Exhibit 5

                           Wilmer, Cutler & Pickering
                              1600 Tysons Boulevard
                                   10th Floor
                          Tysons Corner, VA 22102-4826
                            Telephone: (703) 251-9700
                            Facsimile: (703) 251-9797


                                January 11, 2002


IGEN International, Inc.
16020 Industrial Drive
Gaithersburg, MD  20872


     Re: IGEN International, Inc. Registration Statement on Form S-8





Dear Ladies and Gentlemen:

         We have acted as counsel to IGEN International, Inc., a Delaware
corporation (the "Company"), in connection with a registration statement on Form
S-8 (the "Registration Statement") to be filed with the Securities and Exchange
Commission (the "Commission") under the Securities Act of 1933, as amended. The
Registration Statement relates to the registration of the shares of Common Stock
of the Company, par value $0.001 per share (the "Shares"), to be issued under
the Company's 2001 Broad Based Option Plan (the "Plan").

         For the purposes of this opinion, we have examined and relied upon the
following documents, as certified by the Secretary of the Company on January 10,
2002, as then being complete, accurate and in effect:

(1)      a copy of the 2001 Plan; and

(2)      a copy of the Resolutions of the Board of Directors dated July 26,
         2001 adopting the Plan.

         In our examination of the aforesaid documents, we have assumed the
genuiness of all signatures, the legal capacity of natural persons, the
authenticity of all documents submitted to us as originals, and the conformity
with the original documents of all documents submitted to us as certified,
telecopied, photostatic, or reproduced copies. We have assumed the accuracy of
the foregoing certifications, on which we are relying, and have made no
independent investigation thereof.

         Based solely upon the foregoing, and upon our examination of such
questions of law and statutes as we have considered necessary or appropriate,
and subject to the assumptions,




qualifications, limitations, and exceptions set forth in this letter, we are of
the opinion that: (a) the Shares have been lawfully and duly authorized; and
(b) such Shares will be validly issued, fully paid, and nonassessable upon
payment of the purchase price established under the 2001 Plan.

         This opinion is limited to the laws of the United States and the
General Corporation Law of Delaware. Although we do not hold ourselves out as
being experts in the Laws of Delaware, we have made an investigation of such
laws to the extent necessary to render our opinion. Our opinion is rendered only
with respect to the laws and the rules, regulations, and orders thereunder that
are currently in effect.

         We assume no obligation to advise you of any changes in the foregoing
subsequent to the delivery of this opinion. This opinion has been prepared for
your use in connection with the filing of the Registration Statement on or about
January 10, 2002, and should not be quoted in whole or in part or otherwise
referred to, nor otherwise be filed with or furnished to any governmental agency
or other person or entity, for any other purpose without our express prior
written consent.

         We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement.




                                   Sincerely,

                                    WILMER, CUTLER & PICKERING




                                    By: /s/ R. Scott Kilgore
                                    --------------------------------
                                    R. Scott Kilgore, a partner