 
    The number of shares outstanding of the Registrant's Common Stock as of June
17, 1997 was 15,006,017.
 
    DOCUMENTS INCORPORATED BY REFERENCE: None

<PAGE>



    IGEN International, Inc. ("IGEN" or the "Company") expects to reschedule 
the date of its annual meeting from September 9, 1997 to October 7, 1997 and 
therefore amends the following items of its Annual Report on Form 10-K for 
the fiscal year ending March 31, 1997. Each such item is set forth herein in 
its entirety, as amended. No exhibits are filed with this amendment.
 
                                    PART III
 
ITEM 10. DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT
 
Information as to Directors.

    The Board of Directors consists of six directors divided into three classes
designated as Class I, Class II and Class III, respectively. The term of office
of the Class I directors will expire at the next annual meeting of stockholders
and at that time Class I directors will be elected for a three-year term. The
terms of office of the Class II directors and Class III directors will expire at
the annual meetings of stockholders in 1998 and 1999, respectively, and their
successors will be elected for a three-year term.
 
    The following table sets forth the names of the members of the Board of
Directors as of July 18, 1997. Also set forth is certain other information with
respect to each such person's age, principal occupation or employment during the
past five years, the periods during which he has served as a director and
positions currently held with the Company. One Class II director position is
vacant.
 
<TABLE>
<CAPTION>
                                                      DIRECTOR                                     POSITIONS HELD
DIRECTORS                                   AGE         SINCE     EXPIRATION OF TERM              WITH THE COMPANY
--------------------------------------      ---      -----------  -------------------  --------------------------------------
<S>                                         <C>      <C>          <C>                  <C>
Robert Salsmans.......................       52          1995             1997         Director
Edward B. Lurier(1)(2)................       66          1987             1997         Director
Richard J. Massey, Ph.D...............       50          1990             1998         President, Chief Operating Officer and
                                                                                       Director
William J. O'Neill(1)(2)..............       55          1984             1999         Director
Samuel J. Wohlstadter.................       55          1982             1999         Chairman, Chief Executive Officer and
                                                                                       Director
</TABLE>
 
------------------------
 
(1) Member of Audit Committee.
(2) Member of Compensation Committee.

                                       2
<PAGE>
 
Set forth below is certain biographical information regarding the directors 
of the Company.
 
Class I Directors (term expires 1997)
 
    EDWARD B. LURIER is a General Partner of Gryphon Financial Partners, a
venture capital fund, and Chairman of Gryphon Management Co., Inc., a venture
capital firm, positions he has held since January 1986. Mr. Lurier has been a
Director of the Company since 1987. Mr. Lurier is also a Director of Energy
Biosystems Corp., a fossil fuel, biotechnology research and development company,
and several privately held companies.
 
    ROBERT R. SALSMANS has served as President and Chief Executive Officer of
Organon Teknika B.V., a business unit that is part of the Pharma group of Akzo
Nobel N.V., a holding company with high technology operating units in the
biotechnology, medical, and pharmaceutical industries, in the Netherlands, since
September 1994. From October 1993 through August 1994, Mr. Salsmans served as
Managing Director of Organon Teknika B.V. and from 1990 through September 1993,
he served as Managing Director of Organon International B.V. Mr. Salsmans sits
on the Board pursuant to an agreement between Organon Teknika entered into as
part of the long-term license agreement and stock purchase agreement between the
parties in May 1993. Mr. Salsmans has been a Director of the Company since 1995.
 
Class II Directors (term expires 1998)
 
    RICHARD J. MASSEY, Ph.D. is a founder of the Company, has been President and
Chief Operating Officer of the Company since February 1992, and has been a
Director of the Company since 1990. He served as Senior Vice President from 1985
to 1992. From 1981 until he joined IGEN in 1983, Dr. Massey was a faculty member
in the Microbiology and Immunology Department at Rush Medical Center in Chicago.
Prior to that, he was Senior Research Scientist at the National Cancer
Institute, Frederick Cancer Research Center.
 
Class III Directors (term expires 1999)

    WILLIAM J. O'NEILL has been a Director of the Company since 1984. He serves
as Executive Vice President and Chief Financial Officer of Polaroid Corporation,
a photographic equipment company, where he has been employed for more than 25
years.
 
    SAMUEL J. WOHLSTADTER is a founder of the Company and has been Chairman of
the Board and Chief Executive Officer since its formation in 1982. Mr.
Wohlstadter has been a venture capitalist for more than 20 years and has
experience in founding, supporting and managing high technology companies,
including Amgen Inc., a biopharmaceutical company, and Applied Biosystems, Inc.,
a medical and biological research products company. Mr. Wohlstadter is also
Chief Executive Officer of Hyperion Catalysis International, an advanced
materials company, which he founded in 1981, of Pro-Neuron, Inc., a drug
discovery company, which he founded in 1985, of Proteinix Corporation, a
development stage company organized to conduct research in intracellular
metabolic processes, which he founded in 1988, and of Pro-Virus, Inc., a drug
discovery company, which commenced operations in 1994.

                                       3
<PAGE>

INFORMATION AS TO EXECUTIVE OFFICERS.  The information with respect to the
Company's executive officers required under this item is incorporated by
reference to Part I of the Company's Form 10-K filed on July 11, 1997.
 
ITEM 11. EXECUTIVE COMPENSATION
 
COMPENSATION OF DIRECTORS
 
    Each non-employee director of the Company receives a per meeting attendance
fee of $1,000. In the fiscal year ended March 31, 1997, the total compensation
paid to non-employee directors (all directors except Mr. Wohlstadter and Dr.
Massey) was $11,000. In accordance with Company policy, all members of the Board
of Directors are eligible for reimbursement for their expenses incurred in
connection with attendance at Board meetings.
 
    On April 25, 1994, each non-employee director of the Company then sitting on
the Board of Directors was granted an option to purchase 10,000 shares of the
Company's Common Stock under the 1994 Non-Employee Directors' Stock Option Plan
at a purchase price of $8.75 per share (the closing sales price reported in the
NASDAQ National Market System on the day prior to the date of grant). Mr.
Salsmans was granted an option to purchase 10,000 shares of the Company's Common
Stock under the 1994 Non-Employee Directors' Stock Option Plan at a purchase
price of $6.25 when he joined the Board effective on August 25, 1995 (the
closing price reported in the NASDAQ National Market System on the day prior to
the date of grant). The options vest over a period of five years with one-fifth
of the option becoming exercisable one year from the date of grant and an
additional one-twentieth becoming exercisable every three months thereafter.
Such vesting is conditioned upon continued service as a director of the Company.
 
COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION
 
    The Compensation Committee of the Company was composed of three non-employee
directors in fiscal year 1997: Messrs. Lurier, O'Neill and Rehkaemper. None of
the foregoing persons is or has been an officer of the Company.

                                       4
<PAGE>

COMPENSATION OF EXECUTIVE OFFICERS
 
    The following table shows for the fiscal years ending March 31, 1997, 1996
and 1995, compensation awarded or paid to, or earned by the Company's Chief
Executive Officer and its other four most highly compensated executive officers
at March 31, 1997 (the "Named Executive Officers"):

                           SUMMARY COMPENSATION TABLE
 
<TABLE>
<CAPTION>
                                                                                       LONG-TERM
                                                           ANNUAL                     COMPENSATION                
                                                        COMPENSATION                     AWARDS                   
                                                        ------------                  ------------     OTHER ANNUAL
                                                           SALARY        BONUS          OPTIONS        COMPENSATION
NAME AND PRINCIPAL POSITION                    YEAR          ($)          ($)         (# SHARES)            ($)
-------------------------------------------  ---------  -------------  ---------  -------------------  -------------
<S>                                          <C>        <C>            <C>        <C>                  <C>
Samuel J. Wohlstadter                          1997        $260,000     $ ---           100,000              ---
Chairman and Chief Executive Officer           1996        $237,000     $50,000           ---                ---
                                               1995        $227,000     $40,000          62,500            $5,400(1)

Richard J. Massey, Ph.D.                       1997        $220,000     $ ---            80,000            $8,750(1)
President and Chief Operating Officer          1996        $200,000     $40,000           ---              $8,750(1)
                                               1995        $191,000     $35,000          50,000            $8,750(1)

George V. Migausky                             1997        $165,000     $ ---            50,000              ---
Vice President and Chief Financial             1996        $150,000     $30,000           ---                ---
Officer                                        1995        $142,000     $25,000          27,500              ---

Herman H. Spolders, Ph.D.                      1997        $187,500     $ ---            20,000              ---
Vice President, Business Development           1996        $172,250     $25,000           ---                ---
and Planning                                   1995        $150,000       ---             ---                ---

Robert Connelly                                1997        $140,000     $ ---            30,000              ---
Vice President, Marketing and Sales            1996        $127,000     $20,000           ---                ---
                                               1995        $120,000     $12,000          30,000              ---

</TABLE>
 
------------------------
(1) Consists of annual lease value of Company-provided automobile.
 
STOCK OPTION GRANTS AND EXERCISES
 
    The Company has granted options to its executive officers under its 1985
Stock Option Plan (the "1985 Plan") and its 1994 Stock Option Plan (the "1994
Plan") (collectively, the "Plans"). The 1994 Plan was adopted by the Board of
Directors in July 1994 to replace the 1985 Plan and was approved by the
stockholders in September 1994. 280,000 options were granted under the Plans to
the Named Executive Officers during the fiscal year ended March 31, 1997. The
Company is empowered to and from time to time does repurchase shares of Common
Stock in the open market for the purpose of making shares available for issuance
upon the exercise of options.
 
                                       5
<PAGE>

OPTION GRANTS IN LAST FISCAL YEAR
 
    The following table shows for the fiscal year ended March 31, 1997, certain
information regarding options granted to the Named Executive Officers.
 
                  Option Grants in Last Fiscal Year and Potential 
                 Realizable Value at Assumed Rate of Appreciation
 
<TABLE>
<CAPTION>
                                                                                                           POTENTIAL REALIZABLE
                                                                                                                 VALUE AT
                                                                                                           ASSUMED ANNUAL RATES
                                                                                                                 OF STOCK
                                                                                                          PRICE APPRECIATION FOR
                                             INDIVIDUAL GRANTS                                               OPTION TERM (2)
-------------------------------------------------------------------------------------------------------   ----------------------
                                               NUMBER OF       % OF TOTAL
                                               SECURITIES        OPTIONS
                                              UNDER-LYING     GRANTED TO      EXERCISE OR
                                                OPTIONS       EMPLOYEES IN     BASE PRICE    EXPIRATION
NAME                                         GRANTED (#)(1)    FISCAL YEAR       ($/SH)         DATE        5%($)       10%($)
-------------------------------------------  --------------  ---------------  -------------  -----------  ----------  ----------
<S>                                          <C>             <C>              <C>            <C>          <C>         <C>
Samuel J. Wohlstadter......................       100,000           32.26%         5.00         5/02/06   $  314,500  $  797,000
Richard J. Massey, Ph.D....................        80,000           25.81          5.00         5/02/06      251,500     637,500
George V. Migausky.........................        50,000           15.13          5.00         5/02/06      157,000     398,500
Herman H. Spolders, Ph.D...................        20,000            6.45          5.00         5/02/06       63,000     159,000
Robert Connelly............................        30,000            9.68          5.00         5/02/06       94,000     239,000
</TABLE>
 
------------------------
 
(1) These options were granted on May 3, 1996 under the 1994 Plan. Unless
    otherwise noted, the options granted each person vest over a period of five
    years with one-fifth of such person's options becoming exercisable one year
    from the date of grant and an additional one-twentieth of such options
    becoming exercisable every three months thereafter. The options expire ten
    years after the date of their grant. Under the 1994 Plan, the Compensation
    Committee or the Board of Directors may accelerate the time of vesting or
    time of exercise of any option granted. The Compensation Committee or the
    Board of Directors also has the authority, at any time and from time to
    time, to effect the downward repricing of any outstanding options and/or
    with the consent of the affected holders of options, the cancellation of any
    outstanding options and the grant of new options covering the same or
    different numbers of shares of Common Stock with an exercise price as of the
    new grant date of not less than: (i) 85% of the fair market value (as
    defined in the 1994 Plan) of the stock for options not intended to qualify
    as incentive stock options under Section 422 of the Internal Revenue Code of
    1986, as amended and the regulations promulgated thereunder, (ii) 100% of
    the fair market value for options intended to qualify as incentive stock
    options, and (iii) 110% of the fair market value for options held by a
    person holding more than 10% of the total combined voting power of all
    classes of stock of the Company or any affiliates. Subject to adjustments
    upon changes in stock, no person is eligible to be granted options covering
    more than 200,000 shares of Common Stock in any 12 month period.
 
(2) These amounts represent hypothetical gains that could be achieved for
    options if they are exercised at the end of the option term. These gains are
    based on assumed rates of stock price appreciation of 5% and 10% compounded
    annually from the date the options are granted to the end of the option
    term. Actual gains, if any, on stock option exercises are dependent on the
    future performance of the Company's Common Stock and the optionee's
    continued employment through the vesting period. There can be no assurance
    that the amounts reflected in this table will be achieved.
 
                                       6
<PAGE>

AGGREGATED OPTION EXERCISES IN LAST FISCAL YEAR, AND STOCK OPTION VALUES AT 
MARCH 31, 1997

    The following table sets forth information related to options exercised by
the Named Executive Officers during the fiscal year ending March 31, 1997 and
the number and value of options held at year end.
 
<TABLE>
<CAPTION>
                                                                        NUMBER OF SECURITIES
                                         SHARES                        UNDERLYING UNEXERCISED        VALUE OF UNEXERCISED
                                        ACQUIRED          VALUE              OPTIONS AT            IN-THE-MONEY OPTIONS AT
                                       ON EXERCISE      REALIZED         MARCH 31, 1997 (#)          MARCH 31, 1997 ($)
NAME                                       (#)             ($)       EXERCISABLE/UNEXERCISABLE(1) EXERCISABLE/UNEXERCISABLE(2)
-----------------------------------  ---------------  -------------  --------------------------   --------------------------
<S>                                  <C>              <C>            <C>                          <C>
Samuel J. Wohlstadter..............        -0-             -0-           469,375/113,125          $    288,762/$21,250
Richard J. Massey, Ph.D............        -0-             -0-           284,500/ 90,500               183,257/ 17,000
George V. Migausky.................        -0-             -0-            92,825/ 54,875                92,313/ 10,625
Herman H. Spolders, Ph.D...........        -0-             -0-            45,000/ 27,500                29,251/ 11,375
Robert Connelly....................        -0-             -0-            21,000/ 39,000                 1,125/  6,375
</TABLE>
 
------------------------
 
(1) Includes both "in-the-money" and "out-of-the-money" options. "In-the-money"
    options are options with exercise prices below the market price of the
    Company's Common Stock at March 31, 1997.
 
(2) Based on the closing price of the Company's Common Stock on March 31, 1997
    ($5.25) minus the exercise price.

                                       7
<PAGE>

ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT
 
    The following table sets forth, as of July 18, 1997 (except as otherwise
footnoted below), certain information regarding the ownership of the Company's
Common Stock of: (i) each current director; (ii) each nominee for director;
(iii) each of the Named Executive Officers; (iv) all executive officers and
directors of the Company as a group; and (v) all those known by the Company to
be beneficial owners of more than five percent (5%) of its outstanding Common
Stock.
 
<TABLE>
<CAPTION>
                                                    BENEFICIAL OWNERSHIP(1)
                                              ------------------------------------
NAME                                           NUMBER OF SHARES   PERCENT OF TOTAL
--------------------------------------------  -----------------  -----------------
<S>                                           <C>                <C>
Samuel J. and Nadine Wohlstadter(2).........       4,214,562              27.17%
  c/o IGEN International, Inc. 
  16020 Industrial Drive 
  Gaithersburg, MD 20877
Richard J. Massey, Ph.D. (3).....                  1,174,500               7.66%
   c/o IGEN International, Inc. 
   16020 Industrial Drive 
   Gaithersburg, MD 20877
Four Partners (4)......                            1,288,200               8.57%
   c/o Thomas J. Tisch 
   667 Madison Ave. 
   New York, NY 10021
Edward B. Lurier (5)........................         436,791               2.91%
George V. Migausky (6)......................         152,875               1.01%
Herman H. Spolders, Ph.D. (7)...............          52,250                *
Robert Connelly (8).........................          27,000                *
William J. O'Neill (9)......................          38,000                *
Robert R. Salsmans (10).....................           4,000                *
All directors and executive officers as a
group (10 persons)(11)......................       6,115,728              38.7%
</TABLE>
 
------------------------
 
*   Less than 1%
 
(1) This table is based upon information supplied by officers, directors and
    principal stockholders. Unless otherwise indicated in the notes to this
    table and subject to the community property laws where applicable, each of
    the stockholders named in this table has sole voting and investment power
    with respect to the shares shown as beneficially owned by him. Percentage of
    beneficial ownership is based on 15,026,917 shares of Common Stock 
    outstanding as of July 18, 1997, adjusted as required by rules promulgated 
    by the Securities and Exchange Commission.

                                       8
<PAGE>

(2) Includes 3,728,937 shares held by Mr. Wohlstadter and his wife and does not
    include 128,100 shares held by Mr. Wohlstadter's adult children. Also
    includes 485,625 shares issuable upon exercise of options held by Mr.
    Wohlstadter that are currently exercisable or exercisable within sixty days.
    Does not include 96,875 shares issuable upon exercise of options held by Mr.
    Wohlstadter that are subject to certain vesting conditions expiring ratably
    through May 2001.
 
(3) Includes 297,500 shares issuable upon exercise of options held by Mr. Massey
    that are currently exercisable or exercisable within sixty days. Does not
    include 77,500 shares issuable upon exercise of options held by Dr. Massey
    that are subject to certain vesting conditions expiring ratably through May
    2001.
 
(4) Based on information contained in the Schedule 13D filed with the Securities
    and Exchange Commission on January 8, 1997.
 
(5) Includes 6,500 shares issuable upon exercise of options held by Mr. Lurier
    that are currently exercisable or exercisable within sixty days. Also
    includes 418,091 shares held by Gryphon Ventures I, L.P. ("Gryphon
    Ventures"). Mr. Lurier is a general partner of Gryphon Ventures and may be
    deemed to own beneficially all of its shares. Does not include 3,500 shares
    issuable upon exercise of options held by Mr. Lurier that are subject to
    certain vesting conditions expiring ratably through April 1999.
 
(6) Includes 16,800 shares held by Mr. Migausky's minor children and 100,575
    shares issuable upon exercise of options held by Mr. Migausky that are
    currently exercisable or exercisable within sixty days. Does not include
    47,125 shares issuable upon exercise of options held by Mr. Migausky that
    are subject to certain vesting conditions expiring ratably through May 2001.
 
(7) Includes 52,250 shares issuable upon exercise of options held by Dr.
    Spolders that are currently exercisable or exercisable within sixty days.
    Does not include 20,250 shares issuable upon exercise of options held by Dr.
    Spolders that are subject to certain vesting conditions expiring ratably
    through May 2001.
 
(8) Includes 27,000 shares issuable upon exercise of options held by Mr.
    Connelly that are currently exercisable or exercisable within sixty days.
    Does not include 33,000 shares issuable upon exercise of options held by Mr.
    Connelly that are subject to certain vesting conditions expiring ratably
    through May 2001.
 
(9) Includes 6,500 shares issuable upon exercise of options held by Mr. O'Neill
    that are currently exercisable or exercisable within sixty days. Does not
    include 3,500 shares issuable upon exercise of options held by Dr. O'Neill
    that are subject to certain vesting conditions expiring ratably through
    April 1999.
 
(10) Includes 4,000 shares issuable upon exercise of options held by Mr.
    Salsmans that are currently exercisable or exercisable within sixty days.
    Does not include 6,000 shares issuable upon exercise of options held by Mr.
    Salsmans that are subject to certain vesting conditions expiring ratably
    through August 2000. Also excludes 346,135 shares held of record by Organon
    Teknika B.V. of which Mr. Salsmans disclaims beneficial ownership.

                                       9
<PAGE>
 
(11) Includes 995,700 shares issuable upon exercise of options that are
    currently exercisable or exercisable within sixty days. See also Notes (2),
    (3) and (5) through (10).
 
COMPLIANCE WITH SECTION 16(A) OF THE SECURITIES EXCHANGE ACT OF 1934
 
    Section 16(a) of the Securities Exchange Act of 1934 requires the 
Company's directors and executive officers, and persons who own more than ten 
percent of a registered class of the Company's equity securities, to file 
with the SEC initial reports of ownership and reports of changes in ownership 
of Common Stock and other equity securities of the Company. Officers, 
directors and greater than ten percent stockholders are required by SEC 
regulation to furnish the Company with copies of all Section 16(a) forms they 
file. Mr. Williams, a former officer of the Company, filed a Form 4 
(statement of Changes in Beneficial Ownership) late to report his exercise of 
stock options and his wife's disposition of shares in 1996.
 
ITEM 13. CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS
 
    The Company's Bylaws provide that the Company will indemnify its directors
and its officers, to the fullest extent permitted by Delaware law. The Company
is also empowered under its Bylaws to enter into indemnification contracts with
its directors and officers and to purchase insurance on behalf of any person
whom it is required or permitted to indemnify. Pursuant to these provisions, the
Company has entered into indemnity agreements with each of its directors and
executive officers and has obtained director and officer liability insurance in
the amount of $5,000,000.
 
    In addition, the Company's Certificate of Incorporation provides that the
Company's directors shall not be liable for monetary damages for breach of the
directors' fiduciary duty of care as a director, except liability for (i) any
breach of the director's duty of loyalty to the Corporation or its stockholders,
(ii) acts or omissions not in good faith or which involve intentional misconduct
or a knowing violation of law, (iii) under Section 174 of the Delaware General
Corporation Law, or (iv) any transaction from which a director derived an
improper personal benefit. If the Delaware General Corporation Law is amended
after approval by the stockholders of this Article to authorize corporate action
further eliminating or limiting personal liability of directors, then the
liability of a director shall be eliminated or limited to the fullest extent
permitted by the Delaware law.
 
    The Company has entered into a long-term license agreement and stock
purchase agreement with Organon Teknika in May 1993. Robert Salsmans, the
current President and Chief Executive Officer of Organon Teknika, is one of the
Company's directors. During fiscal 1997, the Company recorded product sales of
approximately $1.4 million with respect to Organon Teknika.
 
    During fiscal year 1995 the Company entered into agreements to develop 
and commercialize biomedical products utilizing advanced materials and a 
supply agreement with Hyperion Catalysis International ("Hyperion"). Messrs. 
Lurier, Massey and Wohlstadter are affiliated with Hyperion. During fiscal 
1996, the Company entered into a research and supply agreement under which 
the Company prepaid $500,000 to Hyperion to ensure itself of sufficient 
supplies of graphite fibrils.

                                       10
<PAGE>
 
    Pro-Virus, Inc. ("Pro-Virus"), Proteinix Corporation ("Proteinix"), and 
Pro-Neuron, Inc. ("Pro-Neuron") have a shared facilities arrangement and have 
shared certain equipment and administrative services with the Company since 
1994, 1992 and 1986, respectively. Pro-Virus, Proteinix and Pro-Neuron 
reimburse the Company for their relative share of the services received. In 
June 1995, the Company entered into a research and development agreement with 
Proteinix pursuant to which the Company has paid the contractual amount of 
$950,000 under the agreement. Mr. Wohlstadter is the principal stockholder 
and Chief Executive Officer of Pro-Virus, Proteinix and Pro-Neuron.
 
    During November 1995, the Company formed a Joint Venture for the 
development and commercialization of advanced diagnostic products utilizing a 
proprietary combination of multi-array technology together with the Company's 
ORIGEN technology. Products based on these technologies would be used for 
high throughput, multiparameter analysis for DNA sequencing. clinical 
chemistry and immunodiagnostics. The joint venture is named Meso Scale 
Diagnostics, LLC ("MSD"), and was formed together with Meso Scale 
Technologies, LLC ("MST"), a company based in Maryland. The Company has 
agreed to provide initial capital contributions to MSD of $5 million over 
time, in exchange for its ownership interest and to fund the organizational 
and certain ongoing (non-research) operating expenses of MSD. The Company 
will also participate in a collaborative research program. MST is a 
technology-based company established and operated by Jacob Wohlstadter, the 
son of Samuel J. Wohlstadter, the Chief Executive Officer of the Company. 
Nadine Wohlstadter, a member of MST, is the spouse of Samuel J. Wohlstadter. 
Over the forty month period beginning on June 1, 1996, Jacob Wohlstadter will 
receive an aggregate of approximately $420,000 from his employment at MSD and 
will receive $115,000 for each year he is employed at MSD thereafter. The 
Company has agreed to indemnify Jacob Wohlstadter against liability from the 
joint venture.
 
    The Company believes that all of the transactions set forth above were made
on terms no less favorable to the Company than could have been obtained from
unaffiliated third parties. All future transactions, including loans, between
the Company and its officers, directors and principal stockholders and their
affiliates will be approved by a majority of the Board of Directors, including a
majority of the independent and disinterested outside directors on the Board of
Directors, and will be on terms no less favorable to the Company than could be
obtained from unaffiliated third parties.
 
    Furthermore, the Company adopted in April 1988 a policy on conflicts of
interest requiring the Company's directors, officers and Scientific Advisory
Board members to provide detailed disclosure of any outside activities or
interest that might potentially conflict or appear to conflict with the
Company's best interests. The Company also adopted a policy on related party
transactions in January 1990 requiring review and approval by the Board of
Directors of transactions involving, among others, the Company's management,
principal stockholders or parties controlled by them when the value of the
transaction equals or exceeds $50,000 or its duration exceeds three months.
 
                                       11
<PAGE>
                                   SIGNATURES
 
Pursuant to the requirements of Section 13 or 15(d) of the Securities 
Exchange Act of 1934, the registrant has duly caused this report on Form 
10-K/A to be signed on its behalf by the undersigned thereunto duly 
authorized.
 
                              IGEN INTERNATIONAL, INC.

                              BY: /S/ SAMUEL J. WOHLSTADTER 
                                  ----------------------------
                                  CHIEF EXECUTIVE OFFICER 
DATED: JULY 29, 1997     

Pursuant to the requirements of the Securities Exchange Act of 1934, this 
report has been signed below by the following persons on behalf of the 
registrant and in the capacities and on the dates indicated.

          SIGNATURE                  TITLE                           DATE

  /s/ SAMUEL J. WOHLSTADTER        Chief Executive Officer       July 29, 1997
------------------------------     (Principal Executive   
    Samuel J. Wohlstadter          Officer); Director

 
    /s/ GEORGE V. MIGAUSKY         Vice President                July 29, 1997
------------------------------     and Chief Financial Officer
      George V. Migausky           (Principal Financing and
                                   Accounting Officer)


    /s/ RICHARD J. MASSEY          President, Chief Operating    July 29, 1997
------------------------------     Officer; Director
      Richard J. Massey


      /s/ EDWARD LURIER            Director                      July 29, 1997
------------------------------ 
        Edward Lurier


     /s/ WILLIAM O'NEILL           Director                      July 29, 1997
------------------------------
       William O'Neill


     /s/ ROBERT SALSMANS           Director                      July 29, 1997
------------------------------
       Robert Salsmans
 


By:/s/ SAMUEL J. WOHLSTADTER 
   ---------------------------
   Samuel J. Wohlstadter 
   Attorney-in-Fact
 
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