<ARTICLE> 9 <CIK> 0000799166 <NAME> MASSBANK CORP. <MULTIPLIER> 1,000 <PERIOD-TYPE> 9-MOS <FISCAL-YEAR-END> DEC-31-1999 <PERIOD-START> JAN-01-1999 <PERIOD-END> SEP-30-1999 <CASH> 7,687 <INT-BEARING-DEPOSITS> 3,790 <FED-FUNDS-SOLD> 111,096 <TRADING-ASSETS> 6,033 <INVESTMENTS-HELD-FOR-SALE> 455,941 <INVESTMENTS-CARRYING> 230 <INVESTMENTS-MARKET> 230 <LOANS> 330,022 <ALLOWANCE> (2,506) <TOTAL-ASSETS> 935,086 <DEPOSITS> 825,960 <SHORT-TERM> 1,517 <LIABILITIES-OTHER> 4,116 <LONG-TERM> 625 <PREFERRED-MANDATORY> 0 <PREFERRED> 0 <COMMON> 7,392 <OTHER-SE> 95,476 <TOTAL-LIABILITIES-AND-EQUITY> 935,086 <INTEREST-LOAN> 16,994 <INTEREST-INVEST> 20,698 <INTEREST-OTHER> 5,756 <INTEREST-TOTAL> 43,448 <INTEREST-DEPOSIT> 24,839 <INTEREST-EXPENSE> 24,839 <INTEREST-INCOME-NET> 18,609 <LOAN-LOSSES> 125 <SECURITIES-GAINS> 3,261 <EXPENSE-OTHER> 9,356 <INCOME-PRETAX> 13,536 <INCOME-PRE-EXTRAORDINARY> 13,536 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 8,562 <EPS-BASIC> 2.52 <EPS-DILUTED> 2.44 <YIELD-ACTUAL> 2.69 <LOANS-NON> 790 <LOANS-PAST> 0 <LOANS-TROUBLED> 0 <LOANS-PROBLEM> 790 <ALLOWANCE-OPEN> 2,450 <CHARGE-OFFS> (73) <RECOVERIES> 4 <ALLOWANCE-CLOSE> 2,506 <ALLOWANCE-DOMESTIC> 2,253 <ALLOWANCE-FOREIGN> 0 <ALLOWANCE-UNALLOCATED> 253