<ARTICLE>           5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THERMEDICS
DETECTION INC.'S REPORT ON FORM 10-Q FOR THE PERIOD ENDED OCTOBER 3, 1998 AND IS
QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER>        1,000
       
                              
<PERIOD-TYPE>                                 9-MOS
<FISCAL-YEAR-END>                             JAN-02-1999
<PERIOD-END>                                  OCT-03-1998
<CASH>                                                 33,814
<SECURITIES>                                                0
<RECEIVABLES>                                          17,007
<ALLOWANCES>                                            1,016
<INVENTORY>                                            16,871
<CURRENT-ASSETS>                                       72,987
<PP&E>                                                 12,241
<DEPRECIATION>                                          7,834
<TOTAL-ASSETS>                                        133,610
<CURRENT-LIABILITIES>                                  17,602
<BONDS>                                                     0
<PREFERRED-MANDATORY>                                       0
<PREFERRED>                                                 0
<COMMON>                                                1,932
<OTHER-SE>                                            114,076
<TOTAL-LIABILITY-AND-EQUITY>                          133,610
<SALES>                                                57,942
<TOTAL-REVENUES>                                       71,234
<CGS>                                                  25,881
<TOTAL-COSTS>                                          32,247
<OTHER-EXPENSES>                                        7,426
<LOSS-PROVISION>                                          201
<INTEREST-EXPENSE>                                        303
<INCOME-PRETAX>                                        11,491
<INCOME-TAX>                                            4,539
<INCOME-CONTINUING>                                     6,952
<DISCONTINUED>                                              0
<EXTRAORDINARY>                                             0
<CHANGES>                                                   0
<NET-INCOME>                                            6,952
<EPS-PRIMARY>                                            0.36
<EPS-DILUTED>                                            0.36