<ARTICLE>           5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THERMO
INSTRUMENT SYSTEMS INC.'S QUARTERLY REPORT ON FORM 10-Q FOR THE PERIOD ENDED
JULY 3, 1999 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL
STATEMENTS.
</LEGEND>
<MULTIPLIER>        1,000

                              
<PERIOD-TYPE>                                 6-MOS
<FISCAL-YEAR-END>                             JAN-01-2000
<PERIOD-END>                                  JUL-03-1999
<CASH>                                                223,949
<SECURITIES>                                                0
<RECEIVABLES>                                         490,465
<ALLOWANCES>                                           32,389
<INVENTORY>                                           348,282
<CURRENT-ASSETS>                                    1,381,290
<PP&E>                                                420,592
<DEPRECIATION>                                        138,339
<TOTAL-ASSETS>                                      2,854,263
<CURRENT-LIABILITIES>                                 845,018
<BONDS>                                               613,444
<PREFERRED-MANDATORY>                                       0
<PREFERRED>                                                 0
<COMMON>                                               12,288
<OTHER-SE>                                            916,062
<TOTAL-LIABILITY-AND-EQUITY>                        2,854,263
<SALES>                                               999,213
<TOTAL-REVENUES>                                      999,213
<CGS>                                                 541,876
<TOTAL-COSTS>                                         541,876
<OTHER-EXPENSES>                                       76,840
<LOSS-PROVISION>                                        2,681
<INTEREST-EXPENSE>                                     25,656
<INCOME-PRETAX>                                        72,360
<INCOME-TAX>                                           33,221
<INCOME-CONTINUING>                                    31,434
<DISCONTINUED>                                              0
<EXTRAORDINARY>                                             0
<CHANGES>                                                   0
<NET-INCOME>                                           31,434
<EPS-BASIC>                                            0.26
<EPS-DILUTED>                                            0.24