<ARTICLE> 5
<LEGEND>
THE FINANCIAL DATA SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED
FROM TANOX'S 10Q FOR THE THREE MONTHS ENDED MARCH 31, 2000 AND IS QUALIFIED IN
ITS ENTIRETY BY REFERENCE TO SUCH MATTERS.
</LEGEND>
<MULTIPLIER>      1,000

                             
<PERIOD-TYPE>                   3-MOS
<FISCAL-YEAR-END>                          DEC-31-2000
<PERIOD-END>                               MAR-31-2000
<CASH>                                          28,864
<SECURITIES>                                    15,428
<RECEIVABLES>                                      795
<ALLOWANCES>                                         0
<INVENTORY>                                          0
<CURRENT-ASSETS>                                45,254
<PP&E>                                          11,637
<DEPRECIATION>                                 (4,849)
<TOTAL-ASSETS>                                  53,497
<CURRENT-LIABILITIES>                            8,344
<BONDS>                                              0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                           340
<OTHER-SE>                                      34,813
<TOTAL-LIABILITY-AND-EQUITY>                    53,497
<SALES>                                              0
<TOTAL-REVENUES>                                   149
<CGS>                                                0
<TOTAL-COSTS>                                        0
<OTHER-EXPENSES>                                 6,594
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                                 200
<INCOME-PRETAX>                                 (5,967)
<INCOME-TAX>                                         0
<INCOME-CONTINUING>                             (5,967)
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                   (5,967)
<EPS-BASIC>                                     (0.18)
<EPS-DILUTED>                                   (0.18)