<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
CONSOLIDATED FINANCIAL STATEMENTS OF BIOGEN, INC. AND SUBSIDIARIES FOR THE YEAR
ENDED DECEMBER 31, 1999 AND IS QUALIFIED IN ITS ENTIRETY TO SUCH ANNUAL REPORT
ON FORM 10K FOR THE PERIOD ENDED DECEMBER 31, 1999.
</LEGEND>
<MULTIPLIER> 1,000
<CURRENCY> U.S. DOLLARS

                             
<PERIOD-TYPE>                   YEAR
<FISCAL-YEAR-END>                          DEC-31-1999
<PERIOD-START>                             JAN-01-1999
<PERIOD-END>                               DEC-31-1999
<EXCHANGE-RATE>                                      1
<CASH>                                          56,920
<SECURITIES>                                   597,619
<RECEIVABLES>                                  139,005
<ALLOWANCES>                                     1,642
<INVENTORY>                                     40,031
<CURRENT-ASSETS>                               910,226
<PP&E>                                         351,566
<DEPRECIATION>                                 111,789
<TOTAL-ASSETS>                               1,277,973
<CURRENT-LIABILITIES>                          190,270
<BONDS>                                         52,073
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         1,507
<OTHER-SE>                                     978,023
<TOTAL-LIABILITY-AND-EQUITY>                 1,277,973
<SALES>                                        620,636
<TOTAL-REVENUES>                               794,435
<CGS>                                           96,903
<TOTAL-COSTS>                                  111,005
<OTHER-EXPENSES>                               367,179
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                               4,639
<INCOME-PRETAX>                                329,016
<INCOME-TAX>                                   108,566
<INCOME-CONTINUING>                            220,450
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                   220,450
<EPS-BASIC>                                       1.47
<EPS-DILUTED>                                     1.40