Exhibit 4.2

                        ALEXION PHARMACEUTICALS, INC.
                           STOCK OPTION AGREEMENT
                           ----------------------


        AGREEMENT made as of the ____ day of _________ 1998 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 for Outside Directors (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 as an incentive stock option ("NSO") 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                 Incremental     Cumulative
    Years of Continuous  Percentage of   Percentage of
    Employment/          Option          Option
    Service              Exercisable     Exercisable
    -------------------  -------------   -------------
       Less than 1          0%              0%
                 1          33 1/3%         33 1/3%
                 2          33 1/3%         66 2/3%
                 3          33 1/3%         100%

No share 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 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 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 
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, 
unless sooner terminated under the terns 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 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 opinion



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 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 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.

        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 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