<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM ARIBA INC'S
QUARTERLY REPORT ON FORM 10-Q FOR THE PERIOD ENDED DECEMBER 31, 1999 AND IS
QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000

                             
<PERIOD-TYPE>                   3-MOS
<FISCAL-YEAR-END>                          SEP-30-2000
<PERIOD-START>                             OCT-01-1999
<PERIOD-END>                               DEC-31-1999
<CASH>                                          42,568
<SECURITIES>                                   118,832
<RECEIVABLES>                                    8,840
<ALLOWANCES>                                      (20)
<INVENTORY>                                          0
<CURRENT-ASSETS>                               121,873
<PP&E>                                          16,766
<DEPRECIATION>                                   2,660
<TOTAL-ASSETS>                                 190,820
<CURRENT-LIABILITIES>                           73,328
<BONDS>                                              0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                           184
<OTHER-SE>                                     116,652
<TOTAL-LIABILITY-AND-EQUITY>                   190,820
<SALES>                                         15,784
<TOTAL-REVENUES>                                23,479
<CGS>                                              321
<TOTAL-COSTS>                                    3,442
<OTHER-EXPENSES>                                32,357
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                                  44
<INCOME-PRETAX>                               (10,261)
<INCOME-TAX>                                        73
<INCOME-CONTINUING>                           (10,334)
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                  (10,334)
<EPS-BASIC>                                     (0.13)
<EPS-DILUTED>                                   (0.13)