<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM CHIRON
CORPORATION'S CONSOLIDATED BALANCE SHEET DATED DECEMBER 31, 1999 AND
CONSOLIDATED STATEMENT OF OPERATIONS FOR THE YEAR ENDED DECEMBER 31, 1999
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-31-1999<F6>
<PERIOD-START>                             JAN-01-1999
<PERIOD-END>                               DEC-31-1999<F6>
<CASH>                                         363,865
<SECURITIES>                                 1,190,922<F1>
<RECEIVABLES>                                  196,081<F7>
<ALLOWANCES>                                    16,998
<INVENTORY>                                     84,724
<CURRENT-ASSETS>                             1,339,300
<PP&E>                                         521,401
<DEPRECIATION>                                 222,566
<TOTAL-ASSETS>                               2,458,769
<CURRENT-LIABILITIES>                          612,931
<BONDS>                                         96,958<F2>
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         1,819
<OTHER-SE>                                   1,691,018<F3>
<TOTAL-LIABILITY-AND-EQUITY>                 2,458,769
<SALES>                                        421,677
<TOTAL-REVENUES>                               762,646
<CGS>                                          184,414<F4>
<TOTAL-COSTS>                                  184,414<F4>
<OTHER-EXPENSES>                               314,978<F4><F5>
<LOSS-PROVISION>                                13,494
<INTEREST-EXPENSE>                              23,892
<INCOME-PRETAX>                                156,644
<INCOME-TAX>                                    28,240
<INCOME-CONTINUING>                            128,404
<DISCONTINUED>                                  32,173
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                   160,577
<EPS-BASIC>                                       0.89
<EPS-DILUTED>                                     0.86
<FN>
<F1>CONSISTS OF SHORT-TERM AND NONCURRENT INVESTMENTS IN MARKETABLE DEBT AND
EQUITY SECURITIES.
<F2>CONSISTS OF CONVERTIBLE SUBORDINATED DEBENTURES AND NOTES PAYABLE, NET OF
CURRENT MATURITIES.
<F3>CONSISTS OF ADDITIONAL PAID-IN CAPITAL, ACCUMULATED DEFICIT, COST OF
TREASURY STOCK, AND ACCUMULATED OTHER COMPREHENSIVE INCOME.
<F4>DURING THE FOURTH QUARTER OF 1999, THE COMPANY RECLASSIFIED THIRD PARTY
CONTRACT MANUFACTURING EXPENSES IN "OTHER EXPENSES" WHICH WERE PREVIOUSLY
CLASSIFIED AS "COST OF SALES."
<F5>CONSISTS OF RESEARCH AND DEVELOPMENT, RESTRUCTURING AND REORGANIZATION
CHARGES AND OTHER OPERATING EXPENSES.
<F6>DURING THE FIRST QUARTER OF 1999, THE COMPANY CHANGED ITS FISCAL YEAR FROM
A 52 OR 53-WEEK YEAR ENDING ON THE SUNDAY NEAREST THE LAST DAY IN DECEMBER,
TO A CALENDAR YEAR ENDING ON DECEMBER 31.
<F7>CONSISTS OF ACCOUNTS RECEIVABLE AND CURRENT AND NONCURRENT PORTIONS OF NOTES
RECEIVABLE.
</FN>


</TABLE>