<PAGE>


    As filed with the Securities and Exchange Commission on December 20, 2000

                                                          REGISTRATION NO. 333-

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D. C. 20549


                                    FORM S-8
                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933


                        GENAISSANCE PHARMACEUTICALS, INC.
             (Exact Name of Registrant as Specified in its Charter)

         DELAWARE                                               06-1338846
      (State or Other                                        (I.R.S. Employer
Jurisdiction of Incorporation)                              Identification No.)

                                FIVE SCIENCE PARK
                          NEW HAVEN, CONNECTICUT 06511
                                 (203) 773-1450
                    (Address of Principal Executive Offices)


                        EMPLOYEE STOCK PURCHASE PLAN 2000
                            (Full Title of the Plan)

                                   KEVIN RAKIN
                      President and Chief Financial Officer
                        Genaissance Pharmaceuticals, Inc.
                                Five Science Park
                          New Haven, Connecticut 06511
                                 (203) 773-1450
            (Name, Address and Telephone Number of Agent for Service)

                                 with copies to:

                              MICHAEL LYTTON, ESQ.
                               Palmer & Dodge LLP
                                One Beacon Street
                           Boston, Massachusetts 02108
                                 (617) 573-0100

                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>

----------------------------------------- ------------------ -------------------- -------------------- ----------------
                                                              Proposed maximum     Proposed maximum       Amount of
Title of each class of securities to be     Amount to be     offering price per   aggregate offering    registration
               registered                    registered           share (1)            price (1)             fee
<S>                                       <C>                <C>                  <C>                  <C>
----------------------------------------- ------------------ -------------------- -------------------- ----------------

Common Stock, $0.001 par value            250,000 shares           $21.9375           $5,484,375             $1,448
----------------------------------------- ------------------ -------------------- -------------------- ----------------

</TABLE>

(1)  Estimated solely for the purpose of determining the registration fee and
     computed pursuant to Rule 457(h)(1). The proposed maximum offering price
     per share indicated equals the average of the high and low sale price of
     the Common Stock as reported by the Nasdaq National Market on December 15,
     2000.

<PAGE>

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

         The following documents previously filed with the Securities and
Exchange Commission are incorporated by reference herein and shall be deemed as
part hereof:

         (a)      the prospectus contained in our registration statement on
                  Form S-1 (File No. 333-35314) filed under the Securities Act
                  of 1933, as amended, (the "Securities Act") on August 1, 2000;

         (b)      our quarterly reports on Form 10-Q for the quarters ended June
                  30, 2000 and September 30, 2000 filed under the Securities
                  Exchange Act of 1934, as amended, (the "Exchange Act") on
                  September 1, 2000 and November 14, 2000, respectively (File
                  No. 000-30981); and

         (c)      the description of our common stock contained in our
                  Registration Statement on Form 8-A filed on July 11, 2000,
                  including any amendment or report filed hereafter for the
                  purpose of updating such description.

         All documents filed after the date of this registration statement
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act of 1934 and
prior to the filing of a post-effective amendment that indicates that all shares
of common stock offered hereunder have been sold or that deregisters all shares
of common stock remaining unsold shall be deemed to be incorporated by reference
herein and to be a part hereof from the date of the filing of such reports and
documents.

ITEM 4.  DESCRIPTION OF SECURITIES.

         Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

         Not applicable.

ITEM 6.  INDEMNIFICATION OF OFFICERS AND DIRECTORS.

         Section 145 of the Delaware General Corporation Law provides that a
corporation may indemnify any person who was or is a party or is threatened to
be made a party to any threatened, pending or completed action, suit or
proceeding, whether civil, criminal, administrative or investigative, other than
an action by or in the right of the corporation, by reason of the fact that the
person is or was a director, officer, employee or agent of the corporation or is
or was serving at the corporation's request as a director, officer, employee or
agent of another corporation, partnership, joint venture, trust or other
enterprise, against expenses, including attorneys' fees, judgments, fines and
amounts paid in settlement actually and reasonably incurred by the person in
connection with the action, suit or proceeding if the person acted in good faith
and in a manner the person reasonably believed to be in or not opposed to the
best interests of the corporation, and, with respect to any criminal action or
proceeding, had no reasonable cause to believe the person's conduct was
unlawful. The power to indemnify applies to actions brought by or in the right
of the corporation as well, but only to the extent of expenses, including
attorneys' fees but excluding judgments, fines and amounts paid in settlement,
actually and reasonably incurred by the person in connection with the defense or
settlement of the action or suit. In these actions no indemnification shall be
made in the event of any adjudication of negligence or misconduct in the
performance of his duties to the corporation, unless a court believes that in
light of all the circumstances indemnification should apply.

         Article V of Genaissance's Amended and Restated By-laws provides that
Genaissance shall, to the extent legally permitted, indemnify each person who
was or is a party or is threatened to be made a party to any threatened, pending
or completed action, suit or proceeding by reason of the fact that he is or was,
or has agreed to become, a director or officer of Genaissance, or is or was
serving, or has agreed to serve, at the request of Genaissance, as a director,
officer or trustee of, or in a similar capacity with, another corporation,
partnership, joint venture, trust or other enterprises. The indemnification
provided for in Article V is expressly not exclusive of any other rights to


                                       2

<PAGE>

which those seeking indemnification may be entitled under any law, agreement or
vote of stockholders or disinterested directors or otherwise, and shall inure to
the benefit of the heirs, executors and administrators of such persons.

         Section 145(g) of the Delaware General Corporation Law and Article V of
Amended and Restated By-laws of Genaissance provide that the company shall have
the power to purchase and maintain insurance on behalf of its officers,
directors, employees and agents, against any liability asserted against and
incurred by such persons in any such capacity.

         Genaissance has entered into indemnification agreements with each of
its directors and has obtained insurance covering its directors and officers
against losses and insuring Genaissance against certain of its obligations to
indemnify its directors and officers.

         Section 102(b)(7) of the General Corporation Law of the State of
Delaware provides that a corporation may eliminate or limit the personal
liability of a director to the corporation or its stockholders for monetary
damages for breach of fiduciary duty as a director, provided that such
provisions shall not eliminate or limit the liability of a director (i) for any
breach of the director's duty of loyalty to the corporation or its stockholders,
(ii) for acts or omissions not in good faith or which involve intentional
misconduct or a knowing violation of law, (iii) under Section 174 of the General
Corporation Law of the State of Delaware, or (iv) for any transaction from which
the director derived an improper personal benefit. No such provision shall
eliminate or limit the liability of a director for any act or omission occurring
prior to the date when such provision becomes effective.

         Pursuant to the Delaware General Corporation Law, Section 6 of Article
FIFTH of the Amended and Restated Certificate of Incorporation of Genaissance
eliminates a director's personal liability for monetary damages to Genaissance
and its stockholders for breach of fiduciary duty as a director, except in
circumstances involving a breach of the director's duty of loyalty to
Genaissance or its stockholders, acts or omissions not in good faith,
intentional misconduct, knowing violations of the law, liability under Section
174 of the Delaware Corporation Law or any transaction from which the director
derived an improper personal benefit.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

         Not applicable.

ITEM 8.  EXHIBITS.

         See Exhibit Index immediately following signature pages.

ITEM 9.  UNDERTAKINGS.

         (a)      The undersigned registrant hereby undertakes:

                  (1)      To file, during any period in which offers or sales
are being made, a post-effective amendment to this registration statement:

                           (i)      To include any prospectus required by
Section 10 (a)(3) of the Securities Act of 1933;

                           (ii)     To reflect in the prospectus any facts or
events arising after the effective date of this registration statement (or the
most recent post-effective amendment thereof) which, individually or in the
aggregate, represents a fundamental change in the information set forth in this
registration statement;

                           (iii)    To include any material information with
respect to the plan of distribution not previously disclosed in this
registration statement or any material change to such information in this
registration statement; provided, however, that paragraphs (a) (1) (i) and (a)
(1) (ii) do not apply if the information required to be included in a
post-effective amendment by those paragraphs is contained in periodic reports
filed by the Registrant pursuant to Section 13 or Section 15(d) of the Exchange
Act of 1934 that are incorporated by reference in this Registration Statement.


                                       3

<PAGE>

                  (2) That, for the purpose of determining any liability under
the Securities Act of 1933, each such post-effective amendment shall be deemed
to be a new registration statement relating to the securities offered therein,
and the offering of such securities at that time shall be deemed to be the
initial bona fide offering thereof.

                  (3) To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

         (b) The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act of 1934 that is incorporated by reference in this registration
statement shall be deemed to be a new registration statement relating to the
securities offered therein and the offering of such securities at that time
shall be deemed to be initial bona fide offering thereof.

         (c) Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the registrant pursuant to the provisions referred to in Item 6
hereof, or otherwise, the registrant has been advised that in the opinion of the
Securities and Exchange Commission such indemnification is against public policy
as expressed in the Securities Act of 1933 and is, therefore, unenforceable. In
the event that a claim for indemnification against such liabilities (other than
the payment by the registrant of expenses incurred or paid by a directors,
officer or controlling person of the registrant in the successful defense of any
action, suit or proceeding) is asserted by such director, officer, or
controlling person in connection with the securities being registered, the
registrant will, unless in the opinion of its counsel the matter has been
settled by controlling precedent, submit to a court of appropriate jurisdiction
the question whether such indemnification by it is against public policy as
expressed in the Securities Act of 1933 and will be governed by the final
jurisdiction of such issue.


                                       4

<PAGE>

                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has duly caused this Registration Statement to be
signed on its behalf by the undersigned, thereunto duly authorized, in the Town
of New Haven, Connecticut on December 20, 2000.

                                   GENAISSANCE PHARMACEUTICALS, INC.

                                   By:  /s/ Kevin Rakin
                                        ---------------------------------------
                                        Kevin Rakin
                                        President and Chief Financial Officer

                                POWER OF ATTORNEY

         We, the undersigned officers and directors of Genaissance
Pharmaceuticals, Inc., hereby severally constitute and appoint Gualberto Ruano,
M.D., Ph.D., Kevin Rakin and Michael Lytton and each of them singly, our true
and lawful attorneys-in-fact, with full power to them in any and all capacities,
to sign any amendments to this Registration Statement on Form S-8 (including any
post-effective amendments thereto), and to file the same, with exhibits thereto
and other documents in connection therewith, with the Securities and Exchange
Commission, hereby ratifying and confirming all that each of said
attorneys-in-fact may do or cause to be done by virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities and on the dates indicated.

<TABLE>
<CAPTION>

SIGNATURE                                     TITLE                                            DATE
<S>                                           <C>                                              <C>
/S/ GUALBERTO RUANO                           Chief Executive Officer and Director             December 20, 2000
------------------------------------          (Principal Executive Officer)
Gualberto Ruano, M.D., Ph.D.

/S/ KEVIN RAKIN                               Chief Financial Officer (Principal Financial     December 20, 2000
------------------------------------          and Accounting Officer) and Director
Kevin Rakin


/S/ JURGEN DREWS                              Chairman of the Board                            December 20, 2000
------------------------------------
Jurgen Drews, M.D.


/S/ GERHARD LAUR                              Director                                         December 20, 2000
------------------------------------
Gerhard Laur, M.D.


/S/ HARRY H. PENNER, JR.                      Director                                         December 20, 2000
------------------------------------
Harry H. Penner, Jr., J.D.


SETH RUDNICK                                  Director                                         December 20, 2000
------------------------------------
Seth Rudnick, M.D.


STEFAN RYSER                                  Director                                         December 20, 2000
------------------------------------
Stefan Ryser, Ph.D.


CHRISTOPHER WRIGHT                            Director                                         December 20, 2000
------------------------------------
Christopher Wright

</TABLE>

                                       5

<PAGE>

                                  EXHIBIT INDEX

    EXHIBIT
     NUMBER               DESCRIPTION

      4.1         Amended and Restated Certificate of Incorporation of
                  Genaissance Pharmaceuticals, Inc. Filed as Exhibit 3.2 to our
                  Registration Statement on Form S-1 (File No. 333-35314) and
                  incorporated herein by reference.

      4.2         Amended and Restated By-laws of Genaissance Pharmaceuticals,
                  Inc. Filed as Exhibit 3.4 to our Registration Statement on
                  Form S-1 (File No. 333-35314) and incorporated herein by
                  reference.

      4.3         Form of Common Stock Certificate. Filed as Exhibit 4.1 to our
                  Registration Statement on Form S-1 (File No. 333-35314) and
                  incorporated herein by reference.

      4.4         Form of Common Stock Purchase Warrant, together with a list of
                  holders. Filed as Exhibit 4.2 to our Registration Statement on
                  Form S-1 (File No. 333-35314) and incorporated herein by
                  reference.

      5.1         Opinion of Palmer & Dodge LLP.  Filed herewith.

      23.1        Consent of Arthur Andersen LLP.  Filed herewith.

      23.2        Consent of Palmer & Dodge LLP. Included in the opinion filed
                  as Exhibit 5.1.

      24.1        Power of Attorney.  Included on the signature page hereto.
[{"type": "S-8", "sequence": "1", "filename": "a2033642zs-8.txt", "description": "S-8", "secsgml_size_bytes": 18503}]
{"company-data": {"conformed-name": "GENAISSANCE PHARMACEUTICALS INC", "cik": "0001110009", "assigned-sic": "8731", "irs-number": "061338846", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-52344", "film-number": "792731"}, "business-address": {"street1": "FIVE SCIENCE PARK", "city": "NEW HAVEN", "state": "CT", "zip": "06511", "phone": "2037731450"}, "mail-address": {"street1": "FIVE SCIENCE PARK", "city": "NEW HAVEN", "state": "CT", "zip": "06511"}}
As filed with the Securities and Exchange Commission on December 20, 2000

                                                          REGISTRATION NO. 333-

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D. C. 20549

                                    FORM S-8
                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933

                        GENAISSANCE PHARMACEUTICALS, INC.
             (Exact Name of Registrant as Specified in its Charter)

         DELAWARE                                               06-1338846
      (State or Other                                        (I.R.S. Employer
Jurisdiction of Incorporation)                              Identification No.)

                                FIVE SCIENCE PARK
                          NEW HAVEN, CONNECTICUT 06511
                                 (203) 773-1450
                    (Address of Principal Executive Offices)

                        EMPLOYEE STOCK PURCHASE PLAN 2000
                            (Full Title of the Plan)

                                   KEVIN RAKIN
                      President and Chief Financial Officer
                        Genaissance Pharmaceuticals, Inc.
                                Five Science Park
                          New Haven, Connecticut 06511
                                 (203) 773-1450
            (Name, Address and Telephone Number of Agent for Service)

                                 with copies to:

                              MICHAEL LYTTON, ESQ.
                               Palmer & Dodge LLP
                                One Beacon Street
                           Boston, Massachusetts 02108
                                 (617) 573-0100

                         CALCULATION OF REGISTRATION FEE
----------------------------------------- ------------------ -------------------- -------------------- ----------------
                                                              Proposed maximum     Proposed maximum       Amount of
Title of each class of securities to be     Amount to be     offering price per   aggregate offering    registration
               registered                    registered           share (1)            price (1)             fee
----------------------------------------- ------------------ -------------------- -------------------- ----------------

Common Stock, $0.001 par value            250,000 shares           $21.9375           $5,484,375             $1,448
----------------------------------------- ------------------ -------------------- -------------------- ----------------
(1)  Estimated solely for the purpose of determining the registration fee and
     computed pursuant to Rule 457(h)(1). The proposed maximum offering price
     per share indicated equals the average of the high and low sale price of
     the Common Stock as reported by the Nasdaq National Market on December 15,
     2000.
PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

         The following documents previously filed with the Securities and
Exchange Commission are incorporated by reference herein and shall be deemed as
part hereof:

         (a)      the prospectus contained in our registration statement on
                  Form S-1 (File No. 333-35314) filed under the Securities Act
                  of 1933, as amended, (the "Securities Act") on August 1, 2000;

         (b)      our quarterly reports on Form 10-Q for the quarters ended June
                  30, 2000 and September 30, 2000 filed under the Securities
                  Exchange Act of 1934, as amended, (the "Exchange Act") on
                  September 1, 2000 and November 14, 2000, respectively (File
                  No. 000-30981); and

         (c)      the description of our common stock contained in our
                  Registration Statement on Form 8-A filed on July 11, 2000,
                  including any amendment or report filed hereafter for the
                  purpose of updating such description.

         All documents filed after the date of this registration statement
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act of 1934 and
prior to the filing of a post-effective amendment that indicates that all shares
of common stock offered hereunder have been sold or that deregisters all shares
of common stock remaining unsold shall be deemed to be incorporated by reference
herein and to be a part hereof from the date of the filing of such reports and
documents.

ITEM 4.  DESCRIPTION OF SECURITIES.

         Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

         Not applicable.

ITEM 6.  INDEMNIFICATION OF OFFICERS AND DIRECTORS.

         Section 145 of the Delaware General Corporation Law provides that a
corporation may indemnify any person who was or is a party or is threatened to
be made a party to any threatened, pending or completed action, suit or
proceeding, whether civil, criminal, administrative or investigative, other than
an action by or in the right of the corporation, by reason of the fact that the
person is or was a director, officer, employee or agent of the corporation or is
or was serving at the corporation's request as a director, officer, employee or
agent of another corporation, partnership, joint venture, trust or other
enterprise, against expenses, including attorneys' fees, judgments, fines and
amounts paid in settlement actually and reasonably incurred by the person in
connection with the action, suit or proceeding if the person acted in good faith
and in a manner the person reasonably believed to be in or not opposed to the
best interests of the corporation, and, with respect to any criminal action or
proceeding, had no reasonable cause to believe the person's conduct was
unlawful. The power to indemnify applies to actions brought by or in the right
of the corporation as well, but only to the extent of expenses, including
attorneys' fees but excluding judgments, fines and amounts paid in settlement,
actually and reasonably incurred by the person in connection with the defense or
settlement of the action or suit. In these actions no indemnification shall be
made in the event of any adjudication of negligence or misconduct in the
performance of his duties to the corporation, unless a court believes that in
light of all the circumstances indemnification should apply.

         Article V of Genaissance's Amended and Restated By-laws provides that
Genaissance shall, to the extent legally permitted, indemnify each person who
was or is a party or is threatened to be made a party to any threatened, pending
or completed action, suit or proceeding by reason of the fact that he is or was,
or has agreed to become, a director or officer of Genaissance, or is or was
serving, or has agreed to serve, at the request of Genaissance, as a director,
officer or trustee of, or in a similar capacity with, another corporation,
partnership, joint venture, trust or other enterprises. The indemnification
provided for in Article V is expressly not exclusive of any other rights to

                                       2
which those seeking indemnification may be entitled under any law, agreement or
vote of stockholders or disinterested directors or otherwise, and shall inure to
the benefit of the heirs, executors and administrators of such persons.

         Section 145(g) of the Delaware General Corporation Law and Article V of
Amended and Restated By-laws of Genaissance provide that the company shall have
the power to purchase and maintain insurance on behalf of its officers,
directors, employees and agents, against any liability asserted against and
incurred by such persons in any such capacity.

         Genaissance has entered into indemnification agreements with each of
its directors and has obtained insurance covering its directors and officers
against losses and insuring Genaissance against certain of its obligations to
indemnify its directors and officers.

         Section 102(b)(7) of the General Corporation Law of the State of
Delaware provides that a corporation may eliminate or limit the personal
liability of a director to the corporation or its stockholders for monetary
damages for breach of fiduciary duty as a director, provided that such
provisions shall not eliminate or limit the liability of a director (i) for any
breach of the director's duty of loyalty to the corporation or its stockholders,
(ii) for acts or omissions not in good faith or which involve intentional
misconduct or a knowing violation of law, (iii) under Section 174 of the General
Corporation Law of the State of Delaware, or (iv) for any transaction from which
the director derived an improper personal benefit. No such provision shall
eliminate or limit the liability of a director for any act or omission occurring
prior to the date when such provision becomes effective.

         Pursuant to the Delaware General Corporation Law, Section 6 of Article
FIFTH of the Amended and Restated Certificate of Incorporation of Genaissance
eliminates a director's personal liability for monetary damages to Genaissance
and its stockholders for breach of fiduciary duty as a director, except in
circumstances involving a breach of the director's duty of loyalty to
Genaissance or its stockholders, acts or omissions not in good faith,
intentional misconduct, knowing violations of the law, liability under Section
174 of the Delaware Corporation Law or any transaction from which the director
derived an improper personal benefit.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

         Not applicable.

ITEM 8.  EXHIBITS.

         See Exhibit Index immediately following signature pages.

ITEM 9.  UNDERTAKINGS.

         (a)      The undersigned registrant hereby undertakes:

                  (1)      To file, during any period in which offers or sales
are being made, a post-effective amendment to this registration statement:

                           (i)      To include any prospectus required by
Section 10 (a)(3) of the Securities Act of 1933;

                           (ii)     To reflect in the prospectus any facts or
events arising after the effective date of this registration statement (or the
most recent post-effective amendment thereof) which, individually or in the
aggregate, represents a fundamental change in the information set forth in this
registration statement;

                           (iii)    To include any material information with
respect to the plan of distribution not previously disclosed in this
registration statement or any material change to such information in this
registration statement; provided, however, that paragraphs (a) (1) (i) and (a)
(1) (ii) do not apply if the information required to be included in a
post-effective amendment by those paragraphs is contained in periodic reports
filed by the Registrant pursuant to Section 13 or Section 15(d) of the Exchange
Act of 1934 that are incorporated by reference in this Registration Statement.

                                       3
(2) That, for the purpose of determining any liability under
the Securities Act of 1933, each such post-effective amendment shall be deemed
to be a new registration statement relating to the securities offered therein,
and the offering of such securities at that time shall be deemed to be the
initial bona fide offering thereof.

                  (3) To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

         (b) The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act of 1934 that is incorporated by reference in this registration
statement shall be deemed to be a new registration statement relating to the
securities offered therein and the offering of such securities at that time
shall be deemed to be initial bona fide offering thereof.

         (c) Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the registrant pursuant to the provisions referred to in Item 6
hereof, or otherwise, the registrant has been advised that in the opinion of the
Securities and Exchange Commission such indemnification is against public policy
as expressed in the Securities Act of 1933 and is, therefore, unenforceable. In
the event that a claim for indemnification against such liabilities (other than
the payment by the registrant of expenses incurred or paid by a directors,
officer or controlling person of the registrant in the successful defense of any
action, suit or proceeding) is asserted by such director, officer, or
controlling person in connection with the securities being registered, the
registrant will, unless in the opinion of its counsel the matter has been
settled by controlling precedent, submit to a court of appropriate jurisdiction
the question whether such indemnification by it is against public policy as
expressed in the Securities Act of 1933 and will be governed by the final
jurisdiction of such issue.

                                       4
SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has duly caused this Registration Statement to be
signed on its behalf by the undersigned, thereunto duly authorized, in the Town
of New Haven, Connecticut on December 20, 2000.

                                   GENAISSANCE PHARMACEUTICALS, INC.

                                   By:  /s/ Kevin Rakin
                                        ---------------------------------------
                                        Kevin Rakin
                                        President and Chief Financial Officer

                                POWER OF ATTORNEY

         We, the undersigned officers and directors of Genaissance
Pharmaceuticals, Inc., hereby severally constitute and appoint Gualberto Ruano,
M.D., Ph.D., Kevin Rakin and Michael Lytton and each of them singly, our true
and lawful attorneys-in-fact, with full power to them in any and all capacities,
to sign any amendments to this Registration Statement on Form S-8 (including any
post-effective amendments thereto), and to file the same, with exhibits thereto
and other documents in connection therewith, with the Securities and Exchange
Commission, hereby ratifying and confirming all that each of said
attorneys-in-fact may do or cause to be done by virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities and on the dates indicated.
SIGNATURE                                     TITLE                                            DATE
/S/ GUALBERTO RUANO                           Chief Executive Officer and Director             December 20, 2000
------------------------------------          (Principal Executive Officer)
Gualberto Ruano, M.D., Ph.D.

/S/ KEVIN RAKIN                               Chief Financial Officer (Principal Financial     December 20, 2000
------------------------------------          and Accounting Officer) and Director
Kevin Rakin

/S/ JURGEN DREWS                              Chairman of the Board                            December 20, 2000
------------------------------------
Jurgen Drews, M.D.

/S/ GERHARD LAUR                              Director                                         December 20, 2000
------------------------------------
Gerhard Laur, M.D.

/S/ HARRY H. PENNER, JR.                      Director                                         December 20, 2000
------------------------------------
Harry H. Penner, Jr., J.D.

SETH RUDNICK                                  Director                                         December 20, 2000
------------------------------------
Seth Rudnick, M.D.

STEFAN RYSER                                  Director                                         December 20, 2000
------------------------------------
Stefan Ryser, Ph.D.

CHRISTOPHER WRIGHT                            Director                                         December 20, 2000
------------------------------------
Christopher Wright
5
EXHIBIT INDEX

    EXHIBIT
     NUMBER               DESCRIPTION

      4.1         Amended and Restated Certificate of Incorporation of
                  Genaissance Pharmaceuticals, Inc. Filed as Exhibit 3.2 to our
                  Registration Statement on Form S-1 (File No. 333-35314) and
                  incorporated herein by reference.

      4.2         Amended and Restated By-laws of Genaissance Pharmaceuticals,
                  Inc. Filed as Exhibit 3.4 to our Registration Statement on
                  Form S-1 (File No. 333-35314) and incorporated herein by
                  reference.

      4.3         Form of Common Stock Certificate. Filed as Exhibit 4.1 to our
                  Registration Statement on Form S-1 (File No. 333-35314) and
                  incorporated herein by reference.

      4.4         Form of Common Stock Purchase Warrant, together with a list of
                  holders. Filed as Exhibit 4.2 to our Registration Statement on
                  Form S-1 (File No. 333-35314) and incorporated herein by
                  reference.

      5.1         Opinion of Palmer & Dodge LLP.  Filed herewith.

      23.1        Consent of Arthur Andersen LLP.  Filed herewith.

      23.2        Consent of Palmer & Dodge LLP. Included in the opinion filed
                  as Exhibit 5.1.

      24.1        Power of Attorney.  Included on the signature page hereto.