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                                UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549
                                           
                                 FORM 10-Q/A1
                                           
   [X] Quarterly Report Pursuant to Section 13 or 15(d) of the Securities 
Exchange Act of 1934 for the Quarterly Period Ended September 30, 1997
                                           
                                      or
                                           
   [ ] Transition Report Pursuant to Section 13 or 15(d) of the Securities
Exchange Act of 1934


                        Commission File Number 0-25812
                                           
                                          
                                  PSINET INC.
            (Exact name of Registrant as specified in its charter)
                                           
                                           
             New York                                   16-1353600
   (State or other jurisdiction of                   (I.R.S. Employer
    incorporation or organization)                  Identification No.)


  510 Huntmar Park Drive, Herndon, VA                      20170
(Address of principal executive office)                  (Zip Code)

                                 (703) 904-4100
              (Registrant's telephone number, including area code)  
                                           
                                 Not Applicable
  (Former name, former address and former fiscal year, if changed since last
                                  report date)
                                           

Indicate by check mark whether the registrant (1) has filed all reports 
required 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  
                                                     -----   -----

    Common Stock, $.01 par value - 40,434,933 shares as of October 31, 1997
 (Indicate the number of shares outstanding of each of the issuer's classes of
                common stock, as of the latest practicable date)

                     The Index of Exhibits begins on page 5.

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Item 6.  EXHIBITS AND REPORTS ON FORM 8-K

(a) Exhibits

      The following Exhibits are filed herewith:

      Exhibit 2.1    iSTAR Agreement dated as of November 10, 1997 between 
                     iSTAR Internet Inc. and PSINet Inc. 

      Exhibit 3.1    Certificate of Amendment of Certificate of Incorporation
                     dated as of November 10, 1997      

      Exhibit 4.1    Certificate of Amendment of Certificate of Incorporation 
                     dated as of November 10, 1997 

      Exhibit 10.1   Amendment No. 1 to Deed of 460 Spring Park Technology 
                     Center dated as of June 12, 1997 between JBG/Spring Park 
                     Limited Partnership and PSINet Inc.     

      Exhibit 10.2   Sublease Agreement dated as of June 2, 1997 between LUCAS 
                     INDUSTRIES, INC. and PSINet Inc. and Office Lease Agreement
                     between 3B Limited Partnership and Lucas Industries Inc. 
                     dated as of September 12, 1989
    
      Exhibit 10.3   Master Equipment/Software Rental Agreement 
                     dated as of September 11, 1997 between PSINet and Earthlink
                     Network, Inc. and Change Order Amendment Master 
                     Equipment dated as of September 22 , 1997    

      Exhibit 10.4   Equipment lease dated as of June 30, 1997 between Royal
                     Bank of Canada and PSINet Limited  

      Exhibit 10.5   Employment Agreement dated July 1, 1997 between
                     the Company and Michael Malesardi  

      Exhibit 10.6   Employment Agreement dated August 2, 1997, 1997 between
                     the Company and Tony Aveta    

      Exhibit 10.7   Employment Agreement dated August 4, 1997 between 
                     the Company and Harry Hobbs   

      Exhibit 10.8   First Amendment dated as of September, 10,1997 to the  
                     Amended and Restated Credit Agreement between the Company 
                     and Fleet Bank of Massachusetts, N.A.   

      Exhibit 10.9   Stock Purchase Agreement dated as of November 11, 1997
                     between PSINet Inc. and the
                     purchasers of Series B 8% Convertible Preferred Stock  

      Exhibit 10.10  Registration Rights Agreement dated as of November 11, 1997
                     between PSINet Inc. and the
                     purchasers of Series B 8% Convertible Preferred Stock  

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      Exhibit 11.1   Calculation of Loss per Share and Weighted Average Shares 
                     Used in Calculation for the Three Months Ended 
                     September 30, 1997

      Exhibit 11.2   Calculation of Loss per Share and Weighted Average Shares 
                     Used in Calculation for the Nine Months Ended 
                     September 30, 1997
    
      Exhibit 27     Financial Data Schedule **

      Exhibit 99.1   Risk Factors

      **   Not deemed filed for purposes of Section 11 of the Securities Act of
           1933, Section 18 of the Securities Exchange Act of 1934 and Section
           323 of the Trust Indenture Act of 1939 or otherwise subject to the
           liabilities of such sections and not deemed part of any registration
           statement to which such exhibit relates.

(b) Reports on Form 8-K
    
    On August 1, 1997, the Company filed a Current Report on Form 8-K, dated
    July 31, 1997 relating to its entering into the IRU and Stock Purchase
    Agreement  dated as of July 22, 1997 with IXC Internet Services, Inc.
    ("IXC") and a Joint Marketing and Services Agreement dated as of July 22,
    1997 with IXC.
    
    On August 21, 1997, the Company filed a Current Report on Form 8-K, dated
    August 20, 1997, relating to an amendment to the Company's Shareholder
    Rights Plan in connection with the IRU and Stock Purchase Agreement dated
    as of July 22, 1997 between the Company and IXC.

                                      3

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                                 PSINET INC.
                                FORM 10-Q/A1
                             SEPTEMBER 30, 1997
                                           
                                 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.

                                       PSINet Inc.
    

December 2, 1997                       By: /s/ William L. Schrader
----------------                          ------------------------------------
     Date                                  William L. Schrader
                                           Chairman, President, Chief
                                           Executive Officer and Director

         
December 2, 1997                       By: /s/ Edward D. Postal
----------------                          ------------------------------------
     Date                                  Edward D. Postal
                                           Senior Vice President and 
                                           Chief Financial Officer
                                           (Principal Financial Officer)




                                      4


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                                EXHIBIT INDEX
                                           
Item 6 (a) Exhibits:

Exhibit                       Exhibit Name                              Location
-------                       ------------                              --------

  2.1      iSTAR Agreement dated as of November 10, 1997 between iSTAR 
           Internet Inc. and PSINet Inc. ...............................  ***

  3.1      Certificate of Amendment of Certificate of Incorporation    
           dated as of November 10, 1997 ...............................  ***

  4.1      Certificate of Amendment of Certificate of Incorporation    
           dated as of November 10, 1997 ...............................  ***
                        
  10.1     Amendment No. 1 to Deed of 460 Spring Park Technology 
           Center dated as of June 12, 1997 between JBG/Spring Park 
           Limited Partnership and PSINet Inc. .........................  ***

  10.2     Sublease Agreement dated as of June 2, 1997 between LUCAS 
           INDUSTRIES, INC. and PSINet Inc. and Office Lease Agreement 
           between 3B Limited Partnership and Lucas Industries Inc.    
           dated as of September 12, 1989 ..............................  ***

  10.3     Master Equipment/Software Rental Agreement dated as of  
           September 11, 1997 between PSINet and Earthlink Network, 
           Inc. and Change Order Amendment Master Equipment 
           dated as of September 22 , 1997 .............................  ***

  10.4     Equipment lease dated as of June 30, 1997 between Royal
           Bank of Canada and PSINet Limited ...........................  ***

  10.5     Employment Agreement dated July 1, 1997 between
           the Company and Michael Malesardi ...........................  ***

  10.6     Employment Agreement dated August 2, 1997, 1997 between
           the Company and Tony Aveta ..................................  ***

  10.7     Employment Agreement dated August 4, 1997 between 
           the Company and Harry Hobbs .................................  ***

  10.8     First Amendment dated as of September, 10,1997 to the       
           Amended and Restated Credit Agreement between the Company   
           and Fleet Bank of Massachusetts,
           N.A. .........................................  Sequentially numbered

  10.9     Stock Purchase Agreement dated as of November 11, 1997
           between PSINet Inc. and the purchasers of Series B 8%       
           Convertible Preferred Stock .................................  ***

  10.10    Registration Rights Agreement dated as of November 11,      
           1997 between PSINet Inc. and the
           purchasers of Series B 8% Convertible Preferred Stock .......  ***

                                      5

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Item 6 (a) Exhibits (continued):

Exhibit                       Exhibit Name                              Location
-------                       ------------                              --------

  11.1     Calculation of Loss per Share and Weighted Average Shares   
           Used in Calculation for the Three Months Ended September 30, 
           1997 .........................................................  ***

  11.2     Calculation of Loss per Share and Weighted Average Shares   
           Used in Calculation for the Nine Months Ended September 30, 
           1997 .........................................................  ***
          
  27       Financial Data Schedule ......................................  ***
    

  99.1     Risk Factors .................................................  ***
    


***   Previously filed with the Company's Quarterly Report on Form 10-Q for the 
      fiscal quarter ended September 30, 1997, as filed with the Securities and 
      Exchange Commission.


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