<ARTICLE> 9
<CIK> 0000799166
<NAME> MASSBANK CORP.
<MULTIPLIER> 1,000
       
                             
<PERIOD-TYPE>                   12-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-START>                             JAN-01-1998
<PERIOD-END>                               DEC-31-1998
<CASH>                                           7,038
<INT-BEARING-DEPOSITS>                           2,033
<FED-FUNDS-SOLD>                               148,207
<TRADING-ASSETS>                                30,793
<INVESTMENTS-HELD-FOR-SALE>                    418,126
<INVESTMENTS-CARRYING>                             354
<INVESTMENTS-MARKET>                               354
<LOANS>                                        304,989
<ALLOWANCE>                                    (2,450)
<TOTAL-ASSETS>                                 946,625
<DEPOSITS>                                     824,031
<SHORT-TERM>                                     1,438
<LIABILITIES-OTHER>                             10,042
<LONG-TERM>                                        625
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         7,384
<OTHER-SE>                                     103,105
<TOTAL-LIABILITIES-AND-EQUITY>                 946,625
<INTEREST-LOAN>                                 21,434
<INTEREST-INVEST>                               29,625
<INTEREST-OTHER>                                 8,775
<INTEREST-TOTAL>                                59,834
<INTEREST-DEPOSIT>                              34,320
<INTEREST-EXPENSE>                              34,320
<INTEREST-INCOME-NET>                           25,514
<LOAN-LOSSES>                                      193
<SECURITIES-GAINS>                               2,893
<EXPENSE-OTHER>                                 12,515
<INCOME-PRETAX>                                 17,396
<INCOME-PRE-EXTRAORDINARY>                      17,396
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                    10,914
<EPS-PRIMARY>                                     3.09
<EPS-DILUTED>                                     2.97
<YIELD-ACTUAL>                                    2.81
<LOANS-NON>                                      1,004
<LOANS-PAST>                                         0
<LOANS-TROUBLED>                                     0
<LOANS-PROBLEM>                                  1,004
<ALLOWANCE-OPEN>                                 2,334
<CHARGE-OFFS>                                    (103)
<RECOVERIES>                                        26
<ALLOWANCE-CLOSE>                                2,450
<ALLOWANCE-DOMESTIC>                             1,966
<ALLOWANCE-FOREIGN>                                  0
<ALLOWANCE-UNALLOCATED>                            484