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                                                                    EXHIBIT 10.4

                          REGISTRATION RIGHTS AGREEMENT

                  This Registration Rights Agreement (the "Agreement") is made
and entered into as of this 26th day of January, 2001 by and between Interleukin
Genetics, Inc., a Delaware corporation (the "Company"), and the "Investors"
named in that Purchase Agreement of even date herewith by and between the
Company and the Investors (the "Purchase Agreement").

         The parties hereby agree as follows:

         1.       Certain Definitions.

                  As used in this Agreement, the following terms shall have the
following meanings:

                  "Additional Registrable Securities" shall mean the shares of
Common Stock, if any, issued to the Investors pursuant to Section 7.1 of the
Purchase Agreement.

                  "Common Stock" shall mean the Company's Common Stock, par
value $0.001 per share.

                  "Investors" shall mean the purchasers identified in the
Purchase Agreement and any affiliate or permitted transferee of any Investor who
is a subsequent holder of any Warrants, Registrable Securities or Additional
Registrable Securities.

                  "Prospectus" shall mean the prospectus included in any
Registration Statement, as amended or supplemented by any prospectus supplement,
with respect to the terms of the offering of any portion of the Registrable
Securities or Additional Registrable Securities covered by such Registration
Statement and by all other amendments and supplements to the prospectus,
including post-effective amendments and all material incorporated by reference
in such prospectus.

                  "Register," "registered" and "registration" refer to a
registration made by preparing and filing a registration statement or similar
document in compliance with the 1933 Act (as defined below), and the declaration
or ordering of effectiveness of such registration statement or document.

                  "Registrable Securities" shall mean the shares of Common Stock
issued and issuable to the Investors pursuant to the Purchase Agreement (other
than additional shares of Common Stock issuable pursuant to Section 7.1 of the
Purchase Agreement) and issuable upon the exercise of the Warrants, and any
other securities issued or issuable with respect to or in exchange for
Registrable Securities.

                  "Registration Statement" shall mean any registration statement
of the Company filed under the 1933 Act that covers the resale of any of the
Registrable Securities or Additional Registrable Securities pursuant to the
provisions of this Agreement, amendments and
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supplements to such Registration Statement, including post-effective amendments,
all exhibits and all material incorporated by reference in such Registration
Statement.

                  "SEC" means the U.S. Securities and Exchange Commission.

                  "1933 Act" means the Securities Act of 1933, as amended, and
the rules and regulations promulgated thereunder.

                  "1934 Act" means the Securities Exchange Act of 1934, as
amended, and the rules and regulations promulgated thereunder.

                  "Warrants" mean the warrants to purchase shares of Common
Stock issued to the Investors pursuant to the Purchase Agreement, the form of
which is attached to the Purchase Agreement as Exhibit A.

         2.       Registration.

                           (a) Registration Statements.

                                    (i) Registrable Securities. Promptly
following the closing of the purchase and sale of Common Stock and Warrants
contemplated by the Purchase Agreement (the "Closing Date") (but no later than
thirty (30) days after the Closing Date), the Company shall prepare and file
with the SEC one Registration Statement on Form S-3 (or, if Form S-3 is not then
available to the Company, on such form of registration statement as is then
available to effect a registration for resale of the Registrable Securities,
subject to the Investors' consent), covering the resale of the Registrable
Securities in an amount equal to the number of shares of Common Stock issued to
the Investors on the Closing Date plus the number of shares of Common Stock
necessary to permit the exercise in full of the Warrants. Such Registration
Statement also shall cover, to the extent allowable under the 1933 Act and the
Rules promulgated thereunder (including Rule 416), such indeterminate number of
additional shares of Common Stock resulting from stock splits, stock dividends
or similar transactions with respect to the Registrable Securities. The Company
shall use its best efforts to obtain from each person who now has piggyback
registration rights a waiver of those rights with respect to the Registration
Statement. The securities of the Company owned by The Tail Wind Fund Ltd. and
those securities issued to The Tail Wind Fund Ltd. as a result of the
transactions contemplated by the Purchase Agreement shall be included in the
Registration Statement. The Registration Statement (and each amendment or
supplement thereto, and each request for acceleration of effectiveness thereof)
shall be provided in accordance with Section 3(c) to the Investors and their
counsel prior to its filing or other submission.

                                    (ii) Additional Registrable Securities. Upon
the written demand of any Investor and following the issuance of any additional
shares of Common Stock to such Investor pursuant to Section 7.1, of the Purchase
Agreement, the Company shall prepare and file with the SEC one Registration
Statement on Form S-3 (or, if Form S-3 is not then available to the Company, on
such form of registration statement as is then available to effect a
registration for resale of the Additional Registrable Securities, subject to the
Investor's consent)


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covering the resale of the Additional Registrable Securities in an amount equal
to the number of shares of Common Stock issued to such Investor. Such
Registration Statement also shall cover, to the extent allowable under the 1933
Act and the Rules promulgated thereunder (including Rule 416), such
indeterminate number of additional shares of Common Stock resulting from stock
splits, stock dividends or similar transactions with respect to the Additional
Registrable Securities. No securities held by a third party shall be included in
the Registration Statement without the consent of each Investor. The
Registration Statement (and each amendment or supplement thereto, and each
request for acceleration of effectiveness thereof) shall be provided in
accordance with Section 3(c) to the Investor and its counsel prior to its filing
or other submission.


                           (b) Expenses. The Company will pay all expenses
associated with each registration, including the Investors' reasonable expenses
in connection with the registration but excluding discounts, commissions, fees
of underwriters, selling brokers, dealer managers or similar securities industry
professionals.

                           (c) Effectiveness.

                                    (i) The Company shall use its best efforts
to have each Registration Statement declared effective as soon as practicable.
If (A) the Registration Statement covering Registrable Securities is not
declared effective by the SEC within three (3) months following the Closing
Date, or the Registration Statement covering Additional Registrable Securities
is not declared effective by the SEC within three (3) months following the
demand of an Investor relating to the Additional Registrable Securities covered
thereby, or with respect to either a Registration Statement which is subject to
full review by the SEC staff (which shall not include a "plain English" review),
within four (4) months following the Closing Date or demand, as the case may be
(each, a "Registration Date"), (B) after a Registration Statement has been
declared effective by the SEC, sales cannot be made pursuant to such
Registration Statement for any reason (including without limitation by reason of
a stop order, or the Company's failure to update the Registration Statement) but
except as excused pursuant to subparagraph (ii) below, or (C) the Common Stock
generally or the Registrable Securities specifically are not listed or included
for quotation on the Nasdaq National Market System, the Nasdaq Small Cap Market,
the New York Stock Exchange or the American Stock Exchange, then the Company
will make pro rata payments to each Investor, as liquidated damages and not as a
penalty, in an amount equal to 2% of the aggregate amount paid by such Investor
on the Closing Date to the Company for shares of Common Stock still held by such
Investor for any month or pro rata for any portion thereof following the
Registration Date during which any of the events described in (A) or (B) or (C)
above occurs and is continuing (the "Blackout Period"), provided, however, that
in the case of the events described in (A) or (B) above with respect only to the
Additional Registrable Securities, such penalty shall equal 2% of the aggregate
market value of such Additional Registrable Securities for the duration of the
Blackout Period. Each such payment shall be due and payable within five (5) days
of the end of each month (or ending portion thereof) of the Blackout Period.
Such payments shall be in partial compensation to the Investors, and shall not
constitute the Investors' exclusive remedy for such events. The Blackout Period
shall terminate upon (x) the effectiveness of the applicable Registration
Statement in the


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case of (A) and (B) above; (y) listing or inclusion of the Common Stock on the
Nasdaq National Market System, the Nasdaq Small Cap Market, the New York Stock
Exchange or the American Stock Exchange in the case of (C) above; and (z) in the
case of the events described in (A) or (B) above, the earlier termination of the
Registration Period (as defined in Section 3(a) below). The amounts payable as
liquidated damages pursuant to this paragraph shall be payable, at the option of
the Investors, in lawful money of the United States or in shares of Common Stock
at the Market Price (as defined in the Purchase Agreement), and amounts payable
as liquidated damages shall be paid monthly within two (2) business days of the
last day of each month following the commencement of the Blackout Period until
the termination of the Blackout Period. Amounts payable as liquidated damages
hereunder shall cease when an Investor no longer holds Warrants or Registrable
Securities, or Additional Registrable Securities, as applicable.

                                    (ii) For not more than ten (10) consecutive
trading days or for a total of not more than twenty (20) trading days in any
twelve (12) month period, the Company may delay the disclosure of material
non-public information concerning the Company, by terminating or suspending
effectiveness of any registration contemplated by this Section containing such
information, the disclosure of which at the time is not, in the good faith
opinion of the Company, in the best interests of the Company (an "Allowed
Delay"); provided, that the Company shall promptly (a) notify the Investors in
writing of the existence of (but in no event, without the prior written consent
of an Investor, shall the Company disclose to such Investor any of the facts or
circumstances regarding) material non-public information giving rise to an
Allowed Delay, and (b) advise the Investors in writing to cease all sales under
the Registration Statement until the end of the Allowed Delay. The duration of
the MFN Period provided for in the Purchase Agreement will be extended by the
number of days of any and all Allowed Delays.

                           (d) Underwritten Offering. If any offering pursuant
to a Registration Statement pursuant to Section 2(a) hereof involves an
underwritten offering, the Company shall have the right to select an investment
banker and manager to administer the offering, which investment banker or
manager shall be reasonably satisfactory to the Investors.

         3. Company Obligations. The Company will use its best efforts to effect
the registration of the Registrable Securities and Additional Registrable
Securities in accordance with the terms hereof, and pursuant thereto the Company
will, as expeditiously as possible:

                           (a) use its best efforts to cause such Registration
Statement to become effective and to remain continuously effective for a period
that will terminate upon the earlier of (i) the date on which all Registrable
Securities or Additional Registrable Securities, as the case may be, covered by
such Registration Statement, as amended from time to time, have been sold, and
(ii) the date on which all Registrable Securities or Additional Registrable
Securities, as the case may be, may be sold pursuant to Rule 144(k) (the
"Registration Period");

                           (b) prepare and file with the SEC such amendments and
post-effective amendments to the Registration Statement and the Prospectus as
may be necessary to keep the Registration Statement effective for the period
specified in Section 3(a) and to comply with the provisions of the 1933 Act and
the 1934 Act with respect to the distribution of all Registrable


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Securities and Additional Registrable Securities; provided that, at least five
(5) business days prior to the filing of a Registration Statement or Prospectus,
or any amendments or supplements thereto, the Company will furnish to the
Investors copies of all documents proposed to be filed, which documents will be
subject to the comments of the Investors, which must be received within such
five (5) business day period;

                           (c) permit counsel designated by the Investors to
review each Registration Statement and all amendments and supplements thereto no
fewer than seven (7) days prior to their filing with the SEC and not file any
document to which such counsel reasonably objects;

                           (d) furnish to the Investors and their legal counsel
(i) promptly after the same is prepared and publicly distributed, filed with the
SEC, or received by the Company, one copy of any Registration Statement and any
amendment thereto, each preliminary prospectus and Prospectus and each amendment
or supplement thereto, and each letter written by or on behalf of the Company to
the SEC or the staff of the SEC, and each item of correspondence from the SEC or
the staff of the SEC, in each case relating to such Registration Statement
(other than any portion of any thereof which contains information for which the
Company has sought confidential treatment), and (ii) such number of copies of a
Prospectus, including a preliminary prospectus, and all amendments and
supplements thereto and such other documents as each Investor may reasonably
request in order to facilitate the disposition of the Registrable Securities and
Additional Registrable Securities owned by such Investor;

                           (e) in the event the Company selects an underwriter
for the offering, the Company shall enter into and perform its reasonable
obligations under an underwriting agreement, in usual and customary form,
including, without limitation, customary indemnification and contribution
obligations, with the underwriter of such offering;

                           (f) if required by the underwriter, or if any
Investor is described in the Registration Statement as an underwriter, the
Company shall furnish, on the effective date of the Registration Statement, on
the date that Registrable Securities or Additional Registrable Securities, as
applicable, are delivered to an underwriter, if any, for sale in connection with
the Registration Statement and at periodic intervals thereafter from time to
time on request, (i) an opinion, dated as of such date, from independent legal
counsel representing the Company for purposes of such Registration Statement, in
form, scope and substance as is customarily given in an underwritten public
offering, addressed to the underwriter and the Investors and (ii) a letter,
dated such date, from the Company's independent certified public accountants in
form and substance as is customarily given by independent certified public
accountants to underwriters in an underwritten public offering, addressed to the
underwriter and the Investors;

                           (g) make effort to prevent the issuance of any stop
order or other suspension of effectiveness and, if such order is issued, obtain
the withdrawal of any such order at the earliest possible moment;

                           (h) furnish to each Investor at least five copies of
the Registration Statement and any post-effective amendment thereto, including
financial statements and schedules by air mail within two business days of the
effective date thereof;


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                           (i) prior to any public offering of Registrable
Securities or Additional Registrable Securities, use its reasonable best efforts
to register or qualify or cooperate with the Investors and their counsel in
connection with the registration or qualification of such Registrable Securities
or Additional Registrable Securities, as applicable, for offer and sale under
the securities or blue sky laws of such jurisdictions requested by the Investor
and do any and all other reasonable acts or things necessary or advisable to
enable the distribution in such jurisdictions of the Registrable Securities or
Additional Registrable Securities covered by the Registration Statement;

                           (j) cause all Registrable Securities or Additional
Registrable Securities covered by a Registration Statement to be listed on each
securities exchange, interdealer quotation system or other market on which
similar securities issued by the Company are then listed;

                           (k) immediately notify the Investors, at any time
when a Prospectus relating to the Registrable Securities or Additional
Registrable Securities is required to be delivered under the Securities Act,
upon discovery that, or upon the happening of any event as a result of which,
the Prospectus included in such Registration Statement, as then in effect,
includes an untrue statement of a material fact or omits to state any material
fact required to be stated therein or necessary to make the statements therein
not misleading in the light of the circumstances then existing, and at the
request of any such holder, promptly prepare and furnish to such holder a
reasonable number of copies of a supplement to or an amendment of such
Prospectus as may be necessary so that, as thereafter delivered to the
purchasers of such Registrable Securities or Additional Registrable Securities,
as applicable, such Prospectus shall not include an untrue statement of a
material fact or omit to state a material fact required to be stated therein or
necessary to make the statements therein not misleading in the light of the
circumstances then existing; and

                           (l) otherwise use its best efforts to comply with all
applicable rules and regulations of the SEC under the 1933 Act and the 1934 Act,
take such other actions as may be reasonably necessary to facilitate the
registration of the Registrable Securities and Additional Registrable
Securities, if applicable, hereunder; and make available to its security
holders, as soon as reasonably practicable, but not later than the Availability
Date (as defined below), an earnings statement covering a period of at least
twelve months, beginning after the effective date of each Registration
Statement, which earnings statement shall satisfy the provisions of Section
11(a) of the 1933 Act (for the purpose of this subsection 3(l), "Availability
Date" means the 45th day following the end of the fourth fiscal quarter that
includes the effective date of such Registration Statement, except that, if such
fourth fiscal quarter is the last quarter of the Company's fiscal year,
"Availability Date" means the 90th day after the end of such fourth fiscal
quarter).

         4. Due Diligence Review; Information. The Company shall make available,
during normal business hours, for inspection and review by the Investors,
advisors to and representatives of the Investors (who may or may not be
affiliated with the Investors and who are reasonably acceptable to the Company),
any underwriter participating in any disposition of Common Stock on behalf of
the Investors pursuant to the Registration Statement or amendments or
supplements


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thereto or any blue sky, NASD or other filing, all financial and other records,
all SEC Documents and other filings with the SEC, and all other corporate
documents and properties of the Company as may be reasonably necessary for the
purpose of such review, and cause the Company's officers, directors and
employees, within a reasonable time period, to supply all such information
reasonably requested by the Investors or any such representative, advisor or
underwriter in connection with such Registration Statement (including, without
limitation, in response to all questions and other inquiries reasonably made or
submitted by any of them), prior to and from time to time after the filing and
effectiveness of the Registration Statement for the sole purpose of enabling the
Investors and such representatives, advisors and underwriters and their
respective accountants and attorneys to conduct initial and ongoing due
diligence with respect to the Company and the accuracy of the Registration
Statement.


                  The Company shall not disclose material nonpublic information
to the Investors, or to advisors to or representatives of the Investors, unless
prior to disclosure of such information the Company identifies such information
as being material nonpublic information and provides the Investors, such
advisors and representatives with the opportunity to accept or refuse to accept
such material nonpublic information for review. The Company may, as a condition
to disclosing any material nonpublic information hereunder, require the
Investors' advisors and representatives to enter into a confidentiality
agreement (including an agreement with such advisors and representatives
prohibiting them from trading in Common Stock during such period of time as they
are in possession of material nonpublic information) in form reasonably
satisfactory to the Company and the Investors. Nothing herein shall require the
Company to disclose material nonpublic information to the Investors or their
advisors or representatives.

         5.       Obligations of the Investors.

                           (a) Each Investor shall furnish in writing to the
Company such information regarding itself, the Registrable Securities or
Additional Registrable Securities, as applicable, held by it and the intended
method of disposition of the Registrable Securities or Additional Registrable
Securities, as applicable, held by it, as shall be reasonably required to effect
the registration of such Registrable Securities or Additional Registrable
Securities, as applicable, and shall execute such documents in connection with
such registration as the Company may reasonably request. At least fifteen (15)
business days prior to the first anticipated filing date of any Registration
Statement, the Company shall notify each Investor of the information the Company
requires from such Investor if such Investor elects to have any of the
Registrable Securities or Additional Registrable Securities included in the
Registration Statement. An Investor shall provide such information to the
Company at least five (5) business days prior to the first anticipated filing
date of such Registration Statement if such Investor elects to have any of the
Registrable Securities or Additional Registrable Securities included in the
Registration Statement.

                           (b) Each Investor, by its acceptance of the
Registrable Securities and Additional Registrable Securities, if any, agrees to
cooperate with the Company as reasonably requested by the Company in connection
with the preparation and filing of a Registration Statement hereunder, unless
such Investor has notified the Company in writing of its election to


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exclude all of its Registrable Securities or Additional Registrable Securities,
as applicable, from the Registration Statement.

                           (c) In the event the Company, at the request of the
Investors, determines to engage the services of an underwriter, such Investor
agrees to enter into and perform its obligations under an underwriting
agreement, in usual and customary form, including, without limitation, customary
indemnification and contribution obligations, with the managing underwriter of
such offering and take such other actions as are reasonably required in order to
expedite or facilitate the dispositions of the Registrable Securities or
Additional Registrable Securities, as applicable.

                           (d) Each Investor agrees that, upon receipt of any
notice from the Company of the happening of any event rendering a Registration
Statement no longer effective, such Investor will immediately discontinue
disposition of Registrable Securities or Additional Registrable Securities
pursuant to the Registration Statement covering such Registrable Securities or
Additional Registrable Securities, until the Investor's receipt of the copies of
the supplemented or amended prospectus filed with the SEC and declared effective
and, if so directed by the Company, the Investor shall deliver to the Company
(at the expense of the Company) or destroy (and deliver to the Company a
certificate of destruction) all copies in the Investor's possession of the
prospectus covering the Registrable Securities or Additional Registrable
Securities, as applicable, current at the time of receipt of such notice.

                           (e) No Investor may participate in any third party
underwritten registration hereunder unless it (i) agrees to sell the Registrable
Securities or Additional Registrable Securities, as applicable, on the basis
provided in any underwriting arrangements in usual and customary form entered
into by the Company, (ii) completes and executes all questionnaires, powers of
attorney, indemnities, underwriting agreements and other documents reasonably
required under the terms of such underwriting arrangements, and (iii) agrees to
pay its pro rata share of all underwriting discounts and commissions and any
expenses in excess of those payable by the Company pursuant to the terms of this
Agreement.

         6.       Indemnification.

                           (a) Indemnification by Company. The Company agrees to
indemnify and hold harmless, to the fullest extent permitted by law the
Investors, each of their officers, directors, partners and employees and each
person who controls the Investors (within the meaning of the 1933 Act) against
all losses, claims, damages, liabilities, costs (including, without limitation,
reasonable attorney's fees) and expenses imposed on such person caused by (i)
any untrue or alleged untrue statement of a material fact contained in any
Registration Statement, Prospectus or any preliminary prospectus or any
amendment or supplement thereto or any omission or alleged omission to state
therein a material fact required to be stated therein or necessary to make the
statements therein not misleading, except insofar as the same are based upon any
information furnished in writing to the Company by such Investors, expressly for
use therein, or (ii) any violation by the Company of any federal, state or
common law, rule or regulation applicable to the Company in connection with any
Registration Statement, Prospectus or any preliminary prospectus, or any
amendment or supplement thereto, and shall reimburse in


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accordance with subparagraph (c) below, each of the foregoing persons for any
legal and any other expenses reasonably incurred in connection with
investigating or defending any such claims. The foregoing is subject to the
condition that, insofar as the foregoing indemnities relate to any untrue
statement, alleged untrue statement, omission or alleged omission made in any
preliminary prospectus or Prospectus that is eliminated or remedied in any
Prospectus or amendment or supplement thereto, the above indemnity obligations
of the Company shall not inure to the benefit of any indemnified party if a copy
of such corrected Prospectus or amendment or supplement thereto had been made
available to such indemnified party and was not sent or given by such
indemnified party at or prior to the time such action was required of such
indemnified party by the 1933 Act and if delivery of such Prospectus or
amendment or supplement thereto would have eliminated (or been a sufficient
defense to) any liability of such indemnified party with respect to such
statement or omission. Indemnity under this Section 5(a) shall remain in full
force and effect regardless of any investigation made by or on behalf of any
indemnified party and shall survive the permitted transfer of the Registrable
Securities and Additional Registrable Securities.

                           (b) Indemnification by Holder. In connection with any
registration pursuant to the terms of this Agreement, each Investor will furnish
to the Company in writing such information as the Company reasonably requests
concerning the holders of Registrable Securities and Additional Registrable
Securities or the proposed manner of distribution for use in connection with any
Registration Statement or Prospectus and agrees, severally but not jointly, to
indemnify and hold harmless, to the fullest extent permitted by law, the
Company, its directors, officers, employees, stockholders and each person who
controls the Company (within the meaning of the 1933 Act) against any losses,
claims, damages, liabilities and expense (including reasonable attorney's fees)
resulting from or arising out of (i) any failure by the Investor to comply with
the prospectus delivery requirements or (ii) any untrue statement of a material
fact or any omission of a material fact required to be stated in the
Registration Statement or Prospectus or preliminary prospectus or amendment or
supplement thereto or necessary to make the statements therein not misleading,
to the extent, but only to the extent that such untrue statement or omission is
contained in any information furnished in writing by such Investor to the
Company specifically for inclusion in such Registration Statement or Prospectus
or amendment or supplement thereto and that such information was substantially
relied upon by the Company in preparation of the Registration Statement or
Prospectus or any amendment or supplement thereto. In no event shall the
liability of an Investor be greater in amount than the dollar amount of the
proceeds (net of all expense paid by such Investor and the amount of any damages
such holder has otherwise been required to pay by reason of such untrue
statement or omission) received by such Investor upon the sale of the
Registrable Securities or Additional Registrable Securities included in the
Registration Statement giving rise to such indemnification obligation.

                           (c) Conduct of Indemnification Proceedings. Any
person entitled to indemnification hereunder shall (i) give prompt notice to the
indemnifying party of any claim with respect to which it seeks indemnification
and (ii) permit such indemnifying party to assume the defense of such claim with
counsel reasonably satisfactory to the indemnified party; provided that any
person entitled to indemnification hereunder shall have the right to employ
separate counsel and to participate in the defense of such claim, but the fees
and expenses of such counsel


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shall be at the expense of such person unless (a) the indemnifying party has
agreed to pay such fees or expenses, or (b) the indemnifying party shall have
failed to assume the defense of such claim and employ counsel reasonably
satisfactory to such person or (c) in the reasonable judgment of any such
person, based upon written advice of its counsel, a conflict of interest exists
between such person and the indemnifying party with respect to such claims (in
which case, if the person notifies the indemnifying party in writing that such
person elects to employ separate counsel at the expense of the indemnifying
party, the indemnifying party shall not have the right to assume the defense of
such claim on behalf of such person); and provided, further, that the failure of
any indemnified party to give notice as provided herein shall not relieve the
indemnifying party of its obligations hereunder, except to the extent that such
failure to give notice shall materially adversely affect the indemnifying party
in the defense of any such claim or litigation. It is understood that the
indemnifying party shall not, in connection with any proceeding in the same
jurisdiction, be liable for fees or expenses of more than one separate firm of
attorneys at any time for all such indemnified parties. No indemnifying party
will, except with the consent of the indemnified party, consent to entry of any
judgment or enter into any settlement that does not include as an unconditional
term thereof the giving by the claimant or plaintiff to such indemnified party
of a release from all liability in respect of such claim or litigation.

                           (d) Contribution. If for any reason the
indemnification provided for in the preceding paragraphs (a) and (b) is
unavailable to an indemnified party or insufficient to hold it harmless, other
than as expressly specified therein, then the indemnifying party shall
contribute to the amount paid or payable by the indemnified party as a result of
such loss, claim, damage or liability in such proportion as is appropriate to
reflect the relative fault of the indemnified party and the indemnifying party,
as well as any other relevant equitable considerations. No person guilty of
fraudulent misrepresentation within the meaning of Section 11(f) of the 1933 Act
shall be entitled to contribution from any person not guilty of such fraudulent
misrepresentation. In no event shall the contribution obligation of a holder of
Registrable Securities or Additional Registrable Securities be greater in amount
than the dollar amount of the proceeds (net of all expenses paid by such holder
and the amount of any damages such holder has otherwise been required to pay by
reason of such untrue or alleged untrue statement or omission or alleged
omission) received by it upon the sale of the Registrable Securities or
Additional Registrable Securities giving rise to such contribution obligation.

         7.       Miscellaneous.

                           (a) Amendments and Waivers. This Agreement may be
amended only by a writing signed by the parties hereto. The Company may take any
action herein prohibited, or omit to perform any act herein required to be
performed by it, only if the Company shall have obtained the written consent to
such amendment, action or omission to act, of each Investor.

                           (b) Notices. All notices and other communications
provided for or permitted hereunder shall be made as set forth in Section 9.4 of
the Purchase Agreement.

                           (c) Assignments and Transfers by Investors. This
Agreement and all the rights and obligations of the Investors hereunder may not
be assigned or transferred to any


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<PAGE>   11
transferee or assignee except to an affiliate or permitted transferee of an
Investor who is a subsequent holder of any Warrants, Registrable Securities or
Additional Registrable Securities.

                           (d) Assignments and Transfers by the Company. This
Agreement may not be assigned by the Company without the prior written consent
of each Investor, except that without the prior written consent of the
Investors, but after notice duly given, the Company shall assign its rights and
delegate its duties hereunder to any successor-in-interest corporation, and such
successor-in-interest shall assume such rights and duties, in the event of a
merger or consolidation of the Company with or into another corporation or the
sale of all or substantially all of the Company's assets.

                           (e) Benefits of the Agreement. The terms and
conditions of this Agreement shall inure to the benefit of and be binding upon
the respective permitted successors and assigns of the parties. Nothing in this
Agreement, express or implied, is intended to confer upon any party other than
the parties hereto or their respective successors and assigns any rights,
remedies, obligations, or liabilities under or by reason of this Agreement,
except as expressly provided in this Agreement.

                           (f) Counterparts. This Agreement may be executed in
two or more counterparts, each of which shall be deemed an original, but all of
which together shall constitute one and the same instrument.

                           (g) Titles and Subtitles. The titles and subtitles
used in this Agreement are used for convenience only and are not to be
considered in construing or interpreting this Agreement.

                           (h) Severability. If one or more provisions of this
Agreement are held to be unenforceable under applicable law, such provision
shall be excluded from this Agreement and the balance of this Agreement shall be
interpreted as if such provision were so excluded and shall be enforceable in
accordance with its terms to the fullest extent permitted by law.

                           (i) Further Assurances. The parties shall execute and
deliver all such further instruments and documents and take all such other
actions as may reasonably be required to carry out the transactions contemplated
hereby and to evidence the fulfillment of the agreements herein contained.

                           (j) Entire Agreement. This Agreement is intended by
the parties as a final expression of their agreement and intended to be a
complete and exclusive statement of the agreement and understanding of the
parties hereto in respect of the subject matter contained herein. This Agreement
supersedes all prior agreements and understandings between the parties with
respect to such subject matter.

                           (k) Applicable Law. This Agreement shall be governed
by, and construed in accordance with, the laws of the State of New York without
regard to principles of conflicts of law.


                                      -11-
<PAGE>   12
                  IN WITNESS WHEREOF, the parties have executed this
Registration Rights Agreement as of the date first written above.

The Company:                             INTERLEUKIN GENETICS, INC.


                                         By:_______________________________
                                         Name: ____________________________
                                         Title: _____________________________


The Investors:                           SPECIAL SITUATIONS FUND III, L.P.

                                         By:_______________________________
                                         Name: ____________________________
                                         Title: _____________________________


                                         SPECIAL SITUATIONS CAYMAN FUND, L.P.

                                         By:_______________________________
                                         Name: ____________________________
                                         Title: _____________________________


                                         SPECIAL SITUATIONS PRIVATE EQUITY
                                         FUND, L.P.

                                         By:_______________________________
                                         Name: ____________________________
                                         Title: _____________________________


                                      -12-