<TABLE> <S> <C>
<ARTICLE> 6
<LEGEND>
This schedule contains summary financial information extracted from financial
statements dated April 30, 2000 included in the Fund's Semiannual Report and is
qualified in its entirety by reference to such financial statements.
</LEGEND>
<CIK> 0000277751
<NAME> JANUS TWENTY FUND
<SERIES>
<NUMBER> 002
<NAME> JANUS TWENTY FUND
<MULTIPLIER> 1000
<CURRENCY> U.S. DOLLARS
<S> <C>
<PERIOD-TYPE> YEAR
<FISCAL-YEAR-END> OCT-31-2000
<PERIOD-START> NOV-01-1999
<PERIOD-END> APR-30-2000
<EXCHANGE-RATE> 1.000
<INVESTMENTS-AT-COST> 19,619,893
<INVESTMENTS-AT-VALUE> 35,347,371
<RECEIVABLES> 158,113
<ASSETS-OTHER> 2,151
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 35,507,635
<PAYABLE-FOR-SECURITIES> 97,514
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 45,148
<TOTAL-LIABILITIES> 142,662
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 18,561,236
<SHARES-COMMON-STOCK> 441,577
<SHARES-COMMON-PRIOR> 412,990
<ACCUMULATED-NII-CURRENT> (13,937)
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 1,090,206
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 15,727,468
<NET-ASSETS> 35,364,973
<DIVIDEND-INCOME> 37,094
<INTEREST-INCOME> 98,020
<OTHER-INCOME> 0
<EXPENSES-NET> 149,051
<NET-INVESTMENT-INCOME> (13,937)
<REALIZED-GAINS-CURRENT> 1,096,608
<APPREC-INCREASE-CURRENT> 5,021,173
<NET-CHANGE-FROM-OPS> 6,103,844
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> (79,074)
<DISTRIBUTIONS-OF-GAINS> (1,708,104)
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 63,354
<NUMBER-OF-SHARES-REDEEMED> (56,638)
<SHARES-REINVESTED> 21,871
<NET-CHANGE-IN-ASSETS> 6,571,861
<ACCUMULATED-NII-PRIOR> 79,074
<ACCUMULATED-GAINS-PRIOR> 1,701,702
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 113,828
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 150,292
<AVERAGE-NET-ASSETS> 35,242,705
<PER-SHARE-NAV-BEGIN> 69.720
<PER-SHARE-NII> (0.040)
<PER-SHARE-GAIN-APPREC> 14.680
<PER-SHARE-DIVIDEND> (0.190)
<PER-SHARE-DISTRIBUTIONS> (4.080)
<RETURNS-OF-CAPITAL> 0.000
<PER-SHARE-NAV-END> 80.090
<EXPENSE-RATIO> 0.860
</TABLE>
