<PAGE>                                        
                          QUARTERLY REPORT ON FORM 10-Q
                     U.S. SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON D.C. 20549
                            _________________________
                                        
(Mark One)
[ X ] QUARTERLY REPORT UNDER SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE  ACT
      OF 1934
      For the quarterly period ended September 27, 1998

                                       or

[   ] TRANSITION  REPORT  PURSUANT  TO SECTION 13 OR  15(d)  OF  THE  SECURITIES
      EXCHANGE ACT OF 1934
      For the transition period from _____________to_____________


                         Commission File Number: 1-12432


                      AMERICAN POWER CONVERSION CORPORATION
             (Exact name of Registrant as specified in its charter)
                                        
                                        
                  MASSACHUSETTS                     04-2722013
        (State or other jurisdiction of          (I.R.S. employer
         incorporation or organization)         identification no.)
                                        
                                        
             132 FAIRGROUNDS ROAD, WEST KINGSTON, RHODE ISLAND 02892
                                  401-789-5735
          (Address and telephone number of principal executive offices)


Indicate  by check mark whether the Registrant (1) has filed all reports  to  be
filed by section 13 or 15 (d) of the Securities Exchange Act of 1934 during  the
preceding 12 months (or for such shorter period that the Registrant was required
to  file such reports), and (2) has been subject to such filing requirements for
the past 90 days.

                             YES  [ X ]    NO  [   ]

                                        

  Registrant's Common Stock outstanding, $.01 par value, at November 6, 1998 -
                                95,715,000 shares

                                        1
<PAGE>
                                                                       FORM 10-Q
                                                              September 27, 1998


             AMERICAN POWER CONVERSION CORPORATION AND SUBSIDIARIES
                                        
                                      INDEX


                                                                   Page No.

Part I - Financial Information:
     
     Item 1. Consolidated Condensed Financial Statements:
             Consolidated Condensed Balance Sheets -
             September 27, 1998 (Unaudited) and December 31, 1997   3 - 4
           
             Consolidated Condensed Statements of Income -
             Three Months and Nine Months Ended
             September 27, 1998 and September 28, 1997 (Unaudited)    5
           
             Consolidated Condensed Statements of Cash Flows -
             Three Months and Nine Months Ended
             September 27, 1998 and September 28, 1997 (Unaudited)    6
           
             Notes to Consolidated Condensed Financial Statements
             (Unaudited)                                            7 - 8
     
     Item 2. Management's Discussion and Analysis of Financial
             Condition and Results of Operations                    8 - 13
           
Part II - Other Information:

     Item 1. Legal Proceedings                                       14
     
     Item 6. Exhibits and Reports on Form 8-K                        14
     
Signatures                                                           15

                                        2
<PAGE>
                                                                       FORM 10-Q
                                                              September 27, 1998
PART I - CONSOLIDATED CONDENSED FINANCIAL STATEMENTS

ITEM 1 - FINANCIAL STATEMENTS
<TABLE>

             AMERICAN POWER CONVERSION CORPORATION AND SUBSIDIARIES
                      CONSOLIDATED CONDENSED BALANCE SHEETS
                                 (In thousands)
                                        
                                     ASSETS
<CAPTION>
                                                        September 27,        December 31,
                                                                1998                1997
                                                                     (Unaudited)               
<S>                                                         <C>                 <C>
Current assets:                                                                  
Cash and cash equivalents                                   $208,857            $270,134
Accounts receivable,                                                             
 less allowance for doubtful accounts of                                         
 $16,630 in 1998 and $12,230 in 1997                         198,841             131,115
Inventories:                                                                     
 Raw materials                                               116,398              61,430
 Work-in-process and finished goods                          106,524              42,741
Total inventories                                            222,922             104,171
                                                                                 
Prepaid expenses and other current assets                     20,042              13,305
                                                                                 
Deferred income taxes                                         26,200              21,571
                                                                                 
Total current assets                                         676,862             540,296
                                                                                 
Property, plant, and equipment:                                                  
 Land, buildings and improvements                             50,804              31,143
 Machinery and equipment                                     119,837              80,091
 Office equipment, furniture, and fixtures                    42,318              31,431
 Purchased software                                           11,082               9,584
                                                             224,041             152,249
Less accumulated depreciation and amortization                81,821              52,631
Net property, plant, and equipment                           142,220              99,618
                                                                                 
Goodwill and other intangibles                                38,821                   -
                                                                                 
Other assets                                                   3,650               1,376
                                                                                 
                                                                                 
Total assets                                                $861,553            $641,290
                                        
</TABLE>
                                        
                                        
     See accompanying notes to consolidated condensed financial statements.

                                        3
<PAGE>
                                                                       FORM 10-Q
                                                              September 27, 1998

<TABLE>
             AMERICAN POWER CONVERSION CORPORATION AND SUBSIDIARIES
                CONSOLIDATED CONDENSED BALANCE SHEETS (CONTINUED)
                                 (In thousands)
                                        
                      LIABILITIES AND SHAREHOLDERS' EQUITY
<CAPTION>
                                                        September 27,        December 31,
                                                                1998                1997
                                                                   (Unaudited)               
<S>                                                          <C>                 <C>
Current liabilities:                                                             
Short term debt                                              $15,045             $     -
Accounts payable                                             106,046              37,068
Accrued expenses                                              26,961              16,334
Accrued compensation                                          18,610              16,476
Accrued sales and marketing programs                          16,173              15,965
Accrued retirement contributions                               8,417               7,446
Income taxes payable                                          31,280              20,241
                                                                                 
Total current liabilities                                    222,532             113,530
                                                                                 
Deferred tax liability                                         7,992               6,006
                                                                                 
Total liabilities                                            230,524             119,536
                                                                                 
Minority interest                                              3,253                   -
                                                                                 
Shareholders' equity:                                                            
Common stock, $.01 par value;                                                    
 authorized 200,000 shares; issued 95,773                                        
 shares in 1998 and 95,383 shares in 1997                        958                 954
Additional paid-in capital                                    61,717              55,626
Retained earnings                                            566,841             466,725
Treasury stock, 125 shares, at cost                          (1,551)             (1,551)
Currency translation adjustment                                (189)                   -
                                                                                 
Total shareholders' equity                                   627,776             521,754
                                                                                 
Total liabilities and shareholders' equity                  $861,553            $641,290
                                        
</TABLE>

                                        
     See accompanying notes to consolidated condensed financial statements.

                                        4
<PAGE>
                                                                       FORM 10-Q
                                                              September 27, 1998

<TABLE>
             AMERICAN POWER CONVERSION CORPORATION AND SUBSIDIARIES
                   CONSOLIDATED CONDENSED STATEMENTS OF INCOME
                    (In thousands except earnings per share)
<CAPTION>
                                                    Nine months ended         Three months ended
                                                  September    September    September    September
                                                         27,          28,          27,          28,
                                                       1998         1997         1998         1997
                                                                       (Unaudited)         
                                                                                           
<S>                                                <C>          <C>          <C>          <C>
Net sales                                          $806,898     $621,653     $327,370     $246,044
                                                                                           
Cost of goods sold                                  446,385      340,482      183,087      132,471
                                                                                           
Gross profit                                        360,513      281,171      144,283      113,573
                                                                                           
Operating expenses:                                                                        
Marketing, selling, general and administrative      189,750      144,987       70,841       55,705
Research and development                             24,658       15,782        7,962        6,186
Acquired research and development                     7,554            -          167            -
                                                                                           
Total operating expenses                            221,962      160,769       78,970       61,891
                                                                                           
Operating income                                    138,551      120,402       65,313       51,682
                                                                                           
Other income, net                                     9,128        2,750        2,149        2,002
                                                                                           
Earnings before income taxes                        147,679      123,152       67,462       53,684
                                                                                           
Income taxes                                         47,340       38,793       20,621       16,911
                                                                                           
Earnings before minority interest                   100,339       84,359       46,841       36,773
                                                                                           
Minority interest, net                                  223            -          223            -
                                                                                           
Net income                                         $100,116      $84,359      $46,618      $36,773
                                                                                           
Basic earnings per share                            $  1.05       $  .89       $  .49      $   .39
                                                                                           
Basic weighted average shares outstanding            95,412       94,915       95,537       95,154
                                                                                           
Diluted earnings per share                          $  1.04       $  .88       $  .48      $   .38
                                                                                           
Diluted weighted average shares outstanding          96,647       96,125       96,861       96,495
                                        
</TABLE>
                                        
                                        
     See accompanying notes to consolidated condensed financial statements.

                                        5
<PAGE>
                                                                       FORM 10-Q
                                                              September 27, 1998
                                                                                
<TABLE>
             AMERICAN POWER CONVERSION CORPORATION AND SUBSIDIARIES
                 CONSOLIDATED CONDENSED STATEMENTS OF CASH FLOWS
                                 (In thousands)
                                        
<CAPTION>
                                                     Nine months ended         Three months ended
                                                  September    September    September    September
                                                         27,          28,          27,          28,
                                                       1998         1997         1998         1997
                                                                       (Unaudited)              
<S>                                                <C>           <C>          <C>          <C>
Cash flows from operating activities                                         
Net income                                         $100,116      $84,359      $46,618      $36,773
Adjustments to reconcile net income to net cash                                            
 provided by operating activities:                                                         
Depreciation and amortization                        18,134       13,335        6,391        4,918
Provision for doubtful accounts                       6,295        3,455        3,697        1,327
Deferred income taxes                                (4,479)      (4,327)      (1,247)       2,884
Acquired research and development                     7,554            -          167            -
Changes in operating assets and liabilities                                                
 excluding effects of acquisitions:
  Accounts receivable                               (54,508)     (33,810)     (19,179)     (23,085)
  Inventories                                       (99,567)      11,958      (23,145)      40,749
  Prepaid expenses and other current assets          (6,392)      (1,025)      (2,273)         837
  Other assets                                       (1,549)         507       (1,234)         (18)
  Accounts payable                                    54,406      (7,678)       4,476       (3,784)
  Accrued expenses                                     8,609       9,834        8,987        9,616
  Income taxes payable                                10,885       2,847        8,482        6,197
Other, net                                               (38)          -          (38)           -
Net cash provided by operating activities             39,466      79,455       31,702       76,414
                                                                                           
Cash flows from investing activities                                                       
Capital expenditures, net of capital grants          (43,321)    (26,570)     (19,147)      (8,057)
Acquisitions                                         (53,714)        101       (1,185)           -
Net cash used in investing activities                (97,035)    (26,469)     (20,332)      (8,057)
                                                                                           
Cash flows from financing activities                                                       
Repayment of short term debt                          (9,803)          -       (9,803)           -
Proceeds from issuances of common stock                6,095       5,681        3,980          739
Net cash provided by (used in) financing activities   (3,708)      5,681       (5,823)         739
                                                                                           
Net change in cash and cash equivalents              (61,277)     58,667        5,547       69,096
Cash and cash equivalents at beginning of period     270,134     153,234      203,310      142,805
Cash and cash equivalents at end of period          $208,857    $211,901     $208,857     $211,901
                                        
Supplemental cash flow disclosures                                                         
Cash paid for income taxes (net of refunds)          $36,301     $34,260      $12,139      $ 8,716
Details of acquisitions:                                                                   
 Fair value of assets                               $105,517      $    -        $ 973        $   -
 Liabilities and minority interest                   (49,843)          -          212            -
 Cash paid                                            55,674           -        1,185            -
 Cash acquired                                        (1,960)       (101)           -            -
 Acquisitions                                        $53,714       $(101)      $1,185        $   -
                                        
</TABLE>
                                        
                                        
     See accompanying notes to consolidated condensed financial statements.

                                        6
<PAGE>
                                                                       FORM 10-Q
                                                              September 27, 1998



             AMERICAN POWER CONVERSION CORPORATION AND SUBSIDIARIES
              NOTES TO CONSOLIDATED CONDENSED FINANCIAL STATEMENTS
                                   (Unaudited)



1.   Management Representation

In  the  opinion  of  management, the accompanying unaudited  interim  financial
statements  contain  all  adjustments  (consisting  of  only  normal   recurring
accruals) necessary to present fairly the financial position and the results  of
operations  for the interim periods.  The results of operations for the  interim
periods  are not necessarily indicative of results to be expected for  the  full
year.

2.   Principles of Consolidation

The  consolidated  financial statements include the accounts of  American  Power
Conversion  Corporation and all of its wholly- and majority-owned  subsidiaries.
All intercompany accounts and transactions are eliminated in consolidation.

Early  in  the  second quarter of 1998, the Company entered  into  a  definitive
agreement  with the principal management shareholders of Silcon A/S  to  acquire
stock of Silcon, a Denmark-based manufacturer of three-phase UPSs up to 480 kVA,
and  the Company commenced a tender offer for Silcon shares.  In June 1998,  the
initial   tender   offer  and  purchase  of  stock  from  principal   management
shareholders was completed enabling the Company to operate Silcon as a majority-
owned  subsidiary.  The acquisition has been accounted for as  a  purchase  and,
accordingly,  Silcon's  results  of operations are  included  in  the  Company's
consolidated financial statements from the date of acquisition.

3.   Per Share Data

Basic  earnings  per share is computed by dividing net income  by  the  weighted
average number of common shares outstanding during the period.  Diluted earnings
per  share is computed by dividing net income by the weighted average number  of
common  shares  and  dilutive  potential common shares  outstanding  during  the
period.  Under the treasury stock method, the unexercised options are assumed to
be  exercised  at  the beginning of the period or at issuance,  if  later.   The
assumed  proceeds are then used to purchase common shares at the average  market
price  during  the  period.   Dilutive potential common  shares  outstanding  at
September 27, 1998 and September 28, 1997 were approximately 1.3 million and 1.3
million, respectively.

Potential  common shares for which inclusion would have the effect of increasing
diluted   earnings  per  share  (i.e.,  antidilutive)  are  excluded  from   the
computation.  Antidilutive potential common shares outstanding at September  27,
1998  and  September 28, 1997 were approximately 2.2 million  and  18  thousand,
respectively.

4.   Shareholders' Equity

Changes in paid-in capital for the periods presented represent the issuances  of
common stock resulting from the exercise of employee stock options.

                                        7
<PAGE>
5.   Comprehensive Income

The components of comprehensive income, net of tax, are as follows:
<TABLE>
<CAPTION>
                                                    Nine months ended         Three months ended
                                                  September   September    September    September
                                                         27,         28,          27,          28,
                                                       1998        1997         1998         1997
<S>                                                <C>          <C>          <C>          <C>   
Net income                                         $100,116     $84,359      $46,618      $36,773
                                                                                           
Other comprehensive income, net of tax:                                                    
  Foreign currency translation adjustment              (189)          -         (189)           -
Other comprehensive income                             (189)          -         (189)           -
                                                                                           
Comprehensive income                                $99,927     $84,359      $46,429      $36,773

</TABLE>

ITEM 2.   MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
     CONDITION AND RESULTS OF OPERATIONS

RESULTS OF OPERATIONS:

Revenues

Net  sales  were  $327.4 million for the third quarter of 1998, an  increase  of
33.1% compared to $246.0 million for the same period in 1997.  Net sales for the
first  nine  months  of 1998 were $806.9 million compared to $621.7  million  in
1997,  an increase of 29.8%.  The increase was attributable to continued  strong
demand for the Company's uninterruptible power supply (UPS) and surge protection
products.  Third quarter and nine month year-to-date net sales growth was strong
worldwide  with the Americas (North and Latin America) growing 32.1% and  30.0%,
respectively,  EMEA (Europe, Middle East and Africa) growing  43.5%  and  39.8%,
respectively,  and the Asia Pacific region growing 16.8% and 9.6%, respectively,
despite  the  economic  downturn  in  that  region.   International  net   sales
(excluding Canada) comprised 37% of total net sales in each of the third quarter
and first nine month periods of 1998 and 1997, respectively.

Cost of Goods Sold

Cost of goods sold was $183.1 million or 55.9% of net sales in the third quarter
of  1998 compared to $132.5 million or 53.8% in the third quarter of 1997.  Cost
of  goods sold was $446.4 million or 55.3% of net sales in the first nine months
of  1998 compared to $340.5 million or 54.8% in the same period of 1997.   Gross
margins  declined by approximately 210 basis points and 50 basis  points  during
the  third  quarter  and  first  nine months of  1998,  respectively,  over  the
comparable  periods in 1997.  Substantially all of the gross margin erosion  was
product  mix related as the Company's high end UPS business now accounts  for  a
larger  percentage  of  revenue, combined with seasonally  strong  desktop  unit
volume  growth  of  Back-UPSr products that were price  reduced  in  the  fourth
quarter  of  1997.  Total inventory reserves at September 27,  1998  were  $23.5
million  compared to $19.3 million at December 31, 1997.  The Company's  reserve
estimate  methodology involves quantifying the total inventory  position  having
potential loss exposure, reduced by an amount reasonably forecasted to be  sold,
and adjusting its interim reserve provisioning to cover the net loss exposure.

Operating Expenses

Operating  expenses  include  marketing,  selling,  general  and  administrative
(SG&A), and research and development (R&D) expenses.

                                        8
<PAGE>
SG&A expenses were $70.8 million or 21.6 % of net sales for the third quarter of
1998  compared to $55.7 million or 22.6% of net sales for the third  quarter  of
1997.   SG&A  expenses were $189.8 million or 23.5% of net sales for  the  first
nine  months  of 1998 compared to $145.0 million or 23.3% of net sales  for  the
first nine months of 1997. The aggregate dollars of SG&A expenses have increased
over  last  year  due primarily to costs associated with increased  staffing  of
sales  and  administrative  positions  both  domestically  and  internationally.
However, the slight decrease as a percentage of sales from third quarter 1997 to
third quarter 1998 is attributable to certain fixed SG&A expenses spread over  a
higher  revenue  base,  as  well  as the Company's  focused  efforts  to  manage
spending.  The allowance for doubtful accounts at September 27, 1998 was 7.7% of
accounts  receivable,  compared  to 8.5% at  December  31,  1997.   The  Company
continues to experience strong collection performance.

Excluding  1998  charges  of $7.6 million for acquired  R&D  (see  "Acquisition"
below), R&D expenses were $8.0 million or 2.4% of net sales and $6.2 million  or
2.5% of net sales for the third quarters of 1998 and 1997, respectively, and R&D
expenses  were $24.7 million or 3.1% of net sales and $15.8 million or  2.5%  of
net  sales for the first nine month periods of 1998 and 1997, respectively.  The
increased  R&D  spending primarily reflects increased numbers  of  software  and
hardware  engineers  and  costs  associated with  new  product  development  and
engineering  support.   Although the aggregate  dollars  of  R&D  expenses  have
increased  as a result of continued product and process development, the  slight
decrease as a percentage of sales from third quarter 1997 to third quarter  1998
is attributable to certain fixed R&D expenses spread over a higher revenue base.

Other Income, Net and Income Taxes

Other  income  is  comprised  principally of interest  income,  which  increased
substantially  from  1997 to 1998 due to higher average cash balances  available
for investment during 1998.

Excluding 1998 non-tax deductible charges of $7.6 million for acquired R&D  (see
"Acquisition"   below),   the  Company's  effective  income   tax   rates   were
approximately  30.5%  and 31.5% for the quarters ended September  27,  1998  and
September  28, 1997, respectively.  The decrease from last year is  due  to  the
expected  tax  savings  from  an increasing portion of  taxable  earnings  being
generated  from  the  Company's  operations in  Ireland,  a  jurisdiction  which
currently  has  a  lower income tax rate for manufacturing  companies  than  the
present U.S. statutory income tax rate.

LIQUIDITY AND CAPITAL RESOURCES

Working  capital  at  September 27, 1998 was $454.3 million compared  to  $426.8
million  at December 31, 1997.  The Company's cash position decreased to  $208.9
million  at  September  27,  1998  from $270.1 million  at  December  31,  1997,
primarily due to the cash purchase of approximately 77% of the share capital  of
Silcon A/S (see "Acquisition" below).

Worldwide  inventories were $222.9 million at September  27,  1998  compared  to
$104.2  million  at December 31, 1997.  Inventories increased during  the  first
nine months of 1998 due to anticipation of increased demand patterns during  the
second  half  of  the year which result from typical seasonal factors,  combined
with  $19 million of inventory purchased in the Silcon acquisition.  During  the
third  quarter of 1998, inventories grew 11.6% over second quarter 1998  levels,
compared  to  a 25.6% growth rate for third quarter 1998 net sales  over  second
quarter  1998.  Inventory levels were 68% as a percentage of quarterly sales  in
the third quarter of 1998, down from 77% in the second quarter of 1998.

At  September  27,  1998,  the  Company had $50  million  available  for  future
borrowings  under  an unsecured line of credit agreement at a floating  interest
rate  equal  to  the bank's cost of funds rate plus .625% and an additional  $15
million  under  an unsecured line of credit agreement with a second  bank  at  a
similar interest rate.  No borrowings were outstanding under these facilities at
September  27,  1998.   In  connection  with  the  acquisition  of  Silcon  (see
"Acquisition"  below), the Company acquired $24.8 million in  bank  indebtedness
with  interest rates ranging from 4% to 8%.  The Company repaid $9.8 million  of
this  indebtedness  during  the third quarter  of  1998.   The  Company  had  no

                                        9
<PAGE>
significant  financial  commitments, other than those  required  in  the  normal
course of business, at September 27, 1998.

Capital  investment  for  the first nine months of 1998 consisted  primarily  of
manufacturing and office equipment, and buildings and improvements.  The  nature
and level of capital spending was made to improve manufacturing capabilities and
to   support  the  increased  marketing,  selling,  and  administrative  efforts
necessitated  by the Company's growth.  Net capital expenditures  were  financed
from available operating cash.  The Company had no material capital commitments,
other  than  those required in the normal course of business, at  September  27,
1998.

The  Company has agreements with the Industrial Development Authority of Ireland
("IDA")  under  which the Company receives grant monies for costs  incurred  for
machinery,  equipment, and building improvements for its  Galway  and  Castlebar
facilities equal to 40% and 60%, respectively, of such costs up to a maximum  of
$13.1 million and $1.3 million, respectively.  Such grant monies are subject  to
the  Company  meeting  certain employment goals and  maintaining  operations  in
Ireland  until  termination of the respective agreements.  The total  cumulative
amounts  of  capital grant claims submitted and received through  September  27,
1998  for the Galway facility were approximately $12.6 million and $8.9 million,
respectively.   The  total cumulative amount of capital grant  claims  submitted
through  September  27, 1998 for the Castlebar facility  was  $1.2  million;  no
capital  grant  claims  had  been received for the  Castlebar  facility.   Under
separate  agreements with the IDA, the Company receives direct reimbursement  of
training  costs  at its Galway and Castlebar facilities for  up  to  $3,000  and
$12,500, respectively, per new employee hired.  The total cumulative amounts  of
training grant claims submitted and received through September 27, 1998 for  the
Galway  facility were approximately $1.8 million and $1.3 million, respectively.
The total cumulative amount of training grant claims submitted through September
27,  1998 for the Castlebar facility was approximately $0.9 million; no training
grant claims had been received for the Castlebar facility.

During the first quarter of 1998, the Company began establishing a manufacturing
operation  in  China.  The Company is leasing a 50,000 square foot  facility  in
Suzhou  and  began manufacturing selected products at this facility  during  the
third  quarter  of 1998.  Capital expenditures for the China expansion  will  be
financed  from  operating cash.  In August 1998, the Company purchased  a  third
manufacturing  facility in the Philippines for approximately $750,000,  financed
from   operating   cash.   The  Company  continues  to  evaluate   international
manufacturing expansion including additional locations in the Far East and South
America.

Management  believes that current internal cash flows, together  with  available
cash,  available credit facilities or, if needed, the proceeds from the sale  of
additional  equity, will be sufficient to support anticipated  capital  spending
and other working capital requirements for the foreseeable future.

Acquisition

Early  in  the  second quarter of 1998, the Company entered  into  a  definitive
agreement  with the principal management shareholders of Silcon A/S  to  acquire
stock of Silcon, a Denmark-based manufacturer of three-phase UPSs up to 480 kVA,
and  the Company commenced a tender offer for Silcon shares.  In June 1998,  the
initial   tender   offer  and  purchase  of  stock  from  principal   management
shareholders was completed enabling the Company to operate Silcon as a majority-
owned  subsidiary.  During the third quarter of 1998, the Company increased  its
ownership  percentage to 77%.  The Company's cash outlays of  $56  million  were
financed from operating cash.

The  purchase price was allocated to the net assets acquired and to acquired in-
process  research  and development (acquired R&D).  Acquired  R&D  includes  the
value  of  products in the development stage and not considered to have  reached
technological  feasibility.   In accordance with  applicable  accounting  rules,
acquired  R&D  is  required to be expensed.  Accordingly, $7.4  million  of  the
acquisition cost was expensed in the second quarter of 1998.  An additional  $.2
million  was expensed in the third quarter of 1998 consistent with the Company's
increased ownership percentage.  The remaining purchase price exceeded the  fair
value of the tangible net assets acquired by approximately $39 million, which is
being  amortized on a straight-line basis over periods ranging from 10-20 years.
The  acquisition has been accounted for as a purchase and, accordingly, Silcon's
results  of  operations  are  included in the Company's  consolidated  financial
statements from the date of acquisition.

                                       10
<PAGE>
Foreign Currency Activity

Financial statements for the Company's international subsidiaries for which  the
U.S.  dollar  is the functional currency are remeasured into U.S. dollars  using
current  rates  of exchange for monetary assets and liabilities  and  historical
rates  of  exchange for nonmonetary assets.  Gains and losses from remeasurement
are included in other income, net.

The Company invoices its customers in Japan, Great Britain, Germany, and France,
in  their  respective  local currencies.  At September 27,  1998  the  Company's
unhedged foreign currency accounts receivable, by currency, were as follows:
   (In thousands)          Foreign Currency        U.S. Dollars
   Japanese Yen                   1,619,000              11,320
   British Pounds                     4,201               7,132
   German Marks                      19,723              11,810
   French Francs                     36,146               6,443

Total  gross accounts receivable at September 27, 1998 was approximately  $215.5
million.   The  Company  had non-trade receivables of 4.1 million  Irish  Pounds
(approximately  US$6.2 million), as well as Irish Pound denominated  liabilities
of 4.4 million (approximately US$6.5 million).  The Company also had liabilities
denominated  in various European currencies of US$14.7 million, as well  as  Yen
denominated liabilities of approximately US$1.9 million.

The  Company  continually reviews its foreign exchange  exposure  and  considers
various  risk  management techniques including the netting of  foreign  currency
receipts  and  disbursements, rate protection agreements with  customers/vendors
and derivatives arrangements, including foreign exchange contracts.  The Company
presently   does   not  utilize  rate  protection  agreements   or   derivatives
arrangements.

Recently Issued Accounting Standards

During  1997,  the  Financial Accounting Standards  Board  issued  Statement  of
Financial  Accounting  Standards  No. 131,  Disclosures  about  Segments  of  an
Enterprise  and Related Information, which establishes standards  for  reporting
information about operating segments in annual and interim financial  statements
issued  to shareholders.  This Statement also establishes standards for  related
disclosures about products and services, geographic areas, and major  customers.
The  Company  will  adopt this Statement at December 31, 1998 and  is  currently
studying its provisions.

The  Financial Accounting Standards Board recently issued Statement of Financial
Accounting Standards No. 133, Accounting for Derivative Instruments and  Hedging
Activities, which establishes accounting and reporting standards for  derivative
instruments,  including  certain  derivative  instruments  embedded   in   other
contracts (collectively referred to as derivatives), and for hedging activities.
This  Statement  is effective for all fiscal quarters of fiscal years  beginning
after  June 15, 1999.  The adoption of this Statement is not expected to have  a
material impact on the Company's financial position or results of operations.

The AICPA Accounting Standards Executive Committee recently issued Statement  of
Position  ("SOP") 98-1, Accounting for the Costs of Computer Software  Developed
or  Obtained for Internal Use.  This SOP requires that certain costs related  to
the  development  or  purchase  of  internal-use  software  be  capitalized  and
amortized  over the estimated useful life of the software, and is effective  for
fiscal  years  beginning after December 15, 1998.  The SOP  also  requires  that
costs    related    to    the    preliminary    project    stage    and     post
implementation/operations stage in an internal-use computer software development
project  be  expensed as incurred.  The adoption of this SOP is not expected  to
have  a  material  impact  on the Company's financial  position  or  results  of
operations.

The AICPA Accounting Standards Executive Committee recently issued Statement  of
Position ("SOP") 98-5, Reporting on the Costs of Start-Up Activities.  This  SOP
requires  that costs incurred during start-up activities, including organization
costs,  be  expensed  as incurred, and is effective for fiscal  years  beginning

                                       11
<PAGE>
after December 15, 1998.  The adoption of this SOP is expected to have no impact
on the Company's financial position or results of operations.

Year 2000 Readiness Disclosure Statement

Many computer systems were not designed to handle any dates beyond the year 1999
and,  therefore,  many  companies  will be required  to  modify  their  computer
hardware  and  software  prior  to  the year  2000  in  order  to  remain  fully
operational.   During 1998, the Company commenced a year 2000 readiness  program
to  assess  the  impact of the year 2000 issue on the Company's  operations  and
address  necessary remediation.  A year 2000 program director reporting directly
to senior management has been assigned to this project, which includes:

Assessment  of  the  Company's products for year 2000 compliance.   All  of  the
Company's  hardware  products and accessories are year 2000  compliant,  meaning
that they have been tested to verify that where date fields are processed, dates
are  calculated  and  displayed accurately, and that scheduled  events  such  as
shutdowns,  self-tests,  and run-time calibrations, and  also  the  handling  of
unscheduled events, such as power failures, are unaffected by the millenium  and
century  change;  provided that all other third party products (e.g.,  software,
firmware, operating systems, and hardware) properly exchange date data with  the
Company  product  and  provided  also that the  Company  products  are  used  in
accordance with the product documentation.  In addition, the Company's year 2000
compliant products recognize the year 2000 as a leap year.  The Company has also
tested   its   software  products  and  determined  that  these   products   are
substantially  year  2000  compliant, and the Company  intends  to  resolve  any
remaining  year  2000  issues  before the arrival of  year  2000.   Periodically
updated  information about the Company's software products is available  at  the
Company's  Year 2000 Readiness Disclosure Web site (www.APCC.com).   Information
on  this  site  is provided to the Company's customers for the sole  purpose  of
assisting in planning for transition to the year 2000.  Such information is  the
most  currently available concerning the behavior of the Company's  products  in
the  next  century and is provided "as is" without warranty  of  any  kind.   In
addition,  to  the  extent  the Company's hardware  and  software  products  are
combined  with the hardware and software products of other companies, there  can
be  no  assurance that users of the Company's products will not experience  year
2000  problems  as  a  result of the combination of the Company's  hardware  and
software  products with non-compliant products of other companies.  The  Company
currently  does  not anticipate material expenditures to remedy  any  year  2000
issues with its products and services.

Assessment of the Company's information technology ("IT") and non-IT systems for
year 2000 compliance.  The Company is currently in the process of evaluating its
IT  systems  for compliance.  The Company's Oracle manufacturing  and  financial
information  systems  were implemented during 1998.  The  Company  is  currently
evaluating the year 2000 compliance of these systems in accordance with Oracle's
recommendations.   The  Company has installed the most recent  software  patches
available  from Oracle and expects its initial testing of these  patches  to  be
complete by the end of 1998.  The Company does not consider the cost of the  new
hardware and software for the Oracle implementations to be related to year  2000
readiness  as  these  system replacements were already planned  to  satisfy  the
demands of expansion of its worldwide operations and were not accelerated due to
year  2000  issues.  The Company is also currently in the process of  evaluating
its  non-IT  systems for compliance.  Additionally, the Company  utilizes  other
third  party  software and equipment to distribute its products as  well  as  to
operate  other aspects of its business.  The Company is reviewing such  software
and  equipment.  There can be no assurance that such software and  equipment  is
year  2000  compliant, that non-compliant software and equipment  will  be  made
compliant  on  a  timely  basis,  or that any such  non-compliant  software  and
equipment would not have a material adverse effect on the Company's systems  and
operations.

Evaluation  of third parties with which the Company has a material relationship,
including  key  suppliers,  service  providers,  and  strategic  partners.   The
Company's  year 2000 readiness program includes identifying these third  parties
and  determining, based on receipt of written verification, review  of  publicly
available  financial  statement disclosures, and other means,  that  such  third
parties  are either in compliance or expect to be in compliance prior to January
1,  2000.   The  Company is currently in the process of communicating  with  its
significant  vendors, service providers, and certain strategic  partners.   Many
enterprises,  including the Company's present and potential  customers,  may  be
devoting  a  substantial  portion  of  their  information  systems  spending  to

                                       12
<PAGE>
resolving  year  2000 issues, which may result in their spending being  diverted
from applications such as the Company's products, over the next two years.

Development of contingency plans.  The Company is currently not in a position to
determine what would be its most reasonably likely worst case year 2000 scenario
or  any plan for handling such scenario.  To date, the Company has not completed
a formal contingency plan for non-compliance, however to the extent that further
evaluation  of its products, its IT and non-IT systems, or information  obtained
from  the third parties with which it has a material relationship suggests  that
there  is  a  significant  risk, contingency plans will  be  implemented.   Such
contingency  plans may include the development of alternative  sources  for  the
product or service provided by any non-compliant vendor.

It is the Company's policy to expense as incurred all costs associated with year
2000  readiness.  To date, the Company has not identified a separate budget  for
year  2000 issues.  No IT projects have been deferred due to year 2000  efforts.
Although the Company is not yet able to estimate its total incremental cost  for
year 2000 issues, based on its preliminary review to date, the Company does  not
believe  that the costs of year 2000 issues will have a material adverse  effect
on  the Company's business, operating results, or financial condition.  Although
the  Company  is  taking measures to address the impact, if any,  of  year  2000
issues,  it  cannot  predict the outcome or success of its year  2000  readiness
program,  or whether the failure of third party systems or equipment to  operate
properly in the year 2000 will have a material adverse effect upon the Company's
business,  operating results, or financial condition, or require the Company  to
incur unanticipated material expenses to remedy any year 2000 issue.

The foregoing discussion regarding the Company's year 2000 readiness program's
implementation, effectiveness, and cost, contains forward-looking statements 
which are based on management's expectations, determined  utilizing certain
assumptions of future events including third party compliance and other 
factors.  However, there can be no guarantee that these expectations will be 
realized,  and  actual results  could  differ materially from management's 
expections. Specific factors that might cause such material differences include,
but are not limited to, the availability and cost of personnel trained in this
area and other similar uncertainties, and the remediation success of the 
Company's suppliers, service providers, and strategic partners.

Factors That May Affect Future Performance

Statements contained in this document that do not describe historical facts  may
constitute  forward-looking statements.  The Company makes such  forward-looking
statements  under  the provisions of the "safe harbor" section  of  the  Private
Securities  Litigation  Reform  Act  of 1995.   The  forward-looking  statements
contained herein are based on current expectations, but are subject to a  number
of risks and uncertainties which could cause actual results to differ from those
projected.   The  factors that could cause actual results to  differ  materially
include  the  following:  the ability of APC to operate Silcon as  a  less  than
wholly-owned  subsidiary;  APC's  ability  to  successfully  integrate  Silcon's
operations;  the  review and revaluation of acquired R&D by the  Securities  and
Exchange Commission (SEC); the timely development and acceptance of new products
such  as  the  Symmetra  Power  Array; ramp up and  expansion  of  manufacturing
capacity;  general  worldwide economic conditions; growth  rates  in  the  power
protection industry and related industries, including but not limited to the PC,
server,  and  networking industries; competitive factors and pricing  pressures;
changes in product mix; changes in the seasonality of demand patterns; inventory
risks  due  to  shifts  in  market demand; the effects  of  any  other  possible
acquisitions;  component  constraints  and  shortages;  risk  of  nonpayment  of
accounts  receivable; all risks associated with the year 2000  issue  including,
but not limited to, the impact on the Company's business due to internal systems
or  systems of suppliers and other third parties adversely affected by year 2000
problems  as  previously  discussed above; the  uncertainty  of  the  litigation
process  including  risk  of an unexpected, unfavorable  result  of  current  or
threatened litigation; factors associated with international operations; and the
risks described from time to time in the Company's filings with the SEC.

                                       13
<PAGE>
                                                                       FORM 10-Q
                                                              September 27, 1998

PART II - OTHER INFORMATION


ITEM 1.  LEGAL PROCEEDINGS

On  or  about November 6, 1998 General Signal Power Systems, Inc. ("GSPS") filed
suit  against  the Company in Waukesha County Circuit Court in Wisconsin.   GSPS
alleges  interference  with  a  contractual  relationship  with  respect  to   a
distribution agreement between the Best Power division of GSPS and Silcon A/S, a
majority-owned  subsidiary  of  the Company.  GSPS  seeks  unspecified  damages,
costs,  fees,  and injunctive relief.  The Company believes the  lawsuit  to  be
without  merit  and intends to vigorously defend against it.  The  Company  also
believes  the  ultimate disposition of this matter will not  have  a  material
adverse  effect on the Company's consolidated financial position or  results  of
operations  and liquidity.  No provision for any liability that may result  from
this  action  has  been  recognized  in  the  Company's  consolidated  condensed
financial statements included herein.


ITEM 6.  EXHIBITS AND REPORTS ON FORM 8-K

(A)  Exhibits

Exhibit No. 11 - Computation of Earnings per Share (Page 14)
Exhibit No. 27 - Financial Data Schedule (For SEC EDGAR Filing Only;
Intentionally Omitted)

(B)  Reports on Form 8-K

No  reports  on  Form  8-K  were filed by American Power Conversion  Corporation
during the quarter ended September 27, 1998.

                                       14
<PAGE>
                                                                       FORM 10-Q
                                                              September 27, 1998


                                   SIGNATURES
                                        
                                        
      Pursuant  to the requirements of the Securities Exchange Act of 1934,  the
Registrant  has  duly  caused this report to be signed  on  its  behalf  by  the
undersigned thereunto duly authorized.
                                        
                                        
                      AMERICAN POWER CONVERSION CORPORATION
                                        
                            Date:  November 12, 1998
                                        
                                        
                               /s/ Donald M. Muir
                                        
                                 Donald M. Muir
                             Chief Financial Officer
                  (Principal Accounting And Financial Officer)

                                       15
<PAGE>
                                                                       FORM 10-Q
                                                              September 27, 1998
                                                                                
                                                                                
                                                                      EXHIBIT 11

<TABLE>
                      AMERICAN POWER CONVERSION CORPORATION
                        COMPUTATION OF EARNINGS PER SHARE
                  (In thousands except for earnings per share)
<CAPTION>
                                        
                                                     Nine months ended          Three months ended
                                                  September    September     September    September
                                                         27,          28,           27,          28,
                                                       1998         1997          1998         1997
                                                                        (Unaudited)              
                                                                                                 
<S>                                                <C>          <C>            <C>          <C>
Basic                                                                                       
                                                                                            
Net income                                         $100,116     $84,359        $46,618      $36,773
                                                                                            
Basic weighted average shares outstanding            95,412      94,915         95,537       95,154
                                                                                            
Basic earnings per share                            $  1.05     $   .89          $ .49       $  .39
                                                                                            
                                                                                            
Diluted                                                                                     
                                                                                            
Net income                                         $100,116     $84,359        $46,618      $36,773
                                                                                            
Basic weighted average shares outstanding            95,412      94,915         95,537       95,154
                                                                                            
Net effect of dilutive potential common shares                                              
outstanding based on the treasury stock                                                     
method using the average market price                 1,235       1,210          1,324        1,341
                                                                                            
Diluted weighted average shares outstanding          96,647      96,125         96,861       96,495
                                                                                            
Diluted earnings per share                          $  1.04     $   .88       $    .48       $  .38

</TABLE>

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