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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                             ----------------------

                                    FORM 8-K

                             ----------------------


                                 CURRENT REPORT
                     PURSUANT TO SECTION 13 OR 15(D) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


Date of Report (Date of earliest event reported)           DECEMBER 30, 1998
                                                 ---------------------------


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


       DELAWARE                      0-27756                      13-3648318
(State or Other Jurisdiction      (Commission                   (IRS Employer
     of Incorporation)             File Number)              Identification No.)



     25 SCIENCE PARK, NEW HAVEN, CT                               06511
(Address of Principal Executive Offices)                       (Zip Code)



Registrant's telephone number, including area code:       (203) 776-1790


                                 NOT APPLICABLE

          (Former Name or Former Address, if Changed Since Last Report)





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ITEM 5.  OTHER EVENTS

         On December 30, 1998, Alexion Pharmaceuticals, Inc. issued the press 
release filed herewith as Exhibit 99.



ITEM 7.  FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS.

         (C)  EXHIBITS.

         99       Press Release dated December 30, 1998.







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                                   SIGNATURES


         Pursuant to the requirements of the Securities Exchange Act of 1934,
the registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.



                            ALEXION PHARMACEUTICALS, INC.



Date: December 30, 1998     By:    /S/ LEONARD BELL
                                   -------------------

                            Name:  Leonard Bell, M.D.
                            Title: President, Chief Executive Officer, Secretary
                                   and Treasurer









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                                                             EXHIBIT 99

IMMEDIATE RELEASE     CONTACT: Leonard Bell, M.D.            Juliane Snowden
                                President and CEO            Tariq Jawad
                                Alexion Pharmaceuticals      Dewe Rogerson Inc.
                                203/776-1790                 212/688-6840

 ALEXION SIGNS LETTER OF INTENT TO REACQUIRE TYCO STAKE IN XENOTRANSPLANTATION 
       PROGRAM
- -To Reacquire Full Rights to Spinal Cord Repair, Parkinson's Disease and Other 
Transplantation Products-

NEW HAVEN, Conn., December 30, 1998 -- Alexion Pharmaceuticals, Inc. (Nasdaq:
ALXN) today announced that it has signed a letter of intent to reacquire the
rights to all aspects of its xenotransplantation program that had been obtained
by Tyco International Ltd. (Tyco), when Tyco acquired United States Surgical
Corporation (USSC) earlier this year. Tyco and Alexion will proceed to complete
the transaction. In addition, Tyco's 7% equity stake in Alexion has been sold to
three existing Alexion shareholders.

"Since Tyco's acquisition of USSC, it has been clear that Tyco's involvement in
the xenotransplantation program was not in line with their corporate business
objectives. We believe that our reacquisition of their rights to this technology
platform is a win-win outcome for both Tyco and Alexion," said Leonard Bell,
M.D., President and Chief Executive Officer of Alexion. "We are excited to have
been positioned to regain complete ownership of all rights to our
xenotransplantation portfolio. This is particularly exciting in light of recent
announcements regarding spinal cord repair products that we are co-developing
with scientists at Yale University, and Parkinson's Disease products that we are
developing in collaboration with researchers at Harvard. Importantly, we believe
that acquisition of the specialized transgenic pig farming facility, previously
purchased by USSC, will allow Alexion to exercise more control over the rate of
development of our product candidates. We will be positioned to take full
advantage of the 6 million dollars in awards that this program has garnered from
the Federal NIST Advanced Technology Program (ATP) to aggressively pursue our
xenotransplantation program goals."

"Finally, we are particularly grateful for the continued support and confidence
of our existing shareholders," said Dr. Bell.

In October 1998, Alexion announced that it had accepted the most recent of three
ATP awards, a three-year grant to fund the Company's xenotransplantation
efforts. On November 10th, 1998, Alexion announced that researchers from the
Harvard Medical School and Alexion had obtained data showing restoration of
brain function obtained following the first xenotransplantation of transgenic
pig nerve cells (neurons) in an animal model of Parkinson's Disease. On November
12th, researchers from the Yale University School of Medicine and Alexion
reported data showing that its transgenic pig cells form a sheath around damaged
neurons in animals whose spinal cords were surgically severed, and that the
spinal cords that had received the pig cell xenotransplants showed restoration
of normal nerve signal conduction.

Xenotransplantation refers to the transplantation of non-human organs and
tissues into human patients. The use of non-human tissues, or xenografts, in
transplantation has generally not been feasible due to the rapid (hyperacute)
rejection of these non-human tissues by the human immune system. Since the
hyperacute rejection process is largely mediated by the activity of the
complement system, Alexion is pioneering a double-barreled approach to the
problem of hyperacute rejection. This proprietary approach involves the





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creation of transgenic pigs that have been genetically altered so as to reduce
or eliminate the expression of non-human sugars that are targets of complement
attack and that have been further engineered to express human complement
inhibitor proteins that provide a shield against the immune attack involved in
hyperacute rejection.

Several thousand patients die each year in the U.S. as a result of inadequate
organ supply. The demand for organ transplantation is increasing at an annual
rate of 15-20%. However, the supply of human donor organs has not increased
substantially. Published articles estimate that approximately 100,000 patients
yearly would medically benefit from organ transplantation if sufficient organs
were available.

Alexion Pharmaceuticals, Inc. was founded in 1992 and is engaged in the
development of selective immunotherapeutic drugs that generally are designed to
inhibit the disease-causing segments of the immune system while preserving the
disease-preventing aspects of the immune system. The Company is developing three
technology platforms: C5 Complement Inhibitors and Apogen T-Cell Therapeutics
which together target severe cardiovascular and autoimmune disorders; and
xenografts for organ transplantation.

THIS NEWS RELEASE CONTAINS FORWARD-LOOKING STATEMENTS. SUCH STATEMENTS ARE
SUBJECT TO CERTAIN FACTORS WHICH MAY CAUSE ALEXION'S PLANS TO DIFFER OR RESULTS
TO VARY FROM THOSE EXPECTED INCLUDING UNEXPECTED PRE-CLINICAL OR CLINICAL
RESULTS, THE NEED FOR ADDITIONAL RESEARCH AND TESTING, DELAYS IN MANUFACTURING,
ACCESS TO CAPITAL AND FUNDING, DELAYS AND ADVERSE CHANGES IN DEVELOPMENT OF
COMMERCIAL RELATIONSHIPS AND A VARIETY OF RISKS SET FORTH FROM TIME TO TIME IN
ALEXION'S FILINGS WITH THE SECURITIES AND EXCHANGE COMMISSION, INCLUDING BUT NOT
LIMITED TO THE RISKS DISCUSSED IN ALEXION'S ANNUAL REPORT ON FORM 1O-K FOR THE
YEAR ENDED JULY 31, 1998. ALEXION UNDERTAKES NO OBLIGATION TO PUBLICLY RELEASE
RESULTS OF ANY OF THESE FORWARD-LOOKING STATEMENTS WHICH MAY BE MADE TO REFLECT
EVENTS OR CIRCUMSTANCES AFTER THE DATE HEREOF OR TO REFLECT THE OCCURRENCE OF
UNANTICIPATED EVENTS.