<TABLE> <S> <C>
<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM CEPHALON,
INC.'S FORM 10-Q FOR THE QUARTER ENDED JUNE 30, 2000 AND IS QUALIFIED IN ITS
ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<S> <C>
<PERIOD-TYPE> 9-MOS
<FISCAL-YEAR-END> DEC-31-1999
<PERIOD-START> JAN-01-2000
<PERIOD-END> SEP-30-2000
<CASH> 16,300,000
<SECURITIES> 111,040,000
<RECEIVABLES> 13,767,000
<ALLOWANCES> 0
<INVENTORY> 16,843,000
<CURRENT-ASSETS> 160,704,000
<PP&E> 42,512,000
<DEPRECIATION> 16,474,000
<TOTAL-ASSETS> 188,436,000
<CURRENT-LIABILITIES> 24,240,000
<BONDS> 13,514,000
0
25,000
<COMMON> 349,000
<OTHER-SE> 150,130,000
<TOTAL-LIABILITY-AND-EQUITY> 188,436,000
<SALES> 47,963,000
<TOTAL-REVENUES> 60,626,000
<CGS> 9,185,000
<TOTAL-COSTS> 9,185,000
<OTHER-EXPENSES> 43,594,000
<LOSS-PROVISION> 0
<INTEREST-EXPENSE> 3,377,000
<INCOME-PRETAX> (28,189,000)
<INCOME-TAX> 0
<INCOME-CONTINUING> (28,189,000)
<DISCONTINUED> 0
<EXTRAORDINARY> 0
<CHANGES> 0
<NET-INCOME> (34,986,000)
<EPS-BASIC> (1.04)
<EPS-DILUTED> (1.04)
</TABLE>