<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM CHIRON
CORPORATION'S UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEET DATED MARCH 31,
1999 AND UNAUDITED CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS FOR THE THREE
MONTHS ENDED MARCH 31, 1999 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO
SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000

<S>                             <C>
<PERIOD-TYPE>                   3-MOS
<FISCAL-YEAR-END>                          DEC-31-1999<F5>
<PERIOD-START>                             JAN-01-1999
<PERIOD-END>                               MAR-31-1999<F5>
<CASH>                                          69,146
<SECURITIES>                                 1,368,279<F1>
<RECEIVABLES>                                  184,032
<ALLOWANCES>                                         0
<INVENTORY>                                     80,842
<CURRENT-ASSETS>                             1,115,743
<PP&E>                                         526,089
<DEPRECIATION>                                 208,588
<TOTAL-ASSETS>                               2,373,340
<CURRENT-LIABILITIES>                          385,470
<BONDS>                                        339,259<F2>
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         1,815
<OTHER-SE>                                   1,570,453<F3>
<TOTAL-LIABILITY-AND-EQUITY>                 2,373,340
<SALES>                                         92,967
<TOTAL-REVENUES>                               175,560
<CGS>                                           43,876<F6>
<TOTAL-COSTS>                                   43,876<F6>
<OTHER-EXPENSES>                                74,988<F4><F6>
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                               5,845<F6>
<INCOME-PRETAX>                                 31,748
<INCOME-TAX>                                     8,010
<INCOME-CONTINUING>                             23,738
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                    23,738
<EPS-BASIC>                                       0.13
<EPS-DILUTED>                                     0.13
<FN>
<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 AND ACCUMULATED
OTHER COMPREHENSIVE LOSS.
<F4>CONSISTS OF RESEARCH AND DEVELOPMENT, RESRUCTURING AND REORGANIZATION CHARGES
AND OTHER OPERATING EXPENSES.
<F5>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.
<F6>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 JUNE 30, 1999 PRESENTATION.
</FN>


</TABLE>