As filed with the Securities and Exchange Commission on April 9, 1997

                                          Registration No. 333-
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                   ----------

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

                                   ----------

                           ALEXION PHARMACEUTICALS, INC.
               ------------------------------------------------------
               (Exact name of registrant as specified in its charter)

     DELAWARE                                               13-3648318
     (State or other jurisdiction                           (I.R.S. Employer
     of incorporation or                                    Identification
     organization)                                          Number)
                                      
                                  25 SCIENCE PARK
                            NEW HAVEN, CONNECTICUT 06511
                                   (203) 776-1790
               (Address, including zip code, and telephone number,
        including area code, of registrant's principal executive offices)


                           ALEXION PHARMACEUTICALS, INC.
                               1992 STOCK OPTION PLAN
                              (full title of the plan)

                                   ----------

                                 LEONARD BELL, M.D.
                          ALEXION PHARMACEUTICALS, INC.
                                  25 SCIENCE PARK
                            NEW HAVEN, CONNECTICUT 06511
                                   (203) 776-1790
            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)

                                   ----------

     Copies of all communications, including all communications sent to the
                     agent for service, should be sent to:

                              MERRILL M. KRAINES, ESQ.
                            FULBRIGHT & JAWORSKI L.L.P.
                                  666 FIFTH AVENUE
                              NEW YORK, NEW YORK 10103
                                   (212) 318-3000

                                   ----------
CALCULATION OF REGISTRATION FEE =============================================================================================== PROPOSED MAXIMUM PROPOSED MAXIMUM AMOUNT OF TITLE OF SECURITIES AMOUNT TO BE OFFERING PRICE AGGREGATE OFFERING REGISTRATION TO BE REGISTERED REGISTERED PER UNIT(1) PRICE (1) FEE =============================================================================================== COMMON STOCK $.0001 PAR VALUE PER SHARE 1,800,000 SHARES $10.00 $18,000,000 $5,455.00 ===============================================================================================
(1) THE PRICE IS ESTIMATED IN ACCORDANCE WITH RULE 457(h)(1) UNDER THE SECURITIES ACT OF 1933, AS AMENDED, SOLELY FOR THE PURPOSE OF CALCULATING THE REGISTRATION FEE, BASED ON THE AVERAGE OF THE HIGH AND LOW PRICES OF THE COMMON STOCK AS REPORTED ON THE NASDAQ NATIONAL MARKET ON APRIL 4, 1997. ================================================================================ PART I INFORMATION REQUIRED IN THE PROSPECTUS The document(s) containing the information called for in Part I of Form S-8 will be sent or given to individuals awarded options under the Alexion Pharmaceuticals, Inc. 1992 Stock Option Plan adopted by Alexion Pharmaceuticals, Inc. and is not being filed with or included in this Form S-8 in accordance with the rules and regulations of the Securities and Exchange Commission. PART II INFORMATION REQUIRED IN THE REGISTRATION STATEMENT ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE The following documents filed by Alexion Pharmaceuticals, Inc. (the "Company") are incorporated herein by reference: (a) The Company's Annual Report on Form 10-K for the fiscal year ended July 31, 1996, filed on October 29, 1996, as amended by Form 10-K/A, filed April 9, 1997. (b) The Company's Quarterly Report on Form 10-Q for the fiscal quarter ended October 31, 1996, filed on December 12, 1996. (c) The Company's Quarterly Report on Form 10-Q for the fiscal quarter ended January 31, 1997, filed on March 17, 1997, as amended by Form 10-Q/A, filed March 17, 1997. (d) The description of the Company's Common Stock contained in Item 1 of the Company's Registration Statement on Form 8-A dated February 12, 1996. In addition to the foregoing, all documents subsequently filed by the Company pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934, prior to the filing of a post-effective amendment indicating that all of the securities offered hereunder have been sold or deregistering all securities then remaining unsold, shall be deemed to be incorporated by reference in this Registration Statement and to be part hereof from the date of filing of such documents. Any statement contained in a document incorporated by reference in this Registration Statement shall be deemed to be modified or superseded for purposes of this Registration Statement to the extent that a statement contained herein or in any subsequently filed document that is also incorporated by reference herein modifies or supersedes such statement. Any statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this Registration Statement. ITEM 4. DESCRIPTION OF SECURITIES Not applicable. ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL Not applicable. II-1 ITEM 6. INDEMNIFICATION OF DIRECTORS AND OFFICERS Section 145 of the General Corporation Law of the State of Delaware permits indemnification of directors, officers and employees of a corporation under certain conditions and subject to certain limitations. The Certificate of Incorporation of the Company provides that the Company shall, to the fullest extent permitted by Section 145, indemnify any and all persons whom it shall have power to indemnify under said Section. In addition, the Company has entered into Indemnity Agreements with its directors and officers providing for the maximum indemnification allowed by Section 145. ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED Not Applicable. ITEM 8. EXHIBITS 4(a) Alexion Pharmaceuticals, Inc. 1992 Stock Option Plan. (b) Form of Incentive Option Agreement. (c) Form of Nonqualified Option Agreement. 5 Opinion of Fulbright & Jaworski L.L.P. 23(a) Consent of Arthur Andersen LLP (b) Consent of Fulbright & Jaworski L.L.P. (included in Exhibit 5). 24 Power of Attorney (included in signature page). II-2 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 dates of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement; (iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement; (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 Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan's annual report pursuant to Section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the 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 the initial bona fide offering thereof. II-3 (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 foregoing provisions, 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 a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, 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 of the registrant 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 adjudication of such issue. II-4 SIGNATURES Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of New Haven, State of Connecticut on April 4, 1997. ALEXION PHARMACEUTICALS, INC. By: /s/ LEONARD BELL, M.D. ------------------------------------- Leonard Bell, M.D. President, Chief Executive Officer, Secretary and Treasurer POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that each individual whose signature appears below constitutes and appoints LEONARD BELL, M.D. and DAVID W. KEISER, or either of them, his true and lawful attorney-in-fact and agent with full power of substitution and resubstitution, for him and in his name, place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement, and to file the same with all exhibits thereto, and all documents in connection therewith, with the Securities and Exchange Commission, granting said attorney-in-fact and agent, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorney-in-fact and agent or any of them, or their or his substitute or substitutes, may lawfully do or cause to be done by virtue hereof. Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated: /s/ LEONARD BELL, M.D. President, Chief Executive Officer, - -------------------------------- Secretary, Treasurer and Director April 4, 1997 Leonard Bell, M.D. (principal executive officer) /s/ DAVID W. KEISER Executive Vice President and Chief - -------------------------------- Operating Officer (principal financial April 4, 1997 David W. Keiser officer) /s/ BARRY P. LUKE Senior Director of Finance and April 4, 1997 - -------------------------------- Administration (principal accounting officer) Barry P. Luke /s/ JOHN H. FRIED, PH.D. - -------------------------------- Chairman of the Board of Directors April 4, 1997 John H. Fried, Ph.D. /s/ JOSEPH A. MADRI, PH.D., M.D. - -------------------------------- Director April 4, 1997 Joseph A. Madri, Ph.D., M.D. /s/ LEONARD MARKS, JR., PH.D. - -------------------------------- Director April 4, 1997 Leonard Marks, Jr., Ph.D. /s/ MAX LINK, PH.D. - -------------------------------- Director April 4, 1997 Max Link, Ph.D. /s/ EILEEN M. MORE - -------------------------------- Director April 4, 1997 Eileen M. More /s/ TIMOTHY F. HOWE - -------------------------------- Director April 4, 1997 Timothy F. Howe
II-5

                                                                    EXHIBIT 4(a)

                        ALEXION PHARMACEUTICALS, INC.
                             1992 STOCK OPTION PLAN

     1. Purpose. The purpose of the Alexion Pharmaceuticals, Inc. 1992 Stock
Option Plan (the "Plan") is to enable Alexion Pharmaceuticals, Inc. (the
"Company") and its stockholders to secure the benefits of common stock ownership
by key personnel of the Company and its subsidiaries. The Board of Directors of
the Company (the "Board") believes that the granting of options under the Plan
will foster the Company's ability to attract, retain and motivate those
individuals who will be largely responsible for the profitability and long-term
future growth of the Company.

     2. Stock Subject to the Plan. The Company may issue and sell a total of
1,800,000 shares of its common stock, $.0001 par value (the "Common Stock"),
pursuant to the Plan. Such shares may be either authorized and unissued or held
by the Company in its treasury. New options may be granted under the Plan with
respect to shares of Common Stock which are covered by the unexercised portion
of an option which has terminated or expired by its terms, by cancellation or
otherwise.

     3. Administration. The Plan will be administered by a committee (the
"Committee") consisting of at least two directors appointed by and serving at
the pleasure of the Board. Unless the Board determines otherwise, the members of
the Committee are to be "disinterested directors" within the meaning and for the
purposes of Rule 16(b)-3 under the Securities Exchange Act of 1934. Subject to
the provisions of the Plan, the Committee, acting in its sole and absolute
discretion, will have full power and authority to grant options under the Plan,
to interpret the provisions of the Plan, to fix and interpret the provisions of
option agreements made under the Plan, to supervise the administration of the
Plan, and to take such other action as may be necessary or desirable in order to
carry out the provisions of the Plan. A majority of the members of the Committee
will constitute a quorum. The Committee may act by the vote of a majority of its
members present at a meeting at which there is a quorum or by unanimous written
consent. The decision of the Committee as to any disputed question, including
questions of construction, interpretation and administration, will be final and
conclusive on all persons. The Committee will keep a record of its proceedings
and acts and will keep or cause to be kept such books and records as may be
necessary in connection with the proper administration of the Plan.

     4. Eligibility. Options may be granted under the Plan to present or future
key employees of the Company or a subsidiary of the Company (a "Subsidiary")
within the meaning of Section 424(f) of the Internal Revenue Code of 1986 (the
"Code"), and to consultants to the Company or a Subsidiary who are not
employees. Options may be granted to directors of the Company or a Subsidiary
whether or not also employees of or consultants to the Company and/or a
Subsidiary. Subject to the provisions of the Plan, the Committee may from time
to time select the persons to whom options will be granted, and will fix the
number of shares covered by each such option and establish the terms and
conditions thereof (including, without limitation, exercise price and
restrictions on exercisability of the option or on the shares of Common Stock
issued upon exercise thereof and whether or not the option is to be 





treated as an incentive stock option within the meaning of Section 422 of the
Code (an "Incentive Stock Option").

     5. Terms and Conditions of Options. Each option granted under the Plan will
be evidenced by a written agreement in a form approved by the Committee. Each
such option will be subject to the terms and conditions set forth in this
paragraph and such additional terms and conditions not inconsistent with the
Plan (and, in the case of an Incentive Stock Option, not inconsistent with the
provisions of the Code applicable thereto) as the Committee deems appropriate.

          (a) Option Exercise Price. In the case of an option which is not
treated as an Incentive Stock Option, the exercise price per share may not be
less than the par value of a share of Common Stock on the date the option is
granted; and, in the case of an Incentive Stock Option, the exercise price per
share may not be less than 100% of the fair market value of a share of Common
Stock on the date the option is granted (110% in the case of an optionee who, at
the time the option is granted, owns stock possessing more than 10% of the total
combined voting power of all classes of stock of the Company or a Subsidiary (a
"ten percent shareholder")). For purposes hereof, the fair market value of a
share of Common Stock on any date will be equal to the closing sale price per
share as published by a national securities exchange on which shares of the
Common Stock are traded on such date or, if there is no sale of Common Stock on
such date, the average of the bid and asked prices on such exchange at the
closing of trading on such date or, if shares of the Common Stock are not listed
on a national securities exchange on such date, the closing price or, if none,
the average of the bid and asked prices in the over the counter market at the
close of trading on such date, or if the Common Stock is not traded on a
national securities exchange or the over the counter market, the fair market
value of a share of the Common Stock on such date as determined in good faith by
the Committee.

          (b) Option Period. The period during which an option may be exercised
will be fixed by the Committee and will not exceed 10 years from the date the
option is granted (5 years in the case of an Incentive Stock Option granted to a
"ten percent shareholder").

          (c) Exercise of Options. Unless otherwise determined by the Committee,
no option will become exercisable unless the person to whom the option was
granted remains in the continuous employ or service of the Company or a
Subsidiary for at least one year (or for such other period as the Committee may
designate) from the date the option is granted. Subject to earlier termination
of the option as provided herein, unless the Committee determines otherwise, the
option will become exercisable in accordance with the following schedule based
upon the number of full years of the optionee's continuous employment or service
with the Company or a Subsidiary following the date of grant:





          Full                   Incremental         Cumulative
          Years of Continuous    Percentage of       Percentage of
          Employment/            Option              Option
          Service                Exercisable         Exercisable
          --------------------   -------------       -------------
          Less than 1                  0%                  0%
                    1                 20%                 20%
                    2                 20%                 40%
                    3                 20%                 60%
                    4                 20%                 80%
                    5 or more         20%                100%


All or part of the exercisable portion of an option may be exercised at any time
during the option period, except that, without the consent of the Committee, no
partial exercise of an option may be for less than 100 shares. An option may be
exercised by transmitting to the Company (1) a written notice specifying the
number of shares to be purchased, and (2) payment of the exercise price (or, if
applicable, delivery of a secured obligation therefor), together with the
amount, if any, deemed necessary by the Committee to enable the Company to
satisfy its income tax withholding obligations with respect to such exercise
(unless other arrangements acceptable to the Company are made with respect to
the satisfaction of such withholding obligations).

          (d) Payment of Exercise Price. The purchase price of shares of Common
Stock acquired pursuant to the exercise of an option granted under the Plan may
be paid in cash and/or such other form of payment as may be permitted under the
option agreement, including, without limitation, previously-owned shares of
Common Stock. The Committee may permit the payment of all or a portion of the
purchase price in installments (together with interest) over a period of not
more than 5 years.

          (e) Rights as a Stockholder. No shares of Common Stock will be issued
in respect of the exercise of an option granted under the Plan until full
payment therefor has been made (and/or provided for where all or a portion of
the purchase price is being paid in installments). The holder of an option will
have no rights as a stockholder with respect to any shares covered by an option
until the date a stock certificate for such shares is issued to him or her.
Except as otherwise provided herein, no adjustments shall be made for dividends
or distributions of other rights for which the record date is prior to the date
such stock certificate is issued.

          (f) Nontransferability of Options. No option shall be assignable or
transferrable except upon the optionee's death to a beneficiary designated by
the optionee in accordance with procedures established by the Committee or, if
no designated beneficiary shall survive the optionee, pursuant to the optionee's
will or by the laws of descent and distribution. During an optionee's lifetime,
options may be exercised only by the optionee or the optionee's guardian or
legal representative.





                  (g) Termination of Employment or Other Service. If an optionee
ceases to be employed by or to perform services for the Company and any
Subsidiary for any reason other than death or disability (defined below), then,
unless the Committee determines otherwise, each outstanding option granted to
him or her under the Plan will terminate on the date three months after the date
of such termination of employment or service. If an optionee's employment or
service is terminated by reason of the optionee's death or disability (or if the
optionee's employment or service is terminated by reason of his or her
disability and the optionee dies within one year after such termination of
employment or service), then each outstanding option granted to the optionee
under the Plan will terminate on the date one year after the date of such
termination of employment or service (or one year after the later death of a
disabled optionee) or, if earlier, the date specified in the option agreement.
For purposes hereof, the term "disability" means the inability of an optionee to
perform the customary duties of his or her employment or other service for the
Company or a Subsidiary by reason of a physical or mental incapacity which is
expected to result in death or be of indefinite duration.

          (h) Maximum Option Grant. The maximum option grant which may be made
to an employee of the Company in any calendar year shall not cover more than
200,000 shares.

          (i) Other Provisions. The Committee may impose such other conditions
with respect to the exercise of options, including, without limitation, any
conditions relating to the application of federal or state securities laws, as
it may deem necessary or advisable.

     6. Capital Changes, Reorganization, Sale.

          (a) Adjustments Upon Changes in Capitalization. The aggregate number
and class of shares for which options may be granted under the Plan, the number
and class of shares covered by each outstanding option and the exercise price
per share shall all be adjusted proportionately for any increase or decrease in
the number of issued shares of Common Stock resulting from a split-up or
consolidation of shares or any like capital adjustment, or the payment of any
stock dividend.

          (b) Cash, Stock or Other Property for Stock. Except as otherwise
provided in this subparagraph, in the event of an Exchange Transaction (as
defined below), all optionees will be permitted to exercise their outstanding
options (whether or not otherwise exercisable) and any outstanding options not
exercised before the consummation of the Exchange Transaction will thereupon
terminate. Notwithstanding the preceding sentence, if, as part of the Exchange
Transaction, the shareholders of the Company receive capital stock of another
corporation ("Exchange Stock), and if the Board, in its sole discretion, so
directs, then all outstanding options will be converted into options to purchase
shares of Exchange Stock. The amount and price of the converted options will be
determined by adjusting the amount and price of the options granted hereunder on
the same basis as the determination of the number of shares of Exchange Stock
the holders of Common Stock will receive in the Exchange Transaction.





          (c) Definition of Exchange Transaction. For purposes hereof, the term
"Exchange Transaction" means a merger (other than a merger of the Company in
which the holders of Common Stock immediately prior to the merger have the same
proportionate ownership of Common Stock in the surviving corporation immediately
after the merger), consolidation, acquisition of property or stock, separation,
reorganization (other than a mere reincorporation or the creation of a holding
company) or liquidation of the Company, as a result of which the Shareholders of
the Company receive cash, stock or other property in exchange for or in
connection with their shares of Common Stock.

          (d) Fractional Shares. In the event of any adjustment in the number of
shares covered by any option pursuant to the provisions hereof, any fractional
shares resulting from such adjustment will be disregarded and each such option
will cover only the number of full shares resulting from the adjustment.

          (e) Determination of Board to be Final. All adjustments under this
paragraph 6 shall be made by the Board, and its determination as to what
adjustments shall be made, and the extent thereof, shall be final, binding and
conclusive. Unless an optionee agrees otherwise, any change or adjustment to an
Incentive Stock Option shall be made in such a manner so as not to constitute a
"modification" as defined in Section 424(h) of the Code and so as not to cause
the optionee's Incentive Stock Option issued hereunder to fail to continue to
qualify as an Incentive Stock Option.

     7. Amendment and Termination of the Plan. The Board may amend or terminate
the Plan. Except as otherwise provided in the Plan with respect to equity
changes, any amendment which would increase the aggregate number of shares of
Common Stock as to which options may be granted under the Plan, materially
increase the benefits under the Plan, or modify the class of persons eligible to
receive options under the Plan shall be subject to the approval of the holders
of a majority of the Common Stock issued and outstanding. No amendment or
termination may affect adversely any outstanding option without the written
consent of the optionee.

     8. No Rights Conferred. Nothing contained herein will be deemed to give any
individual any right to receive an option under the Plan or to be retained in
the employ or service of the Company or any Subsidiary.

     9. Governing Law. The Plan and each option agreement shall be governed by
the laws of the State of Delaware.

     10. Decisions and Determinations of Committee to be Final. Except to the
extent rights or powers under this Plan are reserved specifically to the
discretion of the Board, all decisions and determinations of the Committee are
final and binding.

     11. Term of the Plan. The Plan shall be effective as of February 27, 1992,
the date on which it was adopted by the Board, subject to the approval of the
stockholders of the Company, which approval was granted on February 27, 1992.
The Plan will 





terminate on February 26, 2002, the date ten years after the date of adoption by
the Board, unless sooner terminated by the Board. The rights of optionees under
the options outstanding at the time of the termination of the Plan shall not be
affected solely by reason of the termination and shall continue in accordance
with the terms of the option (as then in effect or thereafter amended).



                                                                    EXHIBIT 4(b)

                          ALEXION PHARMACEUTICALS, INC.

                        INCENTIVE STOCK OPTION AGREEMENT

     AGREEMENT made as of the ___ day of _________, 199__, by and between
Alexion Pharmaceuticals, Inc., a Delaware corporation (the "Company") and
_____________________ (the "Optionee").

                               W I T N E S S E T H

     WHEREAS, pursuant to the Alexion Pharmaceuticals, Inc. 1992 Stock Option
Plan (the "Plan"), the Company desires to grant to the Optionee and the Optionee
desires to accept an option to purchase shares of common stock, $.0001 par
value, of the Company (the "Common Stock") upon the terms and conditions set
forth in this agreement:

     NOW, THEREFORE, the parties hereto agree as follows:

          1. Grant. The Company hereby grants this day (the Grant Date) to the
Optionee an option to purchase _____________ shares of Common Stock, at a
purchase price of $___________ per share. This option is intended to be treated
as an option which is an incentive stock option within the meaning of Section
422 of the Internal Revenue Code of 1986.

          2. Restrictions on Exercisability. Except as specifically provided
otherwise herein, the option will become exercisable in accordance with the
following schedule based upon the number of full years of the Optionee's
continuous employment or service with the Company or a subsidiary following the
Grant Date:

      Full Years of              Incremental             Cumulative
      Continuous                 Percentage of           Percentage of
      Employment/                Option                  Option
      Service                    Exercisable             Exercisable
      -------------              -------------           --------------
      Less than   1                   0%                      0%
                  1                  25%                     25%
                  2                  25%                     50%
                  3                  25%                     75%
                  4 or more          25%                    100%
         
No shares of Common Stock may be purchased hereunder unless the Optionee shall
have remained in the continuous employ or service of the Company or a subsidiary
for one year from the Grant Date. If the Optionee performs services for the
Company or a subsidiary in a capacity other than as a director or employee,
then, for purposes 





hereof, those services will be deemed to be continuous until they are
terminated, and they will be deemed to be terminated at the time provided
therefor in the consulting or other agreement governing the performance of such
services or, if there is no such agreement, at the time the Company notifies the
Optionee that it no longer contemplates the utilization of such services. Unless
sooner terminated, the option will expire if and to the extent it is not
exercised within ten years from the Grant Date.

          3. Exercise. The option may be exercised in whole or in part in
accordance with the above schedule by delivering to the Secretary of the Company
(a) a written notice specifying the number of shares to be purchased, and
(b) payment in full of the exercise price, together with the amount, if any,
deemed necessary by the Company to enable it to satisfy any income tax
withholding obligations with respect to the exercise (unless other arrangements,
acceptable to the Company, are made for the satisfaction of such withholding
obligation). The exercise price shall be payable by bank or certified check. The
Company may (in its sole and absolute discretion) permit all or part of the
exercise price to be paid with previously-owned shares of Common Stock, or in
installments (together with interest) evidenced by the Optionee's secured
promissory note.

          4. Rights as Stockholder. No shares of Common Stock shall be sold or
delivered hereunder until full payment for such shares has been made (or, to the
extent payable in installments, provided for). The Optionee shall have no rights
as a stockholder with respect to any shares covered by the option until a stock
certificate for such shares is issued to him or her. Except as otherwise
provided herein, no adjustment shall be made for dividends of distributions of
other rights form which the record is prior to the date such stock certificate
is issued.

          5. Nontransferability. The option is not assignable or transferable
except upon the Optionee's death to a beneficiary designated by the Optionee or,
if no designated beneficiary shall survive the Optionee, pursuant to the
Optionee's will and/or the laws of descent and distribution. During an
Optionee's lifetime, the option may be exercised only by the Optionee or the
Optionee's guardian or legal representative.

          6. Termination of Service, Disability or Death. If the Optionee ceases
to be employed by or to perform services for the Company and any subsidiary for
any reason other than death or disability, then, unless sooner terminated under
the terms hereof, the option will terminate on the date three months after the
date of the Optionee's termination of employment or service. If the Optionee's
employment or service is terminated by reason of the Optionee's death or
disability (or if the Optionee's employment or services is terminated by reason
of his or her disability and the Optionee dies within one year after such
termination of employment or service), then, unless sooner terminated under the
terms hereof, the option will terminate on the date one year after the date of
such termination of employment or service (or one year after the Optionee's
later death).

          7. Securities Restrictions. If the shares to be issued upon an
exercise of the option are not registered under the Securities Act of 1933,
then, as a further 




condition of the Company's obligation to issue such shares, the Optionee may be
required to give a representation in writing that the Optionee is acquiring the
shares for his or her own account as an investment and not with a view to, or
for the sale in connection with, the distribution of such shares, and the
certificates representing such shares shall bear a legend to such effect as the
Company's counsel shall deem necessary or desirable. The option shall in no
event be exercisable and shares shall not be issued hereunder if, in the option
of counsel to the Company, such exercise and/or issuance would result in a
violation of federal or state securities laws.

          8. Capital changes, Reorganizations, Etc.

               a. In case of any post-Grant Date split-up or consolidation of
shares or any like capital adjustment, or the payment of stock dividend which
increases or decreases the number of outstanding shares of Common Stock,
appropriate adjustment shall be made to the number of shares and the exercise
price per share which may still be purchased under this agreement.

               b. Upon a post-Grant Date merger (other than a merger of the
Company in which the holders of Common Stock immediately prior to the merger
have the same proportionate ownership of common stock in the surviving
corporation immediately after the merger), consolidation, sale of property or
stock, separation, reorganization (other than a mere reincorporation or the
creation of a holding company) or liquidation of the Company, as a result of
which the stockholders of the company receive cash, stock or other property in
exchange for or in connection with their shares of Common Stock (an "Exchange
Transaction"), the Optionee will be permitted to exercise his or her outstanding
options (whether or not otherwise exercisable) and any outstanding options not
exercised before the consummation of the Exchange Transaction will thereupon
terminate. Notwithstanding the preceding sentence, if, as part of the Exchange
Transaction, the shareholders of the Company receive capital stock of another
corporation ("Exchange Stock"), and if the Board, in its sole discretion, so
directs, then all outstanding options will be converted into options to purchase
shares of Exchange Stock. The Amount and price of the converted options will be
determined by adjusting the amount and price of the options granted hereunder on
the same basis as the determination of the number of shares of Exchange Stock
the holders of Common Stock will receive in the Exchange Transaction.

               c. In the event of any adjustment in the number of shares covered
by any option pursuant to the provisions hereof, any fractional shares resulting
from such adjustment will be disregarded and each such option will cover only
the number of full shares resulting from the adjustment.

               d. All adjustments under this paragraph 8 shall be made by the
Board, and its determination as to what adjustments shall be made, and the
extent thereof, shall be final, binding and conclusive. Unless the Optionee
agrees otherwise, any change or adjustment to the option shall be made in such a
manner so as not to constitute a "modification" as defined in Section 424(h) of
the Code and so as not to cause the Optionee's option to fail to continue to
qualify as an Incentive Stock Option.





          9. No Employment Rights. Nothing in this agreement shall give the
Optionee any right to continue in the employ or service of the Company or a
subsidiary, or interfere in any way with the right of the Company to terminate
the employment or the service of the Optionee.

          10. Provisions of the Plan. The provisions of the Plan shall govern if
and to the extent that there are inconsistencies between those provisions and
the provisions hereof. The Optionee acknowledges that he or she received a copy
of the Plan prior to the execution of this Agreement.

          11. Administration. The committee appointed by the Board to administer
the Plan will have full power and authority to interpret and apply the
provisions of this agreement, and the decision of said committee as to any
matter arising under this agreement shall be binding and conclusive as to all
persons.

          12. Miscellaneous.

               a. This agreement shall be binding upon and shall inure to the
benefit of the parties hereto and their respective successors and permitted
assigns.

               b. This agreement shall be governed by and construed in
accordance with the laws of the State of Delaware. This agreement constitutes
the entire agreement between the parties with respect to the subject matter
hereof and may not be modified except by written instrument executed by the
parties.

          IN WITNESS WHEREOF, this agreement has been executed as of the date
first above written.

                                       Alexion Pharmaceuticals, Inc.

                                       By:_________________________________

                                       ____________________________________
                                       Optionee


                                                                    EXHIBIT 4(c)

                          ALEXION PHARMACEUTICALS, INC.

                             STOCK OPTION AGREEMENT

          AGREEMENT made as of the _________________ day of _________ 199_ by
and between Alexion Pharmaceuticals, Inc., a Delaware corporation (the
"Company") and ____________________ (the "Optionee").

                               W I T N E S S E T H

          WHEREAS, pursuant to the Alexion Pharmaceuticals, Inc. 1992 Stock
Option Plan (the "Plan"), the Company desires to grant to the Optionee and the
Optionee desires to accept an option to purchase shares of common stock, $.0001
par value, of the Company (the "Common Stock") upon the terms and conditions set
forth in this agreement;

          NOW, THEREFORE, the parties hereto agree as follows:

          1. Grant. The Company hereby grants to the Optionee an option to
purchase ____________ shares of Common Stock, at a purchase price per share of
$___________. This option is intended to be treated as an option which does not
qualify a an incentive stock option ("NSO") within the meaning of Section 422 of
the Internal Revenue Code of 1986.

          2. Exercisability. This option is immediately exercisable on the date
hereof.

          3. Exercise. The option may be exercised in whole or in part in
accordance with the above schedule by delivering to the Secretary of the Company
(a) a written notice specifying the number of shares to be purchased, and
(b) payment in full of the exercise price, together with the amount, if any,
deemed necessary by the Company to enable it to satisfy any income tax
withholding obligations with respect to the exercise (unless other arrangements,
acceptable to the Company, are made for the satisfaction of such withholding
obligations). The exercise price shall be payable by bank or certified check.
The Company may (in its sole and absolute discretion) permit all or part of the
exercise price to be paid with previously-owned shares of Common Stock, or in
installments (together with interest) evidenced by the Optionee's secured
promissory note.

          4. Rights as Stockholder. No shares of Common Stock shall be sold or
delivered hereunder until full payment for such shares has been made (or, to the
extent payable in installments, provided for). The Optionee shall have no rights
as a stockholder with respect to any shares covered by the option until a stock
certificate for such shares is issued to him or her. Except as otherwise
provided herein, no adjustment shall be made for dividends or distributions of
other rights for which the record date is prior to the date such stock
certificate is issued.




          5. Nontransferability. The option is not assignable or transferable
except upon the Optionee's death to a beneficiary designated by the Optionee or,
if no designated beneficiary shall survive the Optionee, pursuant to the
Optionee's will and/or the laws of descent and distribution. During an
Optionee's lifetime, the option may be exercised only by the Optionee or the
Optionee's guardian or legal representative.

          6. Termination of Service, Disability or Death. If the Optionee ceases
to be employed by or to perform services for the Company and any subsidiary for
any reason other than death or disability, then, unless sooner terminated under
the terms hereof, the option will terminate on the date three months after the
date of the Optionee's termination or employment or service. If the Optionee's
employment or serviced is terminated by reason of the Optionee's death or
disability (or if the Optionee's employment or service is terminated by reason
of his or her disability and the Optionee dies within one year after such
termination or employment or service), then, unless sooner terminated under the
terms hereof, the option will terminate on the date one year after the date of
such termination of employment or service (or one year after the Optionee's
later death).

          7. Securities Restrictions. If the shares to be issued upon an
exercise of the option are not registered under the Securities Act of 1933,
then, as a further condition of the Company's obligation to issue such shares,
the Optionee may be require to give a representation in writing that the
Optionee is acquiring the shares for his or her own account as an investment and
with a view to, or for sale in connection with, the distribution of such shares,
and the certificates representing such shares shall bear a legend to such effect
as the company's counsel shall deem necessary or desirable.

          8. Capital Changes, Reorganization, Etc.

               (a) In case of any post-Grant Date split-up or consolidation of
shares or any like capital adjustment, or the payment of a stock dividend which
increases or decreases the number of outstanding shares of Common Stock,
appropriate adjustment shall be made to the number of shares and the exercise
price per share which may still be purchased under this agreement.

               (b) Upon a post-Grant Date merger (other than a merger of the
Company in which the holders of Common Stock immediately prior to the merger
have the same proportionate ownership of common stock in the surviving
corporation immediately after the merger), consolidation, sale of property or
stock, separation, reorganization (other than a mere reincorporation or the
creation of a holding company) or liquidation of the Company, as a result of
which the stockholders of the Company receive cash, stock or other property in
exchange for or in connection with their shares of Common Stock an ("Exchange
Transaction"), the Optionee will be permitted to exercise his or her outstanding
option (whether or not otherwise exercisable) and any outstanding options not
exercised before the consummation of the Exchange Transaction will thereupon
terminate. Notwithstanding the preceding sentence, if, as part of the Exchange
Transaction, the shareholders of the Company 





receive capital stock of another corporation ("Exchange Stock"), and if the
Board, in its sole discretion, so directs, then all outstanding options will be
converted into options to purchase shares of Exchange Stock. The amount and
price of the converted options will be determined by adjusting the amount and
price of the options granted hereunder on the same basis as the determination of
the number of shares of Exchange Stock and holders of Common Stock will receive
in the Exchange Transaction.

               (c) In the event of any adjustment in the number of shares
covered by any option pursuant to the provisions hereof, any fractional shares
resulting from such adjustment will be disregarded and each such option will
cover only the number of full shares resulting from the adjustment.

               (d) All adjustments under this paragraph 8 shall be made by the
Board, and its determination as to what adjustments shall be made, and the
extent thereof, shall be final, binding and conclusive.

             9. No Employment Rights Nothing in this agreement shall give the
Optionee any right to continue in the employ or service of the Company or a
subsidiary, or interfere in any way with the right of the Company to terminate
the employment or service of the Optionee.

          10. Provisions of Plan. The provisions of the Plan shall govern if an
to the extent that there are inconsistencies between those provisions and the
provisions hereof. The Optionee acknowledges that he or she has received a copy
of the Plan prior to the execution of this agreement.

          11. Administration. The committee appointed by the Board to administer
the Plan or the Board, will have full power and authority to interpret and apply
the provisions of this agreement, and the decision of said committee as to any
matter arising under this agreement shall be binding and conclusive as to all
persons.

          12. Termination of Grant. Prior to the Grant Date, the Board of
Directors if, and to the extent necessary, in order to successfully consummate
the Company's private placement, may not grant the option, and to that extent,
the Optionee will have no further rights hereunder.

          13. Miscellaneous.

               (a) This agreement shall be binding upon and shall inure to the
benefit of the parties hereto and their respective successors and permitted
assigns.

               (b) This agreement shall be governed by and construed in
accordance with the laws of the State of Delaware. This agreement constitutes
the entire agreement between the parties with respect to the subject matter
hereof and may not be modified except by written instrument executed by the
parties.

          IN WITNESS WHEREOF, this agreement has been executed as of the date
first above written.





                                       Alexion Pharmaceuticals, Inc.

                                       By:_____________________________

                                       ________________________________
                                       Optionee

                                                                       EXHIBIT 5


                              FULBRIGHT & JAWORSKI              HOUSTON         
                                     L.L.P.                     WASHINGTON, D.C.
                   A Registered Limited Liability Partnership   AUSTIN          
                                666 Fifth Avenue                SAN ANTONIO     
                            New York, New York 10103            DALLAS          
                                                                NEW YORK        
telephone: 212/318-3000                                         LOS ANGELES     
facsimile: 212/752-5958                                         LONDON          
                                                                HONG KONG       

                                           April 4, 1997


Alexion Pharmaceuticals, Inc.
25 Science Park
New Haven, Connecticut  06511

Dear Sirs:

       We refer to the Registration Statement on Form S-8 (the "Registration
Statement") to be filed with the Securities and Exchange Commission under the
Securities Act of 1933, as amended (the "Act"), on behalf of Alexion
Pharmaceuticals, Inc. (the "Company"), relating to 1,800,000 shares of the
Company's Common Stock, $.0001 par value per share (the "Shares"), to be issued
under the Company's 1992 Stock Option Plan (the "Plan").

       As counsel for the Company, we have examined such corporate records,
other documents, and such questions of law as we have considered necessary or
appropriate for the purposes of this opinion and, upon the basis of such
examination, advise you that in our opinion, all necessary corporate proceedings
by the Company have been duly taken to authorize the issuance of the Shares
pursuant to the Plan and that the Shares being registered pursuant to the
Registration Statement, when issued and paid for under the Plan in accordance
with the terms of the Plan, will be duly authorized, validly issued, fully paid
and non-assessable.

       We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement. This consent is not be construed as an admission that we
are a person whose consent is required to be filed with the Registration
Statement under the provisions of the Act.

                                           Very truly yours,

                                           /s/ Fulbright & Jaworski


                                                                   EXHIBIT 23(a)


                    CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS

As independent public accountants, we hereby consent to the incorporation by
reference in this registration statement of our report dated August 30, 1996
included in Alexion Pharmaceuticals, Inc.'s Form 10-K for the year ended July
31, 1996 and to all references to our Firm included in this registration
statement.

                                          /S/ ARTHUR ANDERSEN LLP
                                              ---------------------
                                              ARTHUR ANDERSEN LLP

Hartford, Connecticut
April 4, 1997