<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM CHIRON
CORPORATION CONSOLIDATED BALANCE SHEET DATED DECEMBER 31, 1998 AND CONSOLIDATED
STATEMENT OF OPERATIONS FOR THE YEAR ENDED DECEMBER 31, 1998 AND IS QUALIFIED IN
ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
       
<S>                             <C>
<PERIOD-TYPE>                   YEAR
<FISCAL-YEAR-END>                          DEC-31-1998<F7>
<PERIOD-START>                             JAN-01-1998
<PERIOD-END>                               DEC-31-1998<F7>
<CASH>                                         513,315
<SECURITIES>                                 1,076,699<F1>
<RECEIVABLES>                                  185,288
<ALLOWANCES>                                    16,190
<INVENTORY>                                     79,869
<CURRENT-ASSETS>                             1,631,639
<PP&E>                                         501,190
<DEPRECIATION>                                 197,812
<TOTAL-ASSETS>                               2,524,255
<CURRENT-LIABILITIES>                          557,418
<BONDS>                                        338,158<F2>
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         1,799
<OTHER-SE>                                   1,544,003<F3>
<TOTAL-LIABILITY-AND-EQUITY>                 2,524,255
<SALES>                                        399,251
<TOTAL-REVENUES>                               736,673
<CGS>                                          178,063
<TOTAL-COSTS>                                  178,063
<OTHER-EXPENSES>                               333,279<F4>
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                              24,673
<INCOME-PRETAX>                                 94,983
<INCOME-TAX>                                    18,985
<INCOME-CONTINUING>                             75,998
<DISCONTINUED>                                 448,115
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                   524,113
<EPS-PRIMARY>                                     2.95<F5>
<EPS-DILUTED>                                     2.90<F6>
<FN>
<F7>ACTUAL FISCAL YEAR END WAS JAN-03-1999. FOR PRESENTATION PURPOSES, DATES USED
IN THE CONSOLIDATED FINANCIAL STATEMENTS AND NOTES REFER TO THE FISCAL MONTH
END.
<F1>CONSISTS OF BOTH SHORT-TERM AND NONCURRENT INVESTMENTS IN MARKETABLE DEBT
SECURITIES.
<F2>CONSISTS OF CONVERTIBLE SUBORDINATED DEBENTURES, CAPITAL LEASE OBLIGATIONS AND
NOTES PAYABLE, NET OF CURRENT MATURITIES.
<F3>CONSISTS OF ADDITIONAL PAID-IN CAPITAL, ACCUMULATED DEFICIT, ACCUMULATED 
OTHER COMPREHENSIVE INCOME.
<F4>CONSISTS OF RESEARCH AND DEVELOPMENT, WRITE-OFF OF PURCHASED IN-PROCESS
TECHNOLOGIES, RESTRUCTURING AND REORGANIZATION CHARGES AND OTHER OPERATING
EXPENSES.
<F5>REPRESENTS BASIC NET INCOME PER SHARE. BASIC INCOME PER SHARE FROM CONTINUING
OPERATIONS AND BASIC INCOME PER SHARE FROM DISCONTINUED OPERATIONS WERE $0.43
AND $2.52, RESPECTIVELY.
<F6>REPRESENTS DILUTED NET INCOME PER SHARE. DILUTED INCOME PER SHARE FROM
CONTINUING OPERATIONS AND DILUTED INCOME PER SHARE FROM DISCONTINUED OPERATIONS
WERE $0.42 AND $2.48, RESPECTIVELY.
</FN>
        

</TABLE>