
<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM ILLUMINA,
INC.'S BALANCE SHEETS AS OF DECEMBER 31, 1998 AND DECEMBER 31, 1999 AND RELATED
STATEMENTS OF OPERATIONS STOCKHOLDERS' EQUITY, AND CASH FLOWS FOR THE PERIOD
FROM APRIL 28, 1998 (INCEPTION) TO DECEMBER 31, 1998 AND FOR THE YEAR ENDED
DECEMBER 31, 1999 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH
FINANCIAL STATEMENTS.
</LEGEND>

<S>                             <C>                     <C>
<PERIOD-TYPE>                   8-MOS                   YEAR
<FISCAL-YEAR-END>                          DEC-31-1998             DEC-31-1999
<PERIOD-START>                             APR-28-1998             JAN-01-1999
<PERIOD-END>                               DEC-31-1998             DEC-31-1999
<CASH>                                       8,233,729              21,164,114
<SECURITIES>                                         0              11,924,163
<RECEIVABLES>                                        0                  49,818
<ALLOWANCES>                                         0                       0
<INVENTORY>                                          0                       0
<CURRENT-ASSETS>                             8,408,249              33,493,045
<PP&E>                                           1,000                 296,286
<DEPRECIATION>                                       0                 (4,972)
<TOTAL-ASSETS>                               8,557,415              33,894,658
<CURRENT-LIABILITIES>                          177,170                 612,408
<BONDS>                                              0                       0
<PREFERRED-MANDATORY>                                0                       0
<PREFERRED>                                  9,397,998              37,397,998
<COMMON>                                        34,560                  51,391
<OTHER-SE>                                  (1,052,313)             (5,417,139)
<TOTAL-LIABILITY-AND-EQUITY>                 8,557,415              33,894,658
<SALES>                                              0                       0
<TOTAL-REVENUES>                                     0                 474,026
<CGS>                                                0                       0
<TOTAL-COSTS>                                1,194,168               6,354,568
<OTHER-EXPENSES>                                     0                       0
<LOSS-PROVISION>                                     0                       0
<INTEREST-EXPENSE>                                   0                  48,517
<INCOME-PRETAX>                             (1,145,620)             (5,517,645)
<INCOME-TAX>                                         0                       0
<INCOME-CONTINUING>                         (1,145,620)             (5,517,645)
<DISCONTINUED>                                       0                       0
<EXTRAORDINARY>                                      0                       0
<CHANGES>                                            0                       0
<NET-INCOME>                                (1,145,620)             (5,517,645)
<EPS-BASIC>                                      (1.71)                  (3.91)
<EPS-DILUTED>                                    (1.71)                  (3.91)


</TABLE>
