<ARTICLE> 9 <CIK> 0000799166 <NAME> MASSBANK CORP. <MULTIPLIER> 1,000 <PERIOD-TYPE> 9-MOS <FISCAL-YEAR-END> DEC-31-1998 <PERIOD-START> JAN-01-1998 <PERIOD-END> SEP-30-1998 <CASH> 7,473 <INT-BEARING-DEPOSITS> 1,848 <FED-FUNDS-SOLD> 164,958 <TRADING-ASSETS> 1,129 <INVESTMENTS-HELD-FOR-SALE> 426,539 <INVESTMENTS-CARRYING> 358 <INVESTMENTS-MARKET> 358 <LOANS> 296,949 <ALLOWANCE> (2,425) <TOTAL-ASSETS> 934,458 <DEPOSITS> 811,666 <SHORT-TERM> 1,522 <LIABILITIES-OTHER> 10,121 <LONG-TERM> 781 <PREFERRED-MANDATORY> 0 <PREFERRED> 0 <COMMON> 7,371 <OTHER-SE> 102,997 <TOTAL-LIABILITIES-AND-EQUITY> 934,458 <INTEREST-LOAN> 15,880 <INTEREST-INVEST> 22,719 <INTEREST-OTHER> 6,514 <INTEREST-TOTAL> 45,113 <INTEREST-DEPOSIT> 25,786 <INTEREST-EXPENSE> 25,786 <INTEREST-INCOME-NET> 19,327 <LOAN-LOSSES> 105 <SECURITIES-GAINS> 1,858 <EXPENSE-OTHER> 9,246 <INCOME-PRETAX> 13,119 <INCOME-PRE-EXTRAORDINARY> 13,119 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 8,235 <EPS-PRIMARY> 2.32 <EPS-DILUTED> 2.23 <YIELD-ACTUAL> 2.85 <LOANS-NON> 1,406 <LOANS-PAST> 0 <LOANS-TROUBLED> 0 <LOANS-PROBLEM> 1,406 <ALLOWANCE-OPEN> 2,334 <CHARGE-OFFS> (32) <RECOVERIES> 18 <ALLOWANCE-CLOSE> 2,425 <ALLOWANCE-DOMESTIC> 2,119 <ALLOWANCE-FOREIGN> 0 <ALLOWANCE-UNALLOCATED> 306