<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM CHIRON
CORPORATION'S UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEET DATED JUNE 30,
1998 AND UNAUDITED CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS FOR THE 
SIX MONTHS ENDED JUNE 30, 1998 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE
TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
       
<S>                             <C>
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1998<F5>
<PERIOD-START>                             JAN-01-1998
<PERIOD-END>                               JUN-30-1998<F5>
<CASH>                                         158,120
<SECURITIES>                                   254,859<F1>
<RECEIVABLES>                                  328,132
<ALLOWANCES>                                         0
<INVENTORY>                                    170,231
<CURRENT-ASSETS>                               848,427
<PP&E>                                         765,364
<DEPRECIATION>                                 283,432
<TOTAL-ASSETS>                               1,802,840
<CURRENT-LIABILITIES>                          378,088
<BONDS>                                        402,312<F2>
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         1,775
<OTHER-SE>                                     987,615<F3>
<TOTAL-LIABILITY-AND-EQUITY>                 1,802,840
<SALES>                                        442,042
<TOTAL-REVENUES>                               574,437
<CGS>                                          191,418
<TOTAL-COSTS>                                  191,418
<OTHER-EXPENSES>                               212,223<F4>
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                              13,347
<INCOME-PRETAX>                                 19,154
<INCOME-TAX>                                     4,618
<INCOME-CONTINUING>                             14,536
<DISCONTINUED>                                  65,332
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                    79,868
<EPS-PRIMARY>                                     0.45<F6>
<EPS-DILUTED>                                     0.44<F7>
<FN>
<F5>ACTUAL FISCAL YEAR END WILL BE, AND PERIOD END WAS, JAN-03-1999 AND
JUN-28-1998, RESPECTIVELY. 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 AND ACCUMULATED 
OTHER COMPREHENSIVE LOSS.
<F4>CONSISTS OF RESEARCH AND DEVELOPMENT, WRITE-OFF OF PURCHASED IN-PROCESS 
TECHNOLOGIES, RESTRUCTURING AND REORGANIZATION CHARGES AND OTHER OPERATING EXPENSES.
<F6>REPRESENTS BASIC NET INCOME PER SHARE. BASIC INCOME PER SHARE FROM CONTINUING
OPERATIONS AND BASIC INCOME PER SHARE FROM DISCONTINUED OPERATIONS WERE $0.08
AND $0.37, RESPECTIVELY.
<F7>REPRESENTS DILUTED NET INCOME PER SHARE. DILUTED INCOME PER SHARE FROM
CONTINUING OPERATIONS AND DILUTED INCOME PER SHARE FROM DISCONTINUED OPERATIONS
WERE $0.08 AND $0.36, RESPECTIVELY.
</FN>
        

</TABLE>