SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549


                                  FORM 8-A/A

               FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
                   PURSUANT TO SECTION 12(b) OR 12(g) OF THE
                        SECURITIES EXCHANGE ACT OF 1934

                                   AMENDMENT

                           IGEN INTERNATIONAL, INC.
            (Exact name of registrant as specified in its charter)

                  Delaware                                   94-2852543
          (State of incorporation                           (IRS Employer
              or organization)                           Identification No.)

           16020 Industrial Drive                                20877
           Gaithersburg, Maryland                             (Zip Code)
  (address of principal executive offices)


Securities to be registered pursuant to Section 12(b) of the Act:

                                                     Name of exchange on
           Title of each Class                      which each class is to
           to be so registered                      to be registered
           None                                     Not applicable

          If this form relates to the registration of a class of securities
pursuant to Section 12(b) of the Exchange Act and is effective pursuant to
General Instruction A.(c), check the following box. [ ]

          If this form relates to the registration of a class of securities
pursuant to Section 12(g) of the Exchange Act and is effective pursuant to
General Instruction A.(d), check the following box. [ ]

          Securities Act registration statement file number to which this form
relates:

          ...............(if applicable)

Securities to be registered pursuant to Section 12(g) of the Act:

                         Preferred Share Purchase Rights
                                (Title of Class)



                                                                             2


          This Registration Statement on Form 8-A/A amends and restates the
Registration Statement on Form 8-A filed with the Securities and Exchange
Commission by IGEN International, Inc. (the "Registrant") on December 10,
1996.

ITEM 1.  DESCRIPTION OF REGISTRANT'S SECURITIES TO BE REGISTERED.

          On July 24, 2003, the Registrant entered into an Agreement and Plan
of Merger (the "Merger Agreement") with Roche Holding Ltd ("Roche"), 66
Acquisition Corporation II ("Merger Sub") and IGEN Integrated Healthcare, LLC
("Newco"). Simultaneously with the execution of the Merger Agreement, the
following agreements were entered into: a Restructuring Agreement between the
Registrant and Newco, a Post-Closing Covenants Agreement among the Registrant,
Roche and Newco, a Tax Allocation Agreement among the Registrant, Roche,
Merger Sub and Newco, an Ongoing Litigation Agreement among the Registrant,
Roche Diagnostics GmbH ("Roche Diagnostics"), Roche Diagnostics Corporation,
Meso Scale Diagnostics, LLC. ("MSD") and Meso Scale Technologies, LLC.
("MST"), a Release and Agreement among the Registrant, Newco, Hyperion
Catalysis International, Wellstat Biologics Corporation, Wellstat Therapeutics
Corporation, Proteinix Corporation and Integrated Chemical Synthesizers, Inc.
and a Global Consent and Agreement among the Registrant, Roche, Newco, MSD,
MST, Jacob Wohlstadter and JW Consulting Services L.L.C. (collectively,
together with the Merger Agreement, the "Transaction Agreements"), and a
License Agreement between the Registrant and IGEN LS, LLC ("IGEN LS"), an
Improvements License Agreement between the Registrant and Roche Diagnostics, a
Covenants Not to Sue among Newco, MSD, MST, Roche Diagnostics, Roche and IGEN
LS, a License Agreement (Human IVD, Veterinary IVD, HLA Typing, Paternity, DNA
Manufacturing and Plasma Testing) among Newco, F. Hoffmann-La Roche Ltd
("FHLR"), Roche Diagnostics and Roche Molecular Systems, Inc. and a License
Agreement (Human IVD Services and Animal Diagnostic Services) among Newco,
FHLR, Roche Diagnostics and Roche Molecular Systems, Inc. (collectively, the
"Commercial Agreements"). The Transaction Agreements provide, among other
things, that (i) prior to the effective time (the "Effective Time") of the
merger contemplated by the Merger Agreement, the Registrant will transfer
certain assets and liabilities to Newco or one or more of Newco's subsidiaries
and (ii) at the Effective Time, Merger Sub will merge with and into the
Registrant.

          In connection with the Transaction Agreements and the Commercial
Agreements, on July 24, 2003, the Registrant entered into the Amendment to
Rights Agreement with EquiServe Trust Company, N.A. (successor to The First
National Bank of Boston) (the "Rights Agreement Amendment"). The Rights
Agreement Amendment amends the Rights Agreement dated as of November 6, 1996,
between the Registrant and The First National Bank of Boston (the "Rights
Agreement"), to (i) render the Rights Agreement inapplicable to the
transactions contemplated by the Transaction Agreements and the Commercial
Agreements and (ii) provide that (A) neither Roche nor any of its affiliates
or associates will become an Acquiring Person (described below) by reason of
any of the Transaction Agreements, the Commercial Agreements or any of the
transactions contemplated thereby, (B) a Distribution Date (described below)
will not occur by reason of, among other things, the Registrant's entering
into the Transaction Agreements and the Commercial Agreements, the public
announcement of such fact or the consummation of the transactions contemplated
by the Transaction Agreements or the Commercial Agreements, (C) a Shares
Acquisition Date (described below) will not occur by reason of, among other
things, the Registrant's entering into the Transaction Agreements and the
Commercial Agreements, the public announcement of such fact on the
consummation of the transactions contemplated by the Transaction Agreements or
the Commercial Agreements, and (D) the Rights (described below) shall expire
immediately prior to the Effective Time.

          In the event the Merger Agreement is terminated prior to the
Effective Time, the Rights Agreement Amendment shall be null and void.

SUMMARY OF THE RIGHTS AGREEMENT AS AMENDED

          Each preferred share purchase right (a "Right") entitles the
registered holder to purchase from the Registrant one one-hundredth of a share
of Series A Junior Participating Preferred Stock, par value $0.001 per share
(the "Preferred Shares"), of the Registrant at a price of $65.00 per one
one-hundredth of a Preferred Share (the "Purchase Price"), subject to
adjustment. The description and terms of the Rights are set forth in the
Rights Agreement.



                                                                             3

          Initially, the Rights will be evidenced by the stock certificates
representing Common Shares then outstanding, and no separate Right
Certificates, as defined, will be distributed. Until the earlier to occur of
(i) the Shares Acquisition Date (described below) or (ii) 10 business days (or
such later date as may be determined by action of the Board of Directors prior
to such time as any person or group of affiliated persons becomes an Acquiring
Person) following the commencement of, or announcement of an intention to
make, a tender offer or exchange offer, the consummation of which would result
in the beneficial ownership by a person or group of 15% or more of the
outstanding Common Shares (the earlier of such dates being called the
"Distribution Date"), the Rights will be evidenced, with respect to any of the
Common Share certificates outstanding as of the Record Date, by such Common
Share certificate with a copy of this Summary of Rights attached thereto.

          The Shares Acquisition Date is the first date of public announcement
that a person or group (other than (A) the Registrant, (B) a majority-owned
subsidiary of the Registrant, (C) any employee benefit plan of the Registrant
or any majority-owned subsidiary of the Registrant, (D) any entity holding
Common Shares for or pursuant to the terms of any such plan and (E) Mr. Samuel
J. Wohlstadter, his affiliates and associates, his heirs, and any trust or
foundation to which he has transferred or may transfer Common Shares of the
Registrant ("Samuel Wohlstadter" and each of the persons listed in (A) through
(E) above, an "Excluded Person")) has become the beneficial owner of 15% or
more of the outstanding Common Shares (an "Acquiring Person"). Notwithstanding
the foregoing, neither Roche nor any of its affiliates shall become an
Acquiring Person as a result of (i) the adoption, approval, execution or
delivery of any of the Transaction Agreements or the Commercial Agreements,
(ii) the public announcement of such adoption, approval, execution or delivery
or (iii) the consummation of the transactions contemplated or permitted by the
terms of the Transaction Agreements or the Commercial Agreements. In addition,
(i) the adoption, approval, execution or delivery of any of the Transaction
Agreements or the Commercial Agreements, (ii) the public announcement of such
adoption, approval, execution or delivery or (iii) the consummation of the
transaction contemplated or permitted by the terms of the Transaction
Agreements or the Commercial Agreements shall not, in each case, individually
or collectively, be deemed to constitute a Shares Acquisition Date,
Distribution Date or any other separation of the Rights from the underlying
Common Shares, nor entitle or permit the holders of the Rights to exercise the
Rights or otherwise affect the rights of the holders of the Rights.

          The Rights Agreement provides that, until the Distribution Date (or
earlier redemption or expiration of the Rights), the Rights will be
transferred with and only with the Common Shares. Until the Distribution Date
(or earlier redemption or expiration of the Rights), new Common Share
certificates issued after the Record Date upon transfer or new issuance of
Common Shares will contain a notation incorporating the Rights Agreement by
reference. Until the Distribution Date (or earlier redemption or expiration of
the Rights) the surrender or transfer of any certificates for Common Shares
outstanding as of the Record Date will also constitute the transfer of the
Rights associated with the Common Shares represented by such certificate. As
soon as practicable following the Distribution Date, separate certificates
evidencing the Rights ("Right



                                                                             4

Certificates") will be mailed to holders of record of the Common Shares
as of the close of business on the Distribution Date and such separate Right
Certificates alone will evidence the Rights.

          The Rights are not exercisable until the Distribution Date. The
Rights will expire prior to the earliest of (i) November 6, 2006 (the "Final
Expiration Date"), (ii) the time at which the Rights are redeemed as described
below, (iii) the time at which the Rights are exchanged as described below and
(iv) immediately prior to the Effective Time.

          The Purchase Price payable, and the number of Preferred Shares or
other securities or property issuable, upon exercise of the Rights are subject
to adjustment from time to time to prevent dilution (i) in the event of a
stock dividend on, or a subdivision, combination or reclassification of, the
Preferred Shares, (ii) upon the grant to holders of the Preferred Shares of
certain rights or warrants to subscribe for or purchase Preferred Shares at a
price, or securities convertible into Preferred Shares with a conversion
price, less than the then-current market price of the Preferred Shares or
(iii) upon the distribution to holders of the Preferred Shares of evidences of
indebtedness or assets (excluding regular periodic cash dividends paid out of
earnings or retained earnings or dividends payable in Preferred Shares) or of
subscription rights or warrants (other than those referred to above).

          The number of outstanding Rights and the number of one
one-hundredths of a Preferred Share issuable upon exercise of each Right are
also subject to adjustment in the event of a stock split of the Common Shares
or a stock dividend on the Common Shares payable in Common Shares or
subdivisions, consolidations or combinations of the Common Shares occurring,
in any such case, prior to the Distribution Date.

          Preferred Shares purchasable upon exercise of the Rights will not be
redeemable. Each Preferred Share will be entitled to a minimum preferential
quarterly dividend payment of $l per share but will be entitled to an
aggregate dividend of 100 times the dividend declared per Common Share. In the
event of liquidation, the holders of the Preferred Shares will be entitled to
a minimum preferential liquidation payment of $100 per share but will be
entitled to an aggregate payment of 100 times the payment made per Common
Share. Each Preferred Share will have 100 votes, voting together with the
Common Shares. Finally, in the event of any merger, consolidation or other
transaction in which Common Shares are exchanged, each Preferred Share will be
entitled to receive 100 times the amount received per Common Share. These
rights are protected by customary anti-dilution provisions. Because of the
nature of the Preferred Shares' dividend, liquidation and voting rights, the
value of the one one-hundredth interest in a Preferred Share purchasable upon
exercise of each Right should approximate the value of one Common Share. The
Preferred Shares rank junior to all other series of the Registrant's preferred
stock.

          In the event that the Registrant is acquired by any person, other
than Samuel Wohlstadter, in a merger or other business combination transaction
or 50% or more of its consolidated assets or earning power are sold to any
person other than Samuel Wohlstadter, proper provision will be made so that
each holder of a Right will thereafter have the right to receive, upon the
exercise thereof at the then-current exercise price of the Right, that number
of shares of common stock of the acquiring company which at the time of such
transaction will have a market value of two times the exercise price of



                                                                             5

the Right. In the event that any person or group of affiliated or associated
persons becomes an Acquiring Person, proper provision shall be made so that
each holder of a Right, other than Rights beneficially owned by the Acquiring
Person (which will thereafter be void), will thereafter have the right to
receive upon exercise that number of Common Shares having a market value of
two times the exercise price of the Right. Notwithstanding the foregoing, the
occurrence of (i) the adoption, approval, execution or delivery of any of the
Transaction Agreements or the Commercial Agreements, (ii) the public
announcement of such adoption, approval, execution or delivery or (iii) the
consummation of the transactions contemplated or permitted by the terms of any
of the Transaction Agreements or the Commercial Agreements shall not, in each
case, individually or collectively, result in a separation of the Rights from
the underlying Common Shares, nor entitle or permit the holders of the Rights
to exercise the Rights or otherwise affect any rights of the holders of the
Rights, including giving the holders of the Rights the right to acquire
securities of any party to the Transaction Agreements or the Commercial
Agreements or any party to the transactions contemplated or permitted by the
terms of the Transaction Agreements or the Commercial Agreements.

          At any time after any Person becomes an Acquiring Person and prior
to the acquisition by such person or group of 50% or more of the outstanding
Common Shares, the Board of Directors of the Registrant may exchange the
Rights (other than Rights owned by such person or group which will have become
void), in whole or in part, at an exchange ratio of one Common Share, or one
one-hundredth of a Preferred Share (or of a share of a class or series of the
Registrant's preferred stock having equivalent rights, preferences and
privileges), per Right (subject to adjustment).

          With certain exceptions, no adjustment in the Purchase Price will be
required until cumulative adjustments require an adjustment of at least 1% in
such Purchase Price. No fractional Preferred Shares will be issued (other than
fractions which are integral multiples of one one-hundredth of a Preferred
Share, which may, at the election of the Registrant, be evidenced by
depositary receipts) and in lieu thereof, an adjustment in cash will be made
based on the market price of the Preferred Shares on the last trading day
prior to the date of exercise.

          At any time prior to the earliest of (i) the time a person has
become an Acquiring Person, or (ii) the Final Expiration Date, the Board of
Directors of the Registrant may redeem the Rights in whole, but not in part,
at a price of $0.01 per Right (the "Redemption Price"). Following the
expiration of the above periods, the Rights become nonredeemable. Immediately
upon any redemption of the Rights, the right to exercise the Rights will
terminate and the only right of the holders of Rights will be to receive the
Redemption Price.

          The terms of the Rights may be amended by the Board of Directors of
the Registrant without the consent of the holders of the Rights, including an
amendment to lower certain thresholds described above to any percentage which
is (i) greater than the largest percentage of the outstanding Common Shares
then known to the Registrant to be beneficially owned by any person or group
of affiliated or associated persons (other than an excepted person) and (ii)
not less than 10%, except that from and after such time as any person or group
of affiliated or associated persons becomes an Acquiring Person no, such
amendment may adversely affect the interests of the holders of the Rights.

          Until a Right is exercised, the holder thereof, as such, will have
no rights as a stockholder of the Registrant, including, without limitation,
the right to vote or to receive dividends.




                                                                             6

ITEM 2.  EXHIBITS.

Exhibit No.     Description
-----------     -----------

1.1             Specimen Right Certificate (incorporated herein by reference
                to Exhibit 1.1 of the Registrant's Registration Statement on
                Form 8-A filed December 10, 1996, File No. 000-23252).

2.1             Rights Agreement dated as of November 6, 1996, between the
                Registrant and The First National Bank of Boston (incorporated
                herein by reference to Exhibit 2.1 of the Registrant's
                Registration Statement Form 8-A filed December 10, 1996,
                File No. 000-23252).

3.1             Amendment to Rights Agreement dated as of July 24, 2003,
                between the Registrant and EquiServe Trust Company, N.A.
                (successor to The First National Bank of Boston).




                                                                             7

                                   SIGNATURE

          Pursuant to the requirements of Section 12 of the Securities
Exchange Act of 1934, the Registrant has duly caused this registration
statement to be signed on its behalf by the undersigned, thereto duly
authorized.

Date: July 24, 2003

                                       IGEN INTERNATIONAL, INC.

                                       By: /s/ Richard J. Massey
                                           ----------------------------
                                           Name:   Richard J. Massey
                                           Title:  President and Chief
                                                   Operating Officer




                                                                             8

                                  EXHIBIT INDEX


Exhibit No.     Description
-----------     -----------

1.1             Specimen Right Certificate (incorporated herein by reference to
                Exhibit 1.1 of the Registrant's Registration Statement on
                Form 8-A filed December 10, 1996, File No. 000-23252).

2.1             Rights Agreement dated as of November 6, 1996, between the
                Registrant and The First National Bank of Boston (incorporated
                herein by reference to Exhibit 2.1 of the Registrant's
                Registration Statement Form 8-A filed December 10, 1996,
                File No. 000-23252).

3.1             Amendment to Rights Agreement dated as of July 24, 2003,
                between the Registrant and EquiServe Trust Company, N.A.
                (successor to The First National Bank of Boston).









                          AMENDMENT TO RIGHTS AGREEMENT


                         AMENDMENT (this "Amendment") dated as of July 24,
                    2003, to the Rights Agreement (the "Rights Agreement")
                    dated as of November 6, 1996, between IGEN International,
                    Inc., a Delaware corporation (the "Company"), and
                    EQUISERVE TRUST COMPANY, N.A. (successor to The First
                    National Bank of Boston, a national banking association)
                    (the "Rights Agent").

          WHEREAS the Company and the Rights Agent have previously entered
into the Rights Agreement;

          WHEREAS, pursuant to Section 27 of the Rights Agreement, the Company
may from time to time supplement or amend the Rights Agreement in accordance
with the provisions of Section 27 thereof; and

          WHEREAS all acts and things necessary to make this Amendment a valid
agreement have been done and performed and the execution and delivery of this
Amendment by the Company and the Rights Agent have been in all respects duly
authorized by the Company and the Rights Agent.

          NOW, THEREFORE, in consideration of the foregoing and the mutual
agreements set forth in the Rights Agreement and this Amendment, the parties
hereto hereby agree as follows:

          SECTION 1. AMENDMENTS OF SECTION 1. (a) The definition of "ACQUIRING
PERSON" in Section 1(a) of the Rights Agreement hereby is amended by inserting
the following at the end of such section:

          Notwithstanding any other provision in this Rights Agreement to the
     contrary, none of Roche Holding Ltd, a joint stock company organized
     under the laws of Switzerland ("R Company"), nor any of its Affiliates or
     Associates shall become an Acquiring Person as a result of the (i)
     adoption, approval, execution or delivery of any of the Transaction
     Agreements, Commercial Agreements or Stockholders Agreement, (ii) public
     announcement of such adoption, approval, execution or delivery or (iii)
     consummation of the transactions contemplated or permitted by the terms
     of the Transaction Agreements, Commercial Agreements or Stockholders
     Agreement.

          (b) The definition of "SHARES ACQUISITION DATE" in Section 1(o) of
the Rights Agreement hereby is amended by (i) inserting the word "(i)"
immediately before the words "(y) of the last sentence of Section 1(a) hereof"
in such Section, (ii) inserting the words "second to" immediately before the
words "last sentence of Section 1(a) hereof,", (iii) inserting the words "or
(ii) the last sentence of Section 1(a) hereof" immediately after the words
"last sentence of Section 1(a) hereof" and




(iv) inserting the words "in each case" immediately before the words "no
Shares Acquisition Date shall be deemed to have occurred".

          (c) Section 1 of the Rights Agreement hereby is amended by inserting
the following paragraphs at the end thereof:

               (s) "Commercial Agreements" shall have the meaning set forth in
          Section 10.03 of the Merger Agreement.

               (t) "Merger Agreement" shall mean the Agreement and Plan of
          Merger dated as of July 24, 2003 (as the same may be amended or
          supplemented), among R Company, 66 Acquisition Corporation II, the
          Company and IGEN Integrated Healthcare, LLC.

               (u) "Stockholders Agreement" shall have the meaning set forth
          in the recitals to the Merger Agreement.

               (v) "Transaction Agreements" shall have the meaning set forth
          in Section 10.03 of the Merger Agreement.

          SECTION 2. AMENDMENT OF SECTION 3. Section 3 of the Rights Agreement
hereby is amended by inserting the following words at the end of the first
sentence thereof:

     ; PROVIDED, HOWEVER, that notwithstanding any other provision in this
     Rights Agreement to the contrary, the occurrence of (i) the adoption,
     approval, execution or delivery of any of the Transaction Agreements,
     Commercial Agreements or Stockholders Agreement, (ii) the public
     announcement of such adoption, approval, execution or delivery or (iii)
     the consummation of the transactions contemplated or permitted by the
     terms of any of the Transaction Agreements, Commercial Agreements or
     Stockholders Agreement shall not, in each case, individually or
     collectively, constitute a Distribution Date.

          SECTION 3. AMENDMENT OF SECTION 7. Section 7(a) of the Rights
Agreement hereby is amended by deleting the word "or" immediately preceding
clause (iii) thereof and by inserting the following new phrase immediately
following clause (iii) thereof:

          or (iv) immediately prior to the Effective Time (as defined in the
     Merger Agreement).

          SECTION 4. ADDITION OF A NEW SECTION 35. The Rights Agreement hereby
is amended by inserting the following new Section 35 immediately after Section
34 thereof:




          SECTION 35. EXCLUDED TRANSACTIONS. Notwithstanding any other
     provision of this Agreement, the occurrence of (i) the adoption,
     approval, execution or delivery of any of the Transaction Agreements,
     Commercial Agreements or Stockholders Agreement, (ii) the public
     announcement of such adoption, approval, execution or delivery or (iii)
     the consummation of the transactions contemplated or permitted by the
     terms of any of the Transaction Agreements, Commercial Agreements or
     Stockholders Agreement shall not, in each case, individually or
     collectively, constitute a Shares Acquisition Date, Distribution Date, or
     any other separation of the Rights from the underlying Common Shares, nor
     entitle or permit the holders of the Rights to exercise the Rights or
     otherwise affect any rights of the holders of the Rights, including
     giving the holders of the Rights the right to acquire securities of any
     party to the Transaction Agreements, Commercial Agreements or
     Stockholders Agreement or any party to the transactions contemplated or
     permitted by the terms of the Transaction Agreements, Commercial
     Agreements or Stockholders Agreement.

          SECTION 5. EFFECTIVE DATE. This Amendment shall be effective as of
the date hereof. In the event that the Merger Agreement is terminated prior to
the Effective Time (as defined in the Merger Agreement), this Amendment shall
be null and void.

          SECTION 6. FULL FORCE AND EFFECT. Except as expressly amended
hereby, the Rights Agreement shall continue in full force and effect in
accordance with the provisions thereof on the date hereof.

          SECTION 7. GOVERNING LAW. This Amendment shall be deemed to be a
contract made under the laws of the State of Delaware and for all purposes
shall be governed by and construed in accordance with the laws of such State
applicable to contracts to be made and performed entirely within such State.

          SECTION 8. COUNTERPARTS. This Amendment may be executed in any
number of counterparts and each of such counterparts shall for all purposes be
deemed to be an original, and all such counterparts shall together constitute
but one and the same instrument.

          SECTION 9. DESCRIPTIVE HEADINGS. Descriptive headings of the several
Sections of this Amendment are inserted for convenience only and shall not
control or affect the meaning or construction of any of the provisions hereof.

          SECTION 10. RIGHTS AGREEMENT AS AMENDED. Upon the effectiveness of
this amendment, the term "Rights Agreement" as used in the Rights Agreement
shall refer to the Rights Agreement as amended hereby.





          IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
be duly executed and attested, all as of the day and year first above written.

                                            IGEN INTERNATIONAL, INC.,


                                            by: /s/ Richard Massey
                                                ---------------------------
                                                Name:  Richard Massey
                                                Title: President and Chief
                                                       Operating Officer


Attest:


/s/ Daniel Abdun-Nabi
---------------------------------
Name:  Daniel Abdun-Nabi
Title: General Counsel


                                            EQUISERVE TRUST COMPANY, N.A.,



                                            by: /s/ Dennis V. Moccia
                                                ---------------------------
                                                Name:  Dennis V. Moccia
                                                Title: Managing Director

Attest:


/s/ Dana Arlock
---------------------------------
Name:  Dana Arlock
Title: Risk Analyst