<ARTICLE> 5 <CIK> 0000822818 <NAME> CLEAN HARBORS <MULTIPLIER> 1,000 <PERIOD-TYPE> 6-MOS <FISCAL-YEAR-END> DEC-31-1999 <PERIOD-START> JAN-01-1999 <PERIOD-END> JUN-30-1999 <CASH> 3,500 <SECURITIES> 1,148 <RECEIVABLES> 42,688 <ALLOWANCES> 1,258 <INVENTORY> 2,796 <CURRENT-ASSETS> 51,320 <PP&E> 134,646 <DEPRECIATION> 76,901 <TOTAL-ASSETS> 146,191 <CURRENT-LIABILITIES> 35,978 <BONDS> 74,545 <PREFERRED-MANDATORY> 0 <PREFERRED> 1 <COMMON> 106 <OTHER-SE> 146,084 <TOTAL-LIABILITY-AND-EQUITY> 146,191 <SALES> 0 <TOTAL-REVENUES> 95,766 <CGS> 0 <TOTAL-COSTS> 70,907 <OTHER-EXPENSES> 17,748 <LOSS-PROVISION> 342 <INTEREST-EXPENSE> 4,429 <INCOME-PRETAX> (1,957) <INCOME-TAX> 180 <INCOME-CONTINUING> (2,137) <DISCONTINUED> 0 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> (2,137) <EPS-BASIC> (0.22) <EPS-DILUTED> (0.22)