<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------

                              JOINT VENTURE AGREEMENT

    THIS AGREEMENT, made and entered into as of this 19th day of September,
1996 by and between PSINet Inc., a corporation organized and existing under the
laws of the state of New York and having its principal place of business at 510
Huntmar Park Drive, Herndon, Virginia 22070 ("PSI"), and Chatterjee Management
Company (doing business as The Chatterjee Group), a corporation organized and
existing under the laws of the state of Delaware and having its principal place
of business at 888 7th Avenue, Suite 3000, New York, New York  10106 ("TCG")
(together, the "Parties").
                                  WITNESSETH THAT:

    WHEREAS, PSI is an Internet service provider offering a wide range of
Internet access services to organizations and individuals worldwide by means of
the PSINet (as defined below);

    WHEREAS, TCG is an experienced investor with European connections and
interests, including, through its Affiliates (as defined below), investments in
the construction of facilities in Europe over which Internet-access services may
be provided; and

    WHEREAS, the Parties desire to establish PSINet Europe (the "EJV"), a joint
venture to be formed by PSI, together with the TCG Designee (as defined below).
    NOW, THEREFORE, in consideration of the mutual promises and covenants
contained herein, the parties agree as follows:

                              Article 1.   Definitions

    1.1. Terms defined in this Article 1 and elsewhere, in this Agreement shall
have the same meaning throughout this Agreement.  Defined terms may be used in
the singular or the plural.  All references to periods of days are to periods of
calendar days.

    1.2. "Affiliate" of a Person means any Person which directly or indirectly
controls, is under common control with, or is controlled by, such Person, where
"control" means the power and ability to direct the management and policies of
the controlled Person through ownership of voting shares of the controlled
Person or by contract or otherwise.  With respect to TCG, the term "Affiliate"
shall include one or more of Purnendu Chatterjee, George Soros or Soros Fund
Management or Affiliates 

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thereof, and any Person for which any such Person acts as investment advisor 
or investment manager.

    1.3. "Board" means the Board of Directors or a comparable body of the EJV.

    1.4. "Buildout Funding Date" means the date on which the EJV has identified
the initial markets for buildout of the Network, approved an initial business
plan and has a reasonable business need to have access to the Software, the
Technical Information and the Trademarks.

    1.5. "Controlling Interest" means an interest conferring on the party
holding such interest the power and ability to direct the management and
policies of the controlled enterprise through ownership of voting shares of the
controlled enterprise or by contract or otherwise.  For purposes hereof, no such
interest of 5% or less shall be deemed to be a Controlling Interest.

    1.6. "Government Approval" of any action to be taken by either Party means
such approval of or confirmation or consent to such action, together with such
licenses, permits or other permissions reasonably required for such action, all
as the statutes, decrees, regulations and rulings of governmental authority
(collectively, "Legal Authority") within the European Union, any sovereign
European country or the United States, as the case may be, may require to be
obtained in connection with said action from such governmental authority or from
political subdivisions thereof.  Whenever any form of "Government Approval" is
used herein, it shall be interpreted and construed to include the requirement
that such approval be in form and substance acceptable to the Parties.

    1.7. "Internet" means the open global network of interconnected commercial,
educational and governmental computer networks that utilize TCP/IP.

    1.8. "Licensed Intellectual Property" means the Technical Information and
the Trademarks.

    1.9. "Lien" means, with respect to any property or asset, any mortgage,
lien, pledge, deed of trust, charge, security interest, encumbrance or other
adverse claim of any kind with respect to such property or asset.

    1.10.     "On-line Services" means commercial information services that
offer a computer user access through a modem to a specified slate of
information, entertainment and communications menus.  On-line Services may or
may not utilize the PSINet or the Software.

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                                              CONFIDENTIAL TREATMENT REQUESTED
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The symbol "--" indicates that a confidential portion has been omitted and 
filed separately with the Securities and Exchange Commission


    1.11.     "Person" means any individual, corporation, partnership, firm,
joint venture, association, limited liability company, trust, unincorporated
organization or other entity.

    1.12.     "POP" means an interlinked group of modems, routers and other
computer equipment referred to as a "point of presence," located in a particular
city or metropolitan area, that allows a nearby subscriber to access the
Internet through a local telephone call.

    1.13.     "Protocol" means a formal description of message formats and the
rules two or more machines must follow to exchange messages.

    1.14.     "PSINet" means the high-performance computer network operated by
PSI that utilizes an advanced TCP/IP-based, Asynchronous Transfer Mode,
Integrated Services Digital Network and Switched Multi-megabit Data Service
compatible frame relay network comprised of POPs that are networked through
advanced frame relay technology to create a network that allows local access to
the Internet in the localities where POPs are located.

    1.15.     "PSI UK" means PSINet UK Limited, a corporation organized under
the laws of the United Kingdom.

    1.16.     "Securityholder" means a holder of equity interests in the EJV.

    1.17.     "Software" means any commercially available end user software
marketed by PSI now or in the future that may be necessary, useful or
appropriate for distribution in connection with the operation of the Network and
any related software products and network services in Europe, together with all
error corrections, updates, upgrades, enhancements, new versions, derivatives,
add-ons and replacements made commercially available with respect to such
software.

    1.18.     "TCG Designee" means an Affiliate of TCG that is managed and
controlled by TCG--------------------------------------------------------------
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------------------------------------------------------.

    1.19.     "TCP/IP" means the Transmission Control Protocol/Internet
Protocol, a compilation of network- and transport-level Protocols that allow
computers with different architectures and operating system software to
communicate with other computers on the Internet, and any successor Protocol
serving similar functions.

    1.20.     "Technical Information" means the proprietary processes,
improvements, trade secrets, designs, data, plans, specifications, know-how,
network 

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or operating software, operating experience and other information,
whether patented or unpatented, copyrighted or uncopyrighted that is presently
owned or may be developed by PSI relating to the design, configuration and
technical specifications of the Internet network, which are necessary, useful or
appropriate for the establishment and operation of the Network in Europe;
provided, however, that the Technical Information shall not include the
Software.

    1.21.     "Trademarks" means (a) "PSI," "PSINet," "InterFrame," "PSILink,"
"UUPSI" and all other registered trademarks now owned or subsequently acquired
or developed by PSI that are used in connection with the marketing, distribution
and sale of Internet-access and related services and (b) "Internet Inside!,"
"InternetWarehouse," "InterTainment," "PSICable," "InterRamp," "LAN-dial,"
"LAN-ISDN," "LAN On Demand," "InterMAN," "SecureStream," "Pipeline," "PSIWeb,"
"Internaut," "Instant InterRamp," "PSI IntrAnet" and all other service marks now
owned or subsequently acquired or developed by PSI that are used in marketing,
distributing and selling Internet-access and related services.

    1.22.     The following terms are defined in the Articles or Sections set
forth below:

              "Appreciated Value" - Section 4.4

              "Customers" - Section 2.2(b)

              "Disclosing Party" - Section 21.1

              "EJV" - Recitals

              "Force Majeure" - Section 6.1

              "Initial Funding" - Section 4.1

              "Investments" - Section 4.5

              "Legal Authority" - Section 1.5

              "License Agreement" - Section 4.1(a)

              "License" - Section 12.2(c)

              "LJV" - Section 5.2

              "Measurement Date" - Section 4.4

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              "Network" - Section 2.2(a)


              "NJV" - Section 4.6


              "Offer" - Section 6.2

              "Offered Securities" - Section 6.2

              "PSI Filing" - Section 12.2(a)

              "Qualifying IPO" - Section 3.2

              "Receiving Party" - Section 21.1

              "Registration Rights Agreement" - Section 5.4.

              "Securities" - Section 6.1

              "Selling Securityholder" - Section 6.2

              "Services Agreement" - Article 9

              "Significant Securityholder" - Section 6.2

              "Subsidiary Business" - Section 12.2(c)

              "Subsidiary Financial Statements" - Section 12.2(e)

              "Subsidiary Quarterly Financial Statements" - Section 12.2(e)

              "Subsidiary Securities" - Section 12.2(d)

              "TCG Designee" - Recitals

              "Transfer" - Section 6.1

                                Article 2.   Purpose

    2.1. The purpose of this Agreement is to provide for the establishment,
ownership and operation of the EJV by PSI and the TCG Designee.

    2.2. The purpose of the EJV will be to engage in the following business
activities:

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         (a)  acquiring and importing network components such as equipment and
circuits and building a network in Europe (the "Network") to constitute a
segment of the PSINet global network;

         (b)  connecting the Network to the global PSINet infrastructure so as
to support unlimited carriage of outbound and inbound Internet traffic within a
particular European country, from country to country in Europe and to the rest
of the world for businesses, schools and other organizations and individuals
wishing to purchase Internet services (collectively, "Customers"), and operating
the Network;

         (c)  establishing POPs throughout Europe;

         (d)  providing sales, marketing, customer support, customer service,
and billings and collections for dialup and circuit-based services to Customers;

         (e)  selling PSINet services (i) in Europe as the EJV's primary
business area and (ii) outside Europe to the extent permitted under the Services
Agreement (for example, but not by way of limitation, for the purposes of
selling PSINet services outside Europe to multinational companies based in
Europe) under the terms and conditions to be set forth in detail in the Services
Agreement;

         (f)  providing services (including, without limitation, Internet,
intranet, other PVC-based services and any other services offered from time to
time by PSI), World Wide Web hosting services, network security services,
electronic commerce and all related services to Customers;

         (g)  engaging in any other lawful business activity that is approved
in advance by the Board in accordance with this Agreement; and

         (h)  engaging in any and all acts, things, businesses and activities
that are related, incidental or conducive directly or indirectly to the
attainment of the foregoing objectives.

                           Article 3.   The Joint Venture

    3.1. As soon as reasonably practicable after the effective date of this
Agreement, PSI and the TCG Designee shall cooperate to establish the EJV in such
jurisdiction and in such form as they may deem appropriate for the purposes of
the EJV, PSI and the TCG Designee, and in accordance with such jurisdiction's
applicable law.

    3.2. The organizational documents of the EJV shall be as agreed by PSI and
the TCG Designee, and PSI and the TCG Designee shall cause such documents to be

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                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------
The symbol "--" indicates that a confidential portion has been omitted and 
filed separately with the Securities and Exchange Commission


amended from time to time as may be required to ensure that they at all times
conform with the terms and conditions of this Agreement and any amendments
hereto.  The Board shall consist of five members, with PSI and the TCG Designee
each designating two members and the fifth member being chosen by mutual
agreement of PSI and the TCG Designee.  Certain major actions relating to the
EJV and PSI UK, as set forth in Exhibit A, will not be taken without the
approval of the TCG directors or the TCG Designee, as the case may be,
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    3.3. The duration of the EJV shall be perpetual, subject to the provisions
of applicable law, the EJV's organizational documents and this Agreement.

                       Article 4.   Capitalization of the EJV

    4.1. Initial Funding.  At the initial capitalization of the EJV (the
"Initial Funding"):

         (a)  PSI shall contribute ------------------- to the EJV in exchange
for   ----------- of the EJV's initial equity.

         (b)  The TCG Designee shall contribute ------------------ to the EJV
in exchange for --------- of the EJV's initial equity.  

    4.2. Initial Buildout Funding.  Upon the Buildout Funding Date:
         (a)  PSI shall contribute ------------------ to the EJV.  The EJV
shall use such contribution, together with -------------- from the Initial
Funding, within 10 days from the Buildout Funding Date to purchase from PSI a
license to use the Software, Technical Information and Trademarks in Europe
pursuant to a license agreement (the "License Agreement") containing
substantially the terms and conditions set forth in Exhibit C attached hereto.

         (b)  The TCG Designee shall contribute ------------------ to the EJV.

         (c)  Following the contributions set forth in this Section 4.2, PSI
and TCG will own -------- and -----------, respectively, of the equity interests
in the EJV.

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                                              CONFIDENTIAL TREATMENT REQUESTED
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The symbol "--" indicates that a confidential portion has been omitted and 
filed separately with the Securities and Exchange Commission


    4.3. PSI UK Call/Put.  At the Initial Funding, PSI and the EJV shall enter
into a call/put agreement granting the EJV the right to purchase from PSI up to
100% of the outstanding capital stock of PSI UK in exchange for newly issued
equity interests in the EJV.  The aggregate amount of PSI UK's capital stock
shall be valued at -------------------, regardless of the date of exercise. 
Such call right may be exercised by the EJV Board from time to time in whole or
in part at any time after the Initial Funding; provided, however, that the EJV
Board will not exercise such call until the earliest of the following to occur:
         
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Pursuant to the call/put agreement, PSI shall also have the right to put at any
time all or any portion of the outstanding capital stock of PSI UK it then holds
to the EJV, at the same times and on the same terms and conditions; provided,
however, that upon any exercise of such put by PSI, TCG will have the right to
require PSI to put all PSI's remaining interest in PSI UK to the EJV if TCG, on
or prior to the completion of such put, has made the full amount of all capital
contributions required under Section 4.4.  The equity interests in the EJV held
by PSI as a result of the exercise of the call/put right shall at no time be
equal to or greater than the equity interests in the EJV held by TCG and its
Affiliates without the consent of PSI.

    4.4. TCG Designee Capital Contributions.  The TCG Designee, through TCG,
hereby irrevocably commits to make additional capital contributions to the EJV
in an aggregate amount of up to -------------------, as determined from time to
time by the Board, and as provided in the annual budgets and plans approved by
the Board.  Notwithstanding the foregoing, TCG or the TCG Designee shall have
the right (that 

                                       8
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                                              CONFIDENTIAL TREATMENT REQUESTED
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The symbol "--" indicates that a confidential portion has been omitted and 
filed separately with the Securities and Exchange Commission


is, without any call for capital by the Board, the EJV or PSI)
to accelerate at any time after the signing of this Agreement any capital
contributions to the EJV  (or if the EJV has not yet been organized, payments to
PSI), so long as the aggregate amount of investments made pursuant to this
Agreement (including without limitation pursuant to Sections 4.1(b), 4.2(b) and
this Section 4.4) does not exceed --------------------.  The parties acknowledge
that upon such investment, they will treat those amounts as invested for all
purposes under this Agreement, including Section 5.3.

    4.5. Adjustment to PSI Funding. -------------------------------------------
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Within 15 days of the earlier of (i) the sale, transfer or exchange
of the TCG Designee's interests in the EJV in connection with the acquisition
(whether through merger or acquisition of the Securities) by a third party of
the EJV (ii) ----- years from the Initial Funding and (iii) any dissolution of
the EJV (in any such case, the "measurement date"), the EJV shall engage, at its
expense, an investment banking firm of nationally recognized standing or another
appraiser mutually acceptable to PSI and the TCG Designee to appraise the fair
market value of the equity interest in the EJV held by the TCG Designee and its
Affiliates as of the measurement date.  Such appraisal shall not take into
account any control premium.

    4.6. -----------------------------------------------------------------------
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------------------------------------

    4.7. Valuation of Contributions.  Following the capital contributions
described in Sections 4.1 and 4.2, any contributions to the capital of the EJV
by PSI or TCG will be valued for the purposes of allocation of equity interests
on the same basis as the contributions set forth in such sections (i.e., the
contribution of the equity 
                                       9
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                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------
The symbol "--" indicates that a confidential portion has been omitted and 
filed separately with the Securities and Exchange Commission


in PSI UK will be valued as set forth in Section 4.3, and monetary 
contributions will be treated at face value).

                            Article 5.   Puts and Calls

    5.1. PSI EJV Buyout Call.  If any Person or group of Persons acquires all
or substantially all the common stock of PSI, PSI shall have the right to
purchase the TCG Designee's equity interest in the EJV.  PSI may exercise such
right upon notice to the TCG at least 15 days and not more than 30 days prior to
the closing of such acquisition.  At or prior to the closing of such
acquisition, PSI shall pay the TCG Designee in securities (or such other
consideration as is payable to PSI shareholders) and/or cash, at the TCG
Designee's option, for such equity interest in an amount equal to (a) the price
paid per share by the acquiring Person or group for the PSI common stock,
divided by the volume-weighted average trading price per share of the PSI common
stock, as shown on the Bloombergs historical price screen, during the 30-day
period beginning 40 days prior to announcement of such acquisition, multiplied
by (b) the appraised fair market value of the TCG Designee's equity interest in
the EJV, as determined in accordance with Section 4.4; provided that the
aggregate value of the consideration paid to the TCG Designee shall be at least
equal to the sum of the Appreciated Value and a ------- per annum return
thereon, based on a minimum of ---- ------- from the Initial Funding (regardless
of when such acquisition actually occurs).

    5.2. PSI LJV Control Option.  The Parties agree to implement as soon as
practicable a structure that would allow PSI the right to a call on the majority
interest in any of the local joint venture ("LJV") companies which may be
acquired by the EJV as part of the pan-European Network; provided, however, that
such structure is tax neutral to the EJV and the TCG Designee and its
Affiliates.  Any such call would be subject to a similar call back, valued at
PSI's cost basis in the LJV, prior to a change of control in the EJV, including
an acquisition or an initial public offering.

    5.3. TCG Downside Put.  TCG or the TCG Designee shall have the right to
require PSI to issue to TCG or the TCG Designee in exchange for the Investments
a number of shares of PSI common stock calculated by dividing the amount of the
Investments by the closing price of PSI common stock on the trading day
-------------- --------------------------------------------.  TCG or the TCG
Designee, as the case may be, may exercise such right at any time upon written
notice to PSI, except (a) between the Initial Funding and October 1, 1997 and
(b) after the organizational meeting relating to a proposed initial public
offering of equity interests in the EJV and prior to the earlier of a decision
of the Board not to proceed with such an offering or consummation of such an
offering; provided, however, that notwithstanding such exceptions and anything
else contained in this Agreement (including, without limitation, any notice of
exercise by PSI of the purchase rights described in Section 

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5.1), the TCG Designee may exercise such right (i) at any time immediately 
prior to the closing of the acquisition of all or substantially all the 
assets or common stock of PSI or (b) upon any material adverse change in the 
EJV or its business. The closing of the exchange of TCG's or the TCG 
Designee's and its Affiliates' equity interests in the EJV for PSI common 
stock shall take place within 10 days of delivery of written notice to PSI of 
TCG's or the TCG Designee's exercise of its put right under this Section 5.3.

    5.4. Registration Rights.  PSI and TCG will enter into a registration
rights agreement (the "Registration Rights Agreement") substantially in the form
attached as Exhibit D hereto.

    5.5. Reservation of Shares.  PSI shall at all times have reserved a
sufficient number of shares of its common stock to satisfy its obligations under
this Agreement.

                          Article 6.   Transfer of Shares

    6.1. Restrictions on Transfer.  Except as otherwise specifically set forth
herein, no Securityholder may sell, assign, transfer, pledge, hypothecate,
mortgage, encumber or dispose of (collectively, "Transfer") all or any part of
any securities of the EJV (collectively, the "Securities") unless such
Securityholder has complied with the provisions of this Article 6; provided,
however, that TCG may transfer any such securities to any of its Affiliates.

    6.2. Right of First Offer.  If a Securityholder (a "Selling
Securityholder") desires to Transfer any or all of its Securities (the "Offered
Securities"), it shall first make a written offer to sell the Offered Securities
(the "Offer") to all Securityholders (other than the Selling Securityholder)
then holding more than 5% of the equity securities of the EJV (a "Significant
Securityholder").  A statement attached to the Offer shall set forth a full
disclosure of the Offer, including (a) a statement of intention to Transfer,
(b) the number of Offered Securities, and (c) the terms and conditions of the
proposed Transfer, including the purchase price for the Offered Securities. 

    6.3. Election to Purchase; Closing.  Within 30 days after delivery of the
Offer, the Significant Securityholders may elect to purchase, at the price and
on the terms specified in the Offer, the Offered Securities by giving written
notice to the Selling Securityholder.  The closing of such purchase shall occur
on a date mutually acceptable to the parties thereto within 30 days after such
acceptance.  At such closing, the Significant Securityholders having elected to
purchase shall pay the Selling Securityholder the purchase price as specified in
accordance with Section 6.2(c), and the Selling Securityholder shall
simultaneously deliver the 

                                       11
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certificates representing the Securities being transferred and all other 
evidence of transfer as may reasonably be requested by the purchasing 
Securityholder.

    6.4. Transfer to Third Parties.  If any of the Offered Securities remain
unpurchased following the time periods specified above, the Selling
Securityholder may Transfer such remaining Offered Securities to any third
party; provided, however, that the other Party shall have first consented to the
transfer to such third party, which consent shall not be unreasonably withheld. 
Such transfer shall be made only in strict accordance with the terms set forth
in the Offer and shall be completed within 90 days following the expiration of
the time provided for the purchase of the Offered Securities by the purchasing
Securityholders, after which time any such Transfer shall again become subject
to all the restrictions of this Agreement and the organization documents of the
EJV.  The transferee shall agree in writing to be bound by the terms of this
Agreement.

    6.5. Ineffective Transfers.  No Transfer of any right, title or interest in
any of the Securities shall be effective, and the EJV shall not record or
recognize any such Transfer, until there has been compliance with the provisions
of this Agreement and the organization documents of the EJV.  If no Offer is
made as herein required, the EJV and the Securityholders may nevertheless
exercise their rights hereunder as to the Offered Securities, and they may do so
at any time, even after the purported Transfer of the Securities.  

    6.6. Termination.  The restrictions contained in this Article 6 shall
terminate upon consummation of a Qualifying IPO.

    6.7. Legends.  During the term of this Article 6, each certificate
representing interests in the EJV shall bear the following or similar legend:

         "Transfer of the interests represented by this certificate is
         restricted pursuant to the Joint Venture Agreement dated September __,
         1996, between PSINet Inc. and The Chatterjee Management Company, a
         copy of which is on file at the principal office of the Company in
         __________."

              Article 7.   Meetings and Resolutions of Securityholders

    The Board shall decide the time and place for convening all meetings of the
Securityholders, except where the law of the jurisdiction of organization of the
EJV provides otherwise, and notice thereof shall be given as set forth in the
EJV's organization documents.

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                Article 8.   Basic Corporate and Operating Policies

    8.1. The Parties agree to vote their shares and to cause their
representatives to effectuate the policies set forth below during the term of
this Agreement.

    8.2. The books and records of the EJV and PSI UK shall be maintained in
accordance with U.S. and U.K. generally accepted accounting principles,
respectively, and shall accurately reflect the EJV's financial position.  Such
records and supporting documents shall be available for inspection by the
Parties, or their designees, at all reasonable times.  Each of the EJV and PSI
UK shall send an English version of its quarterly and annual audited (solely as
to the EJV) financial statements to the Parties as soon as practicable after
such financial statements become available (and in no event more than 45 days
after the end of the quarter and 90 days after the year end).  The EJV and PSI
UK shall also send the Parties monthly unaudited financial reports in English.
    8.3. The EJV's fiscal year shall begin on the first day of January and end
on the last day of December of each year; provided, however, that the first
fiscal year shall begin on the date on which the EJV is incorporated and shall
end on the last day of December immediately following.  

    8.4. Only directors who are not employees of the Parties (e.g., independent
directors or directors serving in a management capacity with the EJV) will be
compensated by the EJV; provided, however, that all directors may be reimbursed
for such travel and other expenses as may reasonably be incurred by them in
performing their duties to the EJV.

    8.5. After an initial start-up phase, the EJV shall be operated as a
stand-alone company with its own administrative, technical, sales, marketing and
engineering staff and professional management working on a full-time basis.  

                          Article 9.   Services Agreement

    PSI will provide resources to the EJV pursuant to a Services Agreement (the
"Services Agreement") to be entered into with the EJV at the Initial Funding
containing substantially the terms and conditions set forth in Exhibit B
attached hereto.  The Parties may provide the EJV with additional assistance on
a transitional basis as requested by the Board.

                              Article 10.   Noncompete

    Except as specifically agreed to in writing by the Parties, PSI agrees, and
will cause its Affiliates, and TCG agrees, and will cause the Affiliates that it
Controls, not 

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to compete with, or own directly or indirectly a Controlling
Interest in any Person that competes with, the Internet-related activities of
the EJV in Europe (except for those countries in which the Board determines not
to pursue doing business) during the term of this Agreement and for a period of
two years from the earlier of (i) the expiration or termination hereof and
(ii) the divestiture by such party of its entire interest in the EJV. 
Notwithstanding the foregoing, TCG and its Affiliates may own equity interests
in any such competitor so long as no employees of either TCG or any of its
Affiliates are also employees of such competitor; provided that this sentence
will not diminish any fiduciary obligation that TCG or its Affiliates may have
to the EJV under applicable law.  For purposes of this Article 10, "Affiliate"
shall not include the EJV, PSI UK or, solely with respect to business in the
Netherlands, the NJV.

                       Article 11.   Conditions to Investment

    The obligations of the Parties and the EJV to proceed with any investment
under Sections 4.1, 4.2 or 4.3 pursuant to this Agreement are subject to the
satisfaction on or prior to the date of such investment of all the following
conditions, any one or more of which may be waived in whole or in part by the
Party entitled to the benefit of such conditions:

         (a)  The representations and warranties contained in Article 12 shall
have been true and accurate as of the date of signing of this Agreement and
shall be true and accurate in all material respects on and as of the date of
such investment with the same effect as though made on and as of such date,
except for such changes, if any, as may be agreed to in writing by the Parties.

         (b)  Each of the Parties shall have obtained all Government Approvals
required to be obtained by it for or in connection with the transactions
contemplated hereby, and all consents and approvals, if any, of third parties,
and no such Government Approval or third-party approval shall have been
withdrawn or suspended.

         (c)  On the date of such investment, there shall be no effective
injunction, writ, restraining order or any other order of any nature issued by a
court or Legal Authority of competent jurisdiction directing that any of the
transactions provided for in this Agreement or any of the agreements
contemplated by this Agreement not be consummated as herein or therein provided.

         (d)  On the date of such investment, there shall be no action or
proceeding pending or threatened by or before any court or other judicial,
administrative or regulatory body to restrain or prohibit the transactions
contemplated by this Agreement or any of the agreements contemplated by this
Agreement.

                                       14
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------

         (e)  Since the date of execution of this Agreement, there shall not
have occurred as of the  date of such investment any material adverse change in
the ownership of the Licensed Intellectual Property, or any material adverse
change in the key personnel responsible for the engineering, design and
construction of the Network.

          (f) Each Party shall have executed and delivered or caused to be
executed and delivered any agreements or instruments required by this Agreement
(including, without limitation, the Registration Rights Agreement, the License
Agreement and the Services Agreement) or appropriate in order to consummate the
transactions contemplated hereby, in each case on terms substantially consistent
with those set forth in this Agreement, and such agreements shall remain in
effect.

                    Article 12.   Representations and Warranties

    12.1.     Each Party hereto represents and warrants to the other Party as
follows:  (a) it is duly organized and validly existing under the laws of its
place of incorporation; (b) it has full corporate power and authority and has
taken all corporate action necessary to enter into and perform this Agreement;
(c) the execution and performance by it of its obligations hereunder will not
constitute a breach of, or conflict with, any other material agreement or
arrangement, whether written or oral, by which it is bound; (d) to the best of
its knowledge, it has complied in all material respects with all laws,
regulations, orders, judgments or decrees of any domestic or foreign court or
Legal Authority applicable to it; (e) no representation or warranty made in this
Agreement, or in any exhibit, schedule, certificate, list or other instrument
furnished or to be furnished pursuant to this Agreement, or in connection with
the transactions contemplated hereby, contains or will contain any untrue
statement of a material fact or omits or will omit to state a material fact
necessary in order to make the statements contained herein or therein not false
or misleading; and (f) this Agreement is its legal, valid and binding
obligation, enforceable in accordance with the terms and conditions hereof
(subject to applicable laws of bankruptcy and moratorium); and (g) no broker,
finder or investment banker is entitled to any brokerage, finder's or other fee
in connection with this Agreement or the transactions contemplated hereby based
on arrangements made by it or on its behalf.  

    12.2.     PSI represents and warrants as follows:

         (a)  PSI Filings; No Material Adverse Change.  No filing by PSI with
the U.S. Securities and Exchange Commission (a "PSI Filing"), contains or will
contain any untrue statement of a material fact or omits or will omit to state a
material fact necessary in order to make the statements contained herein or
therein not false or misleading as of the respective dates thereof, and there
has been no material adverse 

                                       15
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------

change to the business, results of operations, financial condition or 
prospects of PSI since the date of the most recent PSI Filing prior to the 
date hereof.

         (b)  Organization, Good Standing, Etc. of PSI UK.  (i) PSI UK is a
corporation duly organized and validly existing under the laws of the United
Kingdom; (ii) PSI UK has full corporate power and authority and has taken all
corporate action necessary to own and operate its properties and carry on its
intended business; (iii) the execution and performance by PSI of its obligations
hereunder will not constitute a breach of, or conflict with, any other material
agreement or arrangement, whether written or oral, by which PSI or the PSI UK is
bound; and (iv) to the best of PSI's knowledge, PSI UK has complied in all
material respects with all laws, regulations, orders, judgments or decrees of
any domestic or foreign court or Legal Authority applicable to it if the failure
to comply would have a material adverse effect on the current or planned
business of PSI UK.

         (c)  Licenses, Permits, Authorizations, Etc. of PSI UK.  PSI UK has
received all currently required governmental approvals, authorizations,
consents, licenses, orders, registrations and permits of all agencies, whether
local or national (the "Licenses"), in each case necessary for the conduct of
its (the "Subsidiary Business"), if the failure to obtain any such License would
have a material adverse effect on the current or planned business of PSI UK.  

         (d)  Capitalization of PSI UK.  As of the date hereof, PSI UK has
authorized capital stock of 1,000 ordinary shares, of which 2 shares are issued
and outstanding.  All outstanding ordinary shares of PSI UK have been duly
authorized and validly issued, are fully paid and nonassessable (except any
assessment that is required by the laws of the United Kingdom and is not
material), and are owned by PSI.  Except as described in this Section 12.2(d),
there are no outstanding (i) shares of capital stock or voting securities of PSI
UK, (ii) securities of PSI UK convertible into or exchangeable for shares of
capital stock or voting securities of PSI UK or (iii) options or other rights to
acquire from PSI UK, or other obligation of PSI UK to issue, any capital stock,
voting securities or securities convertible into or exchangeable for capital
stock or voting securities of PSI UK (the items in clauses (i), (ii) and (iii)
being referred to collectively as the "Subsidiary Securities").  There are no
outstanding obligations of PSI or any of its Affiliates to acquire any
Subsidiary Securities.

         (e)  Financial Statements of PSI UK. PSI has previously delivered to
TCG financial statements of PSI UK for the fiscal year ended December 31, 1995
(the "Subsidiary Financial Statements").  The Subsidiary Financial Statements
are accurate and present fairly in all material respects the financial position
and results of 

                                       16
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------

operations of PSI UK as of December 31, 1995 in accordance with U.K. 
generally applied accounting principles consistently applied.

         PSI has furnished to TCG quarterly financial statements of PSI UK for
the quarter ended June 30, 1996 (the "Subsidiary Quarterly Financial
Statements").  The Subsidiary Quarterly Financial Statements are accurate and
present fairly in all material respects the financial position of PSI UK as of
June 30, 1996 in accordance with U.K. generally accepted accounting principles
consistently applied.

         Since December 31, 1995, except as contemplated by this Agreement, the
Subsidiary Business has been conducted in the ordinary course consistent with
past practices and there has not been any event, occurrence, development or
state of circumstances or facts relating to PSI UK that has had or could
reasonably be expected to have a material adverse effect on the Subsidiary
Business.

         (f)  No Undisclosed Material Liabilities of PSI UK.  There are no
liabilities of PSI UK of any kind whatsoever, whether accrued, contingent,
absolute, determined, determinable or otherwise, and there is no existing
condition, situation or set of circumstances that could reasonably be expected
to result in such a liability, other than liabilities provided for in the
Subsidiary Financial Statements and other than liabilities that, individually or
in the aggregate, will not have a material adverse effect on PSI UK.

         (g)  Contracts of PSI UK.  PSI shall have made available for the
review of TCG prior to the Initial Funding true and complete originals or
photocopies of all material contracts, oral or written, to which PSI UK is a
party, including, without limitation, all agreements, contracts or
understandings between PSI and PSI UK.  All such contracts are valid and in full
force and effect, PSI UK has performed all material obligations imposed on it
thereunder, and there are not, under any of such contracts, any defaults or
events of default on the part of PSI UK or, to the knowledge of PSI, any other
party thereto that would materially adversely affect the business, assets or
financial condition of PSI UK, or that could reasonably be expected to
materially adversely affect the business prospects of PSI UK.  PSI UK has not
received notice, and PSI is not otherwise aware, that any party to any such
material contract intends to cancel, terminate or refuse to renew such material
contract or to exercise or decline to exercise any option or right thereunder.

         (h)  Claims and Legal Proceedings Against PSI UK.  There are no
material claims, actions, suits, arbitrations, proceedings or investigations
pending or, to the knowledge of PSI, threatened against PSI or PSI UK with
respect to the Subsidiary Business before or by any Legal Authority or other
Person.  There are no outstanding or unsatisfied judgments, orders, decrees or
stipulations to which PSI or 

                                       17
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------

PSI UK is a party that involve the transactions contemplated herein or that 
would individually or in the aggregate have a material adverse effect on the 
business, assets or financial condition of PSI UK or that could reasonably be 
expected to have a material adverse effect on the business prospects of PSI 
UK.

         (i)  Patents, Trademarks, Etc. PSI UK owns or has all necessary
licenses or rights within its jurisdiction to use:

              (i)  all trademarks, trade names, copyrights, patents, patent
applications, technology and other intellectual property rights now used by PSI
UK and
              (ii) all formulae, franchises, processes, techniques and
manufacturing know-how and all trademarks, trade names, copyrights, patents,
patent applications, technology and other intellectual property rights used in
connection with services now being or intended to be offered and sold by PSI UK.

                         Article 13.   Term and Termination

    13.1.     This Agreement shall continue in effect until terminated pursuant
to this Article 13 or by mutual agreement of the Parties.

    13.2.     This Agreement shall be terminable forthwith upon the sending of
notice in writing upon the occurrence of one or more of the following events:

         (a)  by either Party, if any required Government Approval has not been
obtained within six months of the date hereof or if any subsequent enactment of
law or regulation or any subsequent act of a Legal Authority in the European
Union or the United States shall, in the reasonable opinion of the adversely
affected Party, (i) make performance of this Agreement impossible or
unreasonably expensive or unreasonably difficult for said Party, (ii) alter the
rights and obligations of the Parties from those agreed and contemplated by this
Agreement, or (iii) interfere with the benefits contemplated herein to be
received by such Party;

         (b)  by either Party, if the other Party commits a material breach of
any of its obligations under this Agreement, which shall not have been remedied
within 60 days from the giving of written notice requiring such breach to be
remedied;

         (c)  by either Party, if the other Party becomes incapable, for a
period of 60 days of performing any of its obligations under this Agreement
because of Force Majeure (as defined below);

                                       18
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------

         (d)  by either Party, if the other Party commences a voluntary case or
other proceeding seeking liquidation, reorganization or other relief with
respect to itself or its debts under any bankruptcy, insolvency or other similar
law now or hereafter in effect or seeking the appointment of a trustee,
receiver, liquidator, custodian or similar official of it or of any substantial
part of its property, or shall consent to any such relief or to the appointment
of or taking possession by any such official in an involuntary case or other
proceeding commenced against it, or shall make a general assignment for the
benefit of creditors, or shall fail generally to pay its debts as they become
due, or shall take any corporate action to authorize any of the foregoing;

         (e)  by either Party, if the other Party has an involuntary case or
other proceeding commenced against it seeking liquidation, reorganization or
other relief with respect to it or its debts under any bankruptcy, insolvency or
other similar law now or hereafter in effect or seeking the appointment of a
trustee, receiver, liquidator, custodian or other similar official of it or any
substantial part of its property, and such involuntary case or other proceeding
remains undismissed and unstayed for a period of 90 days; or an order for relief
is entered against such Party under applicable bankruptcy laws as now or
hereafter in effect;

         (f)  by either Party, if the other Party is unable to pay its debts as
they become due, has explicitly or implicitly suspended payment of any debts as
they become due (except debts contested in good faith), or if the creditors of
such Party have taken over its management;

         (g)  by any Party, in the event of a material breach of the License
Agreement or the Services Agreement by the other Party, and the continuance
thereof after the lapse of all relevant cure periods; or

         (h)  by TCG, if PSI UK experiences any of the events described in
Section 13.2(d), (e) or (f) while under the control of PSI or its Affiliates
(other than the EJV).

    13.3.     If this Agreement is terminated pursuant to Section 13.2, then
the License Agreement and the Services Agreement shall terminate at the option
of the EJV.

                     Article 14.   Consequences of Termination

    14.1.     Termination of this Agreement shall be without prejudice to the
accrued rights and liabilities of the Parties at the date of termination, unless
waived in writing by mutual agreement of the Parties.

                                       19
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------

    14.2.     Upon termination of the License Agreement, each Party shall (at
the request of the other Party) take all steps necessary to ensure that the name
of the EJV is immediately changed so that it no longer contains any reference to
any trade name, trademark, service name or service mark then owned by the other
Party or any of its Affiliates (other than the EJV).

    14.3.     If this Agreement is terminated by a Party in accordance with
Section 13.2, the terminating Party shall have the right to require the other
Party to join with the terminating Party to cause the liquidation or winding up
of the EJV.

        Article 15.  Nature and Survival of Representations; Indemnification

    15.1.     All representations, warranties and covenants made by the Parties
in this Agreement and in any exhibit, schedule, certificate, list or other
instrument delivered in connection with the transactions contemplated hereby
shall survive the Initial Funding and any investigation at any time made or any
knowledge received by or on behalf of a Party (unless, with respect to a
material breach of a representation under Article 12, such Party had, as of the
date of this Agreement, actual knowledge of such material breach and all
necessary information to conclude that such material breach existed and, Section
15.2 will not apply to the extent of any claims in connection with such a
material breach); provided, however, that in the case of a claim for
indemnification arising under only Section 15.2(a), no Party shall have any
liability unless it receives notice on or before the first anniversary of the
date of the Initial Funding asserting a claim with respect thereto and
specifying the factual basis of such claim in reasonable detail, to the extent
known.

    15.2.     Each Party shall indemnify and hold harmless the other and the
EJV against all damage, loss, liability, diminution of value or expense,
including, without limitation, reasonable attorneys' fees and costs relating
thereto, suffered or incurred by the other Party or the EJV arising from or in
connection with:

         (a)  any misrepresentation or breach of representation or warranty by
the indemnifying Party of any representation or warranty set forth in this
Agreement or in any exhibit, schedule, certificate, list or other instrument
delivered pursuant hereto;

         (b)  any breach or nonfulfillment by the indemnifying Party of any
covenant, agreement or other obligation set forth in this Agreement or in any
exhibit, schedule, certificate, list or other instrument delivered pursuant
hereto; and

                                       20
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------

         (c)  any claim, lawsuit or proceeding that arises out of, or is
attributable or relates to, the business conducted by the indemnifying Party on
or prior to the Initial Funding.

    15.3.     Each Party shall indemnify and hold harmless the other from and
against all loss, liability, damage or expense (including reasonable attorneys'
fees) in connection with any claim by any Person for brokers' or finders' fees
or commissions or similar payments and related expenses based on any agreement
or understanding alleged to have been made with respect to the transactions
contemplated hereby by such Person with the indemnifying Party.

    15.4.     PSI shall indemnify TCG and its Affiliates and representatives
against any liabilities or expenses arising out of any claim or action
instituted by or on behalf of any shareholder of PSI with respect to the
transactions contemplated by this Agreement, except to the extent arising out of
a breach by TCG of this Agreement or due to its bad faith, gross negligence or
willful misconduct.

    15.5.     The Party seeking indemnification shall notify the Party against
whom indemnification is sought promptly of any claim by any third party coming
to its attention that may result in any liability hereunder on the other Party's
part, and the indemnifying Party shall be entitled at its own expense to conduct
the defense of any such third-party claim with counsel of its own choosing,
subject to approval by the Party seeking indemnification which approval shall
not be unreasonably withheld, and shall be entitled to participate in such
defense with counsel of its own choosing and at its own expense; provided,
however, that control of the defense will remain with counsel for the
indemnifying Party if the indemnifying Party has acknowledged unequivocally in
writing its obligation to indemnify the other Party in regard to the claims to
be defended against.  Failure to give notice as provided herein shall not
relieve the indemnifying Party of its obligations hereunder, except to the
extent that the defense of any claim is prejudiced by such failure to give
notice.  The indemnifying Party shall have the right to compromise or settle for
money damages only any claim giving rise to an obligation for indemnification
hereunder; any claim compromised or settled by the indemnified Party shall not
be subject to indemnification hereunder.

                            Article 16.   Force Majeure

    16.1.     The failure or delay of either Party hereto to perform any
obligation under this Agreement solely by reason of acts of God, acts of
government (except as otherwise enumerated herein), riots, wars, embargoes,
strikes, lockouts, accidents in transportation, port congestion or other causes
beyond its control ("Force Majeure") shall not be deemed to be a breach of this
Agreement; provided, however, that the 

                                       21
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------

Party so prevented from complying herewith shall have used reasonable 
diligence to avoid such event of Force Majeure and mitigate its effects, and 
shall continue to take all actions within its power to comply as fully as 
possible with the terms of this Agreement.

    16.2.     Except where the nature of the event shall prevent it from doing
so, the Party suffering such Force Majeure shall notify the other Party in
writing within 14 days after the occurrence of such event of Force Majeure and
shall in every instance, to the extent reasonable and lawful under the
circumstances, use its best efforts to remove or remedy such cause with all
reasonable dispatch.

                 Article 17.   Disclaimer of Agency and Partnership

    This Agreement shall not be deemed to constitute any Party the agent or
partner of the other Party, nor shall it constitute the EJV an agent of either
Party, and no Party shall have the right to bind the other.

                 Article 18.   Dispute Resolution and Governing Law

    18.1.     If any controversy or claim arises out of or relates to this
Agreement or with respect to an alleged breach of the terms hereof, the Parties
shall seek to solve the matter amicably through discussions between themselves. 
The Parties shall attempt to resolve all controversies, claims or breaches at
the operational level, and in the event a resolution cannot be reached, such
controversy, claim or breach will be referred progressively to higher levels
within each Party, to their respective boards of directors, and finally to the
chairpersons of PSI and TCG.  If the Parties fail to resolve such controversy,
claim or breach within thirty (30) days by amicable arrangement and compromise,
either Party may seek arbitration as set forth below.

    18.2.     Any controversy or claim arising out of or in relation to this
Agreement, or breach of this Agreement, shall be finally settled by arbitration
in London, England.

         (a)  The arbitration shall be conducted in the English language before
a single arbitrator in accordance with the Rules of Arbitration and Conciliation
of the International Chamber of Commerce then in effect.

         (b)  The Parties shall appoint the arbitrator by mutual agreement.  If
the parties cannot agree on the appointment of the arbitrator within thirty (30)
days after receipt of a demand for arbitration, the arbitrator shall be
appointed by the International Chamber of Commerce.

                                       22
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------
The symbol "--" indicates that a confidential portion has been omitted and 
filed separately with the Securities and Exchange Commission


         (c)  All arbitration rulings and awards shall be final and binding on
the parties and shall be enforceable in accordance with the convention on the
Recognition and Enforcement of Foreign Arbitral Awards.

         (d)  Notwithstanding any other provision of this Agreement, either
party shall be entitled to seek preliminary injunctive relief from any court of
competent jurisdiction pending the final decision or award of the arbitrators..

    18.3.     The validity, performance, construction and effect of this
Agreement shall be governed by the laws of the state of New York, without regard
to principles of conflicts of law.

                        Article 19.   Amendment; Assignment

    No modification or alteration of any term or condition of this Agreement
will be valid unless in writing signed by each Party.  This Agreement and each
and every covenant, term and condition hereof shall be binding upon and inure to
the benefit of the Parties and their successors and permitted assigns.  Subject
to Article 6, neither Party shall directly or indirectly assign its rights or
delegate its obligations hereunder without the prior written consent of the
other Party; provided, however, that PSI may assign its rights but not its
obligations hereunder to any wholly owned subsidiary of PSI reasonably
acceptable to TCG, and either Party may assign its rights and delegate its
obligations hereunder to any of its Affiliates, with the consent of the other
Party (which consent will not unreasonably be withheld) in each case so long as
such transferee agrees to be bound by the terms and conditions of this Agreement
and any related agreements, including but not limited to the License Agreement
and the Services Agreement.

                                Article 20.   Costs

    The Parties shall each pay their own legal and other costs incurred in
documenting and executing this Agreement----------------------------------------
--------------------------------------------------------------------------------
------------------  The EJV will reimburse each Party for any legal fees and
expenses incurred in preparing the documentation, registrations and formation of
the EJV. 

                           Article 21.   Confidentiality

    21.1.     Except as otherwise agreed by the Parties in writing, the Parties
agree that, at all times during the term of this Agreement and for a two-year
period following termination or expiration hereof, the Party receiving
information (the "Receiving Party") shall keep completely confidential, shall
not publish or otherwise 

                                       23
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------

disclose and shall not use, directly or indirectly, for any purpose any 
information furnished to it by the other Party (the "Disclosing Party") 
pursuant to this Agreement or otherwise relating to any transaction 
contemplated hereby, except to the extent that the Receiving Party can 
establish by competent proof that such information

         (a)  was already known to the Receiving Party, other than under an
obligation of confidentiality, at the time of disclosure by the Disclosing
Party;

         (b)  was part of the public domain at the time of its disclosure by
the Disclosing Party;

         (c)  became part of the public domain after its disclosure by the
Disclosing Party, other than through any act or omission of the Receiving Party
in breach of this Agreement;

         (d)  was disclosed to the Receiving Party by a third party who had no
obligation not to disclose such information to others; or

         (e)  has been disclosed by the Disclosing Party to any third party
without an obligation not to disclose such information to others.

    21.2.     Each Party may disclose the others Party's information to the
extent that such disclosure is reasonably necessary in filing or prosecuting
patent applications, pursuing or defending litigation, or complying with
applicable law or governmental or stock exchange regulations; provided, however,
that, if a Receiving Party intends to make any such disclosure, it shall give
reasonable advance written notice to the Disclosing Party of such intention. 
Furthermore, nothing in this Article 21 shall be construed to preclude either
Party from disclosing such information to third parties as may be necessary in
connection with the transactions contemplated by this Agreement; provided,
however, that the Receiving Party shall in each case obtain from the proposed
third-party recipient a written confidentiality undertaking containing
confidentiality obligations no less onerous than those set forth in this Article
21.
                               Article 22.   Notices

    22.1 All written notices, requests, demands and other communications under
this Agreement or in connection herewith shall be given by letter (delivered by
hand, by air courier, or by registered airmail) or by facsimile or e-mail
transmission confirmed by such a letter, and addressed to the respective Parties
as follows: 

                                       24
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------

         To TCG or the TCG Designee:
                           Chatterjee Management Company
                           888 7th Avenue, Suite 3000
                           New York, NY  10106
                           Attention:  W. James Peet
                           Internet e-mail address:  wjp@sfmny.com
                           Facsimile No.:  212-397-5554

         with copies to:   Chatterjee Management Company
                           888 7th Avenue, Suite 3000
                           New York, NY  10106
                           Attention:  Peter Hurwitz, Esq.
                           Facsimile No.:  212-262-9637
         and:              Soros Fund Management
                           888 7th Avenue, Suite 3200
                           New York, NY  10106
                           Attention:  Michael Neus, Esq.
                           Facsimile No.:  212-664-0544
         and:              Perkins Coie
                           One Bellevue Center, Suite 1800
                           411 - 108th Avenue N.E.
                           Bellevue, WA  98004-5584
                           Attention:  Craig E. Shank, Esq.
                           Internet e-mail address:  shanc@perkinscoie.com
                           Facsimile No.:  (206) 453-7350
         To PSI:           PSINet, Inc.
                           510 Huntmar Park Drive
                           Herndon, VA  22070  USA
                           Attention:  William L. Schrader
                           Internet e-mail address:  wls@psi.com
                           Facsimile No:  703-904-1608
    with a copy to:        PSINet, Inc.
                           510 Huntmar Park Drive
                           Herndon, VA  22070  USA
                           Attention:  David Kunkel, Esq.
                           Internet e-mail address:  kunkel@psi.com
                           Facsimile No.:  703-904-9527

                                       25
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------

    22.2.     A Party may change its notice information at any time by written
notice to the other Party.

                            Article 23.   Press Releases

    Each Party shall not, and shall cause their Affiliates not to, make
publicly available any press release, promotional material or similar public
statement naming or otherwise identifying the other Party or any of its
Affiliates without such other Party's prior consent, which consent will not
unreasonably be withheld.  Each Party and any of their respective Affiliates
shall provide the other Party, as early as reasonably practicable, drafts of all
press releases that include references to such other Party or any of its
Affiliates, and shall consider and use reasonable efforts to incorporate into
all such press releases any comments provided by such other Party in a
reasonably timely manner.

                              Article 24.   No Waiver

    The waiver by a Party of a breach or a failure to assert a breach by the
other Party of any covenant, obligation or provision in this Agreement
(contained or implied) does not operate as a waiver of another or continuing
breach or failure to assert a breach by the other Party of the same or any other
covenant, obligation or provision in this Agreement contained or implied.

                              Article 25.   Severance

    If any one or more of the provisions contained in this Agreement shall be
invalid, illegal or unenforceable in any respect under any applicable law, then
the validity, legality and enforceability of the remaining provisions contained
in this Agreement shall not in any way be affected or impaired, and in such
case, the parties agree to use their best efforts to achieve the purpose of the
invalid provision by a new, legally valid provision.

                             Article 26.   Counterparts

    This Agreement may be executed in two counterparts, each of which shall be
deemed an original.
                         Article 27.   Government Approval

    27.1.     TCG shall provide reasonable cooperation (e.g., furnishing
reasonable background or contact information) with the efforts of PSI or the EJV
to obtain any Government Approval.

                                       26
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------

    27.2.     TCG shall provide reasonable cooperation (e.g., furnishing
reasonable background or contact information) with the efforts of PSI and the
EJV in obtaining, after the date of the Initial Funding, any further Government
Approval of this Agreement or of any amendment hereto as required under the laws
or regulations of any jurisdiction in which the EJV shall desire to conduct
business.

                          Article 28.   Further Assurances

    Each Party shall duly execute and deliver, or cause to be duly executed and
delivered, such further instruments and do, or cause to be done, such further
acts and things, including, without limitation, the filing of such assignments,
agreements, documents and instruments, as may be necessary or as the other Party
may reasonably request in connection with this Agreement or to carry out more
effectively the provisions and purposes hereof, or to better assure and confirm
to such other Party its rights and remedies under this Agreement.

                           Article 29.   Entire Agreement

    This Agreement supersedes all previous representations, understandings or
agreements, oral or written, between the Parties with respect to the subject
matter hereof, and, together with the agreements and documents attached hereto
as exhibits, contains the entire understanding of the Parties as to the terms
and conditions of their relationship. 

                                       27
<PAGE>
                                              CONFIDENTIAL TREATMENT REQUESTED
                                              --------------------------------


    IN WITNESS WHEREOF, the Parties have caused this Agreement to be executed
by a representative thereunto duly authorized as of the date first set forth
above.

PSINET INC.


By  /s/ David N. Kunkel
  -----------------------------
    Name:  David Kunkel
    Title:  Senior Vice President and General Counsel

CHATTERJEE MANAGEMENT COMPANY

By  /s/ James Peet
  -----------------------------
    Name:  James Peet
    Title:  Vice President

                                       28
<PAGE>

Exhibits to the Joint Venture Agreement have been omitted.

The following is a list of the omitted Exhibits which the Company agrees to
furnish supplementally to the Commission upon request:
    
    Exhibits:
    
         Exhibit A      Decisions Requiring the Consent of the TCG Directors or
                        the TCG Designee
         Exhibit B      Terms of Services Agreement 
         Exhibit C      Terms of License Agreement
         Exhibit D      Form of Registration Rights Agreement