<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM CHIRON
CORPORATION'S 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>                                 1,076,688<F1><F5>
<RECEIVABLES>                                  185,748<F5>
<ALLOWANCES>                                    18,160<F5>
<INVENTORY>                                     79,862<F5>
<CURRENT-ASSETS>                             1,630,942<F5>
<PP&E>                                         501,183<F5>
<DEPRECIATION>                               (198,102)<F5>
<TOTAL-ASSETS>                               2,524,264<F5>
<CURRENT-LIABILITIES>                          557,435<F5>
<BONDS>                                        338,158<F2>
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         1,799
<OTHER-SE>                                   1,544,003<F3>
<TOTAL-LIABILITY-AND-EQUITY>                 2,524,264<F5>
<SALES>                                        399,251
<TOTAL-REVENUES>                               736,673
<CGS>                                          174,803<F5><F6>
<TOTAL-COSTS>                                  174,803<F5><F6>
<OTHER-EXPENSES>                               334,412<F4><F5><F6>
<LOSS-PROVISION>                                14,370
<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-BASIC>                                       2.95
<EPS-DILUTED>                                     2.90
<FN>
<F1>CONSISTS OF 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, AND 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>DURING THE SECOND QUARTER OF 1999, THE COMPANY COMPLETED THE IMPLEMENTATION
OF AN INTEGRATED INFORMATION SYSTEM. AS A RESULT, CERTAIN PREVIOUSLY
REPORTED AMOUNTS HAVE BEEN RECLASSIFIED TO CONFORM WITH THE DECEMBER 31, 1999
PRESENTATION.
<F6>DURING THE FOURTH QUARTER OF 1999, THE COMPANY RECLASSIFIED THIRD PARTY
CONTRACT MANUFACTURING EXPENSES TO "OTHER EXPENSES", WHICH WERE PREVIOUSLY
CLASSIFIED AS "COST OF SALES." AS A RESULT, CERTAIN PREVIOUSLY REPORTED AMOUNTS
HAVE BEEN RECLASSIFIED TO CONFORM WITH THE DECEMBER 31, 1999 PRESENTATION.
<F7>THE ACTUAL FISCAL YEAR END WAS JAN-03-199.  FOR PRESENTATIONAL PURPOSES,
DATES USED IN THE CONSOLIDATED FINANCIAL STATEMENTS AND NOTES REFER TO THE
FISCAL MONTH END.
</FN>


</TABLE>