1
                                                                     EXHIBIT 99a
                                                                     -----------
               UNAUDITED PRO FORMA COMBINED FINANCIAL INFORMATION
  
The following Unaudited Pro Forma Combined Financial Information combines the 
historical Consolidated Financial Statements of Bank of Boston and BayBanks 
giving effect to the proposed merger of Bank of Boston and BayBanks, as if it 
had been effective on September 30, 1995, with regard to the Pro Forma Combined
Balance Sheet, and as of the beginning of the periods indicated herein, with
regard to the Pro Forma Combined Statements of Income.  The proposed merger 
will be accounted for as a pooling of interests.  This information should be 
read in conjunction with the historical consolidated financial statements of 
Bank of Boston and BayBanks, including their respective notes thereto.  The 
effect of estimated acquisition and restructuring costs has been reflected in 
the pro forma combined balance sheet; however, since the estimated costs are 
nonrecurring, they have not been reflected in the pro forma combined statements
of income.  The pro forma combined financial information does not give effect 
to any anticipated cost savings in connection with the proposed merger.  The 
pro forma combined balance sheet is not necessarily indicative of the actual 
financial position that would have existed had the proposed merger with 
BayBanks been consummated on September 30, 1995 or that may exist in the future.
The pro forma combined statements of income are not necessarily indicative of 
the results that would have occurred had the proposed merger been consummated 
on the dates indicated or that may be achieved in the future.


  
                                   UNAUDITED PRO FORMA COMBINED BALANCE SHEET
                                     AT SEPTEMBER 30, 1995
  
                                          
(IN MILLIONS)                                       BANK OF                    PRO  FORMA      PRO FORMA         
                                                     BOSTON      BAYBANKS(1)  ADJUSTMENTS(1)    COMBINED      
                                                     ------      -----------  --------------    --------
                                                                                   
ASSETS                                                                             
Cash and due from  banks                            $ 2,208     $   750                        $ 2,958    
Interest bearing deposits in other banks              1,249         160                          1,409    
Federal funds sold and securities purchased 
  under agreements to resell                          1,236         189                          1,425 
Securities held to maturity                           1,765       2,190                          3,955      
Securities available for sale                         3,277         318                          3,595      
Trading account securities                              594          77                            671    
Mortgages held for sale                                 558                                        558    
Loans and leases                                     31,691       7,476                         39,167                             
Reserve for credit losses                              (704)       (154)                          (858)   
Premises and equipment                                  589         205                            794    
Due from customers on acceptances                       381           1                            382 
Other assets                                          3,239         313                          3,552
                                                    -------     -------         --------       -------
Total assets                                        $46,083     $11,525                        $57,608
                                                    =======     =======         ========       =======
                                                              
LIABILITIES AND                                                         
 STOCKHOLDERS' EQUITY                                                      
Deposits                                            $30,009     $ 9,724                        $39,733
Funds borrowed                                        8,720         732                          9,452    
Acceptances outstanding                                 381           1                            382
Other liabilities                                     1,321          97         $     83  (2)    1,501      
Notes payable                                         2,059          65                          2,124
                                                    -------     -------         --------       -------    
Total liabilities                                    42,490      10,619               83        53,192
                                                    -------     -------         --------       -------    

Stockholders'equity:                                                     
  Preferred stock                                       508                                        508      
  Common stock                                          252          39               58  (3)      349      
  Surplus                                               916         359              (58) (3)    1,217
  Retained earnings                                   1,927         508              (83) (2)    2,352
  
  Net unrealized loss on                                                             
   securities available for sale, net of tax             (6)                                        (6)                   

  Cumulative translation adjustments                     (4)                                        (4)                             
                                                    -------     -------         --------       -------    
                                                              
Total stockholders' equity                            3,593         906              (83)        4,416    
                                                    -------     -------         --------       -------    
                                                              
Total liabilities and stockholders' equity          $46,083     $11,525                        $57,608
                                                    =======     =======         ========       =======



        See Notes to Unaudited Pro Forma Combined Financial Information
   2



                          UNAUDITED PRO FORMA COMBINED STATEMENT OF INCOME SUMMARY
  

(DOLLARS IN MILLIONS, EXCEPT PER SHARE AMOUNTS)        NINE MONTHS               YEARS ENDED DECEMBER 31,
                                                          ENDED                  ------------------------
                                                      SEPT. 30, 1995         1994          1993         1992     
                                                      --------------         ----          ----         ----
                                                                                           
INTEREST INCOME:                                         
  Loans and lease financing, including fees               $ 2,860           $ 3,114       $ 2,584      $ 2,823
  Securities                                                  507               495           362          485  
  Mortgages held for sale                                      18                43            85           67   
  Federal funds sold and securities                           
    purchased under agreements to resell                      273               605           147           98   
  Deposits in other banks                                     182               119           152          191  
                                                          -------           -------       -------      -------
      Total interest income                                 3,840             4,376         3,330        3,664
                                                          -------           -------       -------      -------
INTEREST EXPENSE:                                                 
  Deposits                                                  1,348             1,301         1,177        1,640
  Funds borrowed                                              698               906           268          275  
  Notes payable                                               119               132           116           77   
                                                          -------           -------       -------      -------
      Total interest expense                                2,165             2,339         1,561        1,992
                                                          -------           -------       -------      -------
  Net interest revenue                                      1,675             2,037         1,769        1,672
  Provision for credit losses                                 194               154           107          288  
                                                          -------           -------       -------      -------
  Net interest revenue after provision                                           
  for credit losses                                         1,481             1,883         1,662        1,384
                                                          -------           -------       -------      -------
NONINTEREST INCOME:                                             
  Financial service fees                                      480               580           529          519  
  Trust and agency fees                                       179               215           193          181  
  Trading profits and commissions                              16                18            26           18   
  Securities gains                                              7                14            32          116  
  Other income                                                260               208           165          186  
                                                          -------           -------       -------      -------
      Total noninterest income                                942             1,035           945        1,020
                                                          -------           -------       -------      -------
NONINTEREST EXPENSE:                                                 
  Salaries and employee benefits                              857             1,043           984          926  
  Occupancy and equipment expense                             248               317           312          317  
  Other real estate owned expense                               7                38            82          172  
  Acquisition and restructuring expense                                          21            85          
  Other expense                                               418               526           539          534  
                                                          -------           -------       -------      -------
      Total noninterest expense                             1,530             1,945         2,002        1,949
                                                          -------           -------       -------      -------
  Income before income taxes, extraordinary                                            
    item and cumulative effect of                                                       
    accounting change                                         893               973           605          455  
  Provision for income taxes                                  395               423           262          190  
                                                          -------           -------       -------      -------
  INCOME BEFORE EXTRAORDINARY                                            
   ITEM AND CUMULATIVE EFFECT OF                                                       
   ACCOUNTING CHANGE                                      $   498           $   550       $   343      $   265
                                                          =======           =======       =======      =======
PER COMMON SHARE:                                                     
  Income before extraordinary item and                                                      
    cumulative effect of accounting change:                                                  
      Primary                                             $  3.07           $  3.44       $  2.09      $  1.77 
      Fully diluted                                          3.00              3.37          2.05         1.73 
    Average number of common shares (in thousands):                                                  
      Primary                                             153,086           148,913       147,033      138,444
      Fully diluted                                       156,409           153,619       152,067      144,044


        See Notes to Unaudited Pro Forma Combined Financial Information
   3


 
                             UNAUDITED PRO FORMA COMBINED STATEMENT OF INCOME
                              FOR THE NINE MONTHS ENDED SEPTEMBER 30, 1995
  

(DOLLARS IN MILLIONS, EXCEPT PER SHARE AMOUNTS) BANK OF                    PRO FORMA     PRO FORMA       
                                                BOSTON      BAYBANKS(1)  ADJUSTMENTS(1)  COMBINED 
                                                ------      -----------  -------------   --------
                                                                                 
INTEREST INCOME:                                       
  Loans and lease financing, including fees     $ 2,394       $  466                      $ 2,860
   Securities                                       395          112                          507  
  Mortgages held for sale                            17            1                           18
  Federal funds sold and securities             
    purchased under agreements to resell            267            6                          273                          
  Deposits in other banks                           177            5                          182  
                                                -------       ------                      -------                           
    Total interest income                         3,250          590                        3,840
                                                -------       ------                      -------                            
INTEREST EXPENSE:                                               
  Deposits                                        1,179          169                        1,348
  Funds borrowed                                    656           42                          698                           
  Notes payable                                     116            3                          119
                                                -------       ------                      -------                                
    Total interest expense                        1,951          214                        2,165   
                                                -------       ------                      -------                   
  Net interest revenue                            1,299          376                        1,675                           
  Provision for credit losses                       175           19                          194
                                                -------       ------                      -------                              
  Net interest revenue after provision 
  for credit losses                               1,124          357                        1,481
                                                -------       ------                      -------  
NONINTEREST INCOME:                                                
  Financial service fees                            337          143                          480                           
  Trust and agency fees                             168           11                          179                           
  Trading profits and commissions                    14            2                           16                           
  Securities gains                                    7                                         7                           
  Other income                                      252            8                          260
                                                -------       ------                      -------                              
    Total noninterest income                        778          164                          942
                                                -------       ------                      -------                              
NONINTEREST EXPENSE:                                                          
  Salaries and employee benefits                    670          187                          857                           
  Occupancy and equipment expense                   180           68                          248                           
  Other real estate owned expense                     6            1                            7                           
  Other expense                                     312          106                          418
                                                -------       ------                      -------                              
    Total noninterest expense                     1,168          362                        1,530
                                                -------       ------                      -------                            
  Income before income taxes                        734          159                          893                           
  Provision for income taxes                        335           60                          395
                                                -------       ------        -------       -------                           
    NET INCOME                                  $   399       $   99                      $   498
                                                =======       ======        =======       =======                             
PER COMMON SHARE:                                                 
  Net income:                                                
      Primary                                   $  3.36       $ 5.11                      $  3.07   
      Fully diluted                                3.27         5.10                         3.00  
  Average number of common shares
   (in thousands):                                                
      Primary                                   110,188       19,499                      153,086
      Fully diluted                             113,458       19,523                      156,409                        


        See Notes to Unaudited Pro Forma Combined Financial Information
   4



                                  UNAUDITED PRO FORMA COMBINED STATEMENT OF INCOME
                                        FOR THE YEAR ENDED DECEMBER 31, 1994
                                 

(DOLLARS IN MILLIONS, EXCEPT PER SHARE AMOUNTS)          BANK OF                         PRO FORMA      PRO FORMA             
                                                         BOSTON          BAYBANKS(1)     ADJUSTMENTS(1) COMBINED    
                                                         ------          -----------     -----------    --------
                                                                                            
INTEREST INCOME:                                       
  Loans and lease financing, including fees              $ 2,606            $  508                      $ 3,114
  Securities                                                 355               140                          495   
  Mortgages held for sale                                     41                 2                           43
  Federal funds sold and securities                          
    purchased under agreements to resell                     600                 5                          605
  Deposits in other banks                                    116                 3                          119   
                                                         -------            ------                      -------
      Total interest income                                3,718               658                        4,376 
                                                         -------            ------                      -------
INTEREST EXPENSE:                                               
  Deposits                                                 1,148               153                        1,301 
  Funds borrowed                                             868                38                          906   
  Notes payable                                              130                 2                          132   
                                                         -------            ------                      -------
      Total interest expense                               2,146               193                        2,339 
                                                         -------            ------                      ------- 
  Net interest revenue                                     1,572               465                        2,037 
  Provision for credit losses                                130                24                          154   
                                                         -------            ------                      ------- 
  Net interest revenue after provision                       
  for credit losses                                        1,442               441                        1,883                 
                                                         -------            ------                      ------- 
NONINTEREST INCOME:                                                
  Financial service fees                                     396               184                          580   
  Trust and agency fees                                      201                14                          215   
  Trading profits and commissions                             16                 2                           18    
  Securities gains                                            14                                             14    
  Other income                                               201                 7                          208   
                                                         -------            ------                      ------- 
      Total noninterest income                               828               207                        1,035 
                                                         -------            ------                      ------- 
NONINTEREST EXPENSE:                                               
  Salaries and employee benefits                             813               230                        1,043 
  Occupancy and equipment expense                            231                86                          317   
  Other real estate owned expense                             22                16                           38    
  Acquisition and restructuring expense                       21                                             21    
  Other expense                                              392               134                          526   
                                                         -------            ------                      ------- 
      Total noninterest expense                            1,479               466                        1,945 
                                                         -------            ------                      ------- 
Income before income taxes, extraordinary                                                
  item and cumulative effect of                                                  
  of accounting change                                       791               182                          973   
  Provision for income taxes                                 349                74                          423   
                                                         -------            ------       -------        ------- 
INCOME BEFORE EXTRAORDINARY                                          
  ITEM AND CUMULATIVE EFFECT                                                 
  OF ACCOUNTING CHANGE                                   $   442            $  108                      $   550   
                                                         =======            ======       =======        =======
PER COMMON SHARE:                                                 
  Income before extraordinary item and                                                    
  cumulative effect of accounting change:                                                
      Primary                                            $  3.79            $ 5.65                      $  3.44
      Fully diluted                                         3.67              5.65                         3.37  
Average number of common shares (in thousands):                                                
      Primary                                            106,730            19,174                      148,913
      Fully diluted                                      111,427            19,177                      153,619


        See Notes to Unaudited Pro Forma Combined Financial Information
   5



                                UNAUDITED PRO FORMA COMBINED STATEMENT OF INCOME
                                     FOR THE YEAR ENDED DECEMBER 31, 1993
                                  

(DOLLARS IN MILLIONS, EXCEPT PER SHARE AMOUNTS)      BANK OF                    PRO FORMA      PRO FORMA             
                                                     BOSTON     BAYBANKS(1)    ADJUSTMENTS(1)  COMBINED              
                                                     ------     -----------    -----------     --------
                                                                                      
INTEREST INCOME:                                                  
  Loans and lease financing, including fees          $ 2,112       $  472                      $ 2,584     
  Securities                                             271           91                          362     
  Mortgages held for sale                                 76            9                           85                              
  Federal funds sold and securities                                                
    purchased under agreements to resell                 139            8                          147                              
  Deposits in other banks                                141           11                          152                             
                                                     -------       ------                      -------
      Total interest income                            2,739          591                        3,330
                                                     -------       ------                      -------                          
INTEREST EXPENSE:                                              
  Deposits                                             1,016          161                        1,177
  Funds borrowed                                         264            4                          268                          
  Notes payable                                          114            2                          116
                                                     -------       ------                      -------                             
      Total interest expense                           1,394          167                        1,561
                                                     -------       ------                      -------                          
  Net interest revenue                                 1,345          424                        1,769
  Provision for credit losses                             70           37                          107
                                                     -------       ------                      -------                            
  Net interest revenue after provision                                                    
  for credit losses                                    1,275          387                        1,662
                                                     -------       ------                      -------     
NONINTEREST INCOME:                                               
  Financial service fees                                 350          179                          529                          
  Trust and agency fees                                  178           15                          193                          
  Trading profits and commissions                         24            2                           26                          
  Securities gains                                        32                                        32                          
  Other income                                           162            3                          165
                                                     -------       ------                      -------                             
      Total noninterest income                           746          199                          945
                                                     -------       ------                      -------                             
NONINTEREST EXPENSE:                                              
  Salaries and employee benefits                         771          213                          984                          
  Occupancy  and equipment expense                       224           88                          312
  Other real estate owned expense                         44           38                           82                          
  Acquisition and restructuring expense                   85                                        85                          
  Other expense                                          407          132                          539
                                                     -------       ------                      -------                             
      Total noninterest expense                        1,531          471                        2,002
                                                     -------       ------                      -------                           
  Income before income taxes and                                 
    cumulative effect of accounting change               490          115                          605     
  Provision for income taxes                             215           47                          262
                                                     -------       ------      -------         -------                             
INCOME BEFORE CUMULATIVE                                            
  EFFECT OF ACCOUNTING CHANGE                        $   275       $   68                      $   343
                                                     =======       ======      =======         =======  
PER COMMON SHARE:                                                
  Income before cumulative effect                                                
    of accounting change:                                               
      Primary                                        $  2.28       $ 3.57                      $  2.09 
      Fully diluted                                     2.22         3.56                         2.05                       
  Average number of common shares (in thousands):                                               
      Primary                                        105,336       18,953                      147,033
      Fully diluted                                  110,258       19,004                      152,067     
                                                        

        See Notes to Unaudited Pro Forma Combined Financial Information
   6



                                  UNAUDITED PRO FORMA COMBINED STATEMENT OF INCOME
                                        FOR THE YEAR ENDED DECEMBER 31, 1992
                                 

(DOLLARS IN MILLIONS, EXCEPT PER SHARE AMOUNTS)          BANK OF                         PRO FORMA      PRO FORMA             
                                                         BOSTON          BAYBANKS(1)     ADJUSTMENTS(1) COMBINED    
                                                         ------          -----------     -----------    --------
                                                                                            
INTEREST INCOME:                                       
  Loans and lease financing, including fees              $ 2,291            $  532                      $ 2,823
  Securities                                                 391                94                          485   
  Mortgages held for sale                                     58                 9                           67     
  Federal funds sold and securities                          
    purchased under agreements to resell                      81                17                           98    
  Deposits in other banks                                    186                 5                          191    
                                                         -------            ------                      -------
      Total interest income                                3,007               657                        3,664 
                                                         -------            ------                      -------
INTEREST EXPENSE:                                               
  Deposits                                                 1,407               233                        1,640 
  Funds borrowed                                             271                 4                          275   
  Notes payable                                               74                 3                           77   
                                                         -------            ------                      -------
      Total interest expense                               1,752               240                        1,992 
                                                         -------            ------                      ------- 
  Net interest revenue                                     1,255               417                        1,672 
  Provision for credit losses                                181               107                          288    
                                                         -------            ------                      ------- 
  Net interest revenue after provision                       
  for credit losses                                        1,074               310                        1,384                 
                                                         -------            ------                      ------- 
NONINTEREST INCOME:                                                
  Financial service fees                                     355               164                          519   
  Trust and agency fees                                      166                15                          181   
  Trading profits and commissions                             16                 2                           18    
  Securities gains                                            39                77                          116       
  Other income                                               183                 3                          186   
                                                         -------            ------                      ------- 
      Total noninterest income                               759               261                        1,020 
                                                         -------            ------                      ------- 
NONINTEREST EXPENSE:                                               
  Salaries and employee benefits                             726               200                          926
  Occupancy and equipment expense                            227                90                          317   
  Other real estate owned expense                            113                59                          172    
  Other expense                                              408               126                          534   
                                                         -------            ------                      ------- 
      Total noninterest expense                            1,474               475                        1,949 
                                                         -------            ------                      ------- 
Income before income taxes and 
  extraordinary item                                         359                96                          455   
Provision for income taxes                                   153                37                          190   
                                                         -------            ------        -------       ------- 
INCOME BEFORE EXTRAORDINARY                                          
  ITEM                                                   $   206            $   59                      $   265   
                                                         =======            ======        =======       =======
PER COMMON SHARE:                                                 
  Income before extraordinary 
  item: 
      Primary                                            $  1.82            $ 3.57                      $  1.77
      Fully diluted                                         1.78              3.54                         1.73  
Average number of common shares (in thousands):                                                
      Primary                                            101,977            16,576                      138,444
      Fully diluted                                      107,157            16,767                      144,044

                                                  
        See Notes to Unaudited Pro Forma Combined Financial Information
   7
  


     NOTES TO UNAUDITED PRO FORMA COMBINED FINANCIAL INFORMATION
 
(1)  Certain historical data of BayBanks have been reclassified on a pro forma 
     basis to conform to Bank of Boston's classifications.  Transactions
     between Bank of Boston and BayBanks are not material in relation to the 
     pro forma combined financial statements, and have not been eliminated from
     the pro forma combined amounts.
  
(2)  Reflects preliminary estimated acquisition and restructuring costs of 
     $140 million ($83 million net of taxes).  Such costs include estimated
     investment banking and other professional fees, stock issuance costs and
     other expenses associated with the proposed merger and estimated
     facilities and operations consolidation and involuntary termination  costs
     associated with expected reorganizations following the proposed merger.
  
(3)  Reflects the conversion of BayBanks Common Stock into Bank of Boston 
     Common Stock.  Pursuant to the agreement with BayBanks, each outstanding
     share (19,622,393 shares at September 30, 1995) of BayBanks Common
     Stock will be converted into 2.2 shares of Bank of Boston Common Stock,
     subject to adjustment in certain circumstances. 
  
(4)  In connection with its proposed merger with BayBanks, Bank of Boston will 
     file a Registration Statement on Form S-4 with the Securities and
     Exchange Commission (the "Commission") registering Bank of Boston Common
     Stock to be issued in connection therewith.  This registration statement,
     which will be subject to review and comment by the Staff of the
     Commission, will include pro forma financial information for Bank of
     Boston and BayBanks.  Such pro forma financial information may differ from
     the pro forma financial information included herein.