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                                                                    Exhibit 10.8


September 30, 1997                                    



Mr. Edward D. Postal
Senior Vice President and Chief Financial Officer
PSINet Inc.
510 Huntmar Park Drive
Herndon, VA 20170

Dear Ed:

Reference is hereby made to the Amended and Restated Credit Agreement, as 
amended, (the "Agreement") made as of the 10th day of November, 1995 by and 
between PSINet Inc. (f/k/a Performance Systems International, Inc.) ("PSI") 
and Fleet National Bank (f/k/a Fleet National Bank of Connecticut, successor 
by merger to Fleet Bank of Massachusetts, N.A.) (the "Bank").  PSI has 
requested that the Bank amend several financial covenants as follows:

Section 4.22  Quick ratio - For the quarter ending September 30, 1997 a ratio 
not to be less than 1.15:1.00; for the quarter ending December 31, 1997 a 
ratio not to be less than 1:25:1:00; for the quarters ended March 31, 1998, 
June 30, 1998 and September 30, 1998 a ratio not to be less than .90:1.00; 
and thereafter a ratio not to be less than 1.00:1.00.

Section 4.23   Tangible Net Worth - For the quarter ending September 30, 1997 
the requirement shall equal or exceed $55,000,000; for quarter ending 
December 31, 1997 the requirement shall equal or exceed $67,500,000; for 
quarter ending March 31, 1998 the requirement shall equal or exceed 
$70,000,000  Each requirement shall be  increased by (i) 80% of all positive 
net income earned after September 30, 1997 plus (ii) 50% of the net tangible 
proceeds received from the sale by PSI of any shares of its capital stock 
after September 30, 1997, excluding the shares issued to Brown, Simpson et.al.

Section 4.24  Consolidated EBITDA - For the quarter ending September 30, 1997 
the requirement shall be not less than negative $4,000,000; for the quarters 
ending December 31, 1997, March 31, 1998, June 30, 1998, and September 30, 
1998 the requirement shall be not less than negative $8,000,000, negative 
$12,500,000, negative $5,000,000, and positive $4,000,000 respectively.

Section 4.25  Leverage Ratio - For the quarter ending September 30, 1997 a 
ratio not to exceed 1.65:1.00; for the quarter ending December 31, 1997 a 
ratio not to exceed 1.50:1.00; for the quarters ending March 31, 1998, June 
30, 1998 and September 30, 1998, the ratio shall be not greater than 
1:75:1:00, 1:75:1:00 and 1:50:1:00 respectively, subject to the following 
proviso. Total liabilities as defined under section 4.25 shall exclude any 
obligations to deliver additional securities, cash or a combination thereof 
(at the option of PSI) pursuant to the bandwidth transaction with IXC 
Communications Inc.

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Section 4.26  Debt Service Ratio - The ratio of Consolidated EBITDA to Debt 
Service shall, as of the last day of each fiscal quarter commencing with the 
fiscal quarter ending December 31, 1998 equal or exceed 1.25:1.00. Debt 
service as defined under section 4.26 shall exclude any interest accreting as 
a result of any obligations to deliver additional securities, cash or a 
combination thereof (at the option of PSI) pursuant to the bandwidth 
transaction with IXC Communications, Inc. There shall be no debt service 
ratio applicable prior to the fiscal quarter ending December 31, 1998.  

In addition, PSI requests that the Bank extend the Revolving Credit Maturity 
Date until December 31, 1997.

In accordance with the amendments detailed herein PSI shall remit to the Bank 
an amendment fee of $25,000, amount not to include $12,500 already paid.

The Bank hereby consents to these changes. Nothing herein shall be deemed to 
constitute a waiver, release or amendment of any other terms of the 
Agreement. PSI represents and warrants that the execution of this amendment 
has been duly authorized by PSI by all necessary corporate and other action 
and that the execution will not conflict with, violate the provisions of, or 
cause a default or cause an event which, with the passage of time or giving 
of notice or both, could cause a default on the part of PSI under its charter 
documents or by-laws or under any contract, agreement, law, rule, order, 
ordinance, franchise, instrument or other document, or result in the 
imposition of any lien or encumbrance on any property or asset of PSI.

PSI further represents that this letter represents legal, valid and binding 
obligations of PSI, enforceable against PSI in accordance with their 
respective terms. In addition, the statements, representations and warranties 
made in the Agreement continue to be correct as of the date hereof, except 
for those representations which relate to a specific date which are true and 
correct as of such date, and PSI is in compliance with all terms of the 
Agreement. Except as expressly affected hereby, the Agreement remains in full 
force and effect as heretofore.  This amendment supercedes and replaces, in 
its entirety, the letter agreement amendment previously executed by the 
parties dated September 30, 1997.

Ed, we again look forward to continuing our relationship with PSI.  Please 
sign below to evidence your acceptance of this amendment, whereupon this 
amendment shall be a biding agreement between us.


Yours sincerely,                           Agreed and Accepted

Fleet National Bank.                       PSINet Inc.
  
/s/ Thomas W. Davies                       /s/  Edward D. Postal 
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By:     Thomas W. Davies                   By:     Edward D. Postal
Title:  Senior Vice President              Title:  Senior Vice President and
                                                   Chief Financial Officer

                                           Date: 11/14/97
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