FIFTH AMENDMENT TO 1997 REVOLVING CREDIT AGREEMENT


         THIS FIFTH  AMENDMENT to 1997  REVOLVING  CREDIT  AGREEMENT (the "Fifth
Amendment")  is  intended  to  amend  the  terms of the  1997  Revolving  Credit
Agreement  (the  "Agreement")  dated as of  February  26,  1997,  as  previously
amended,  among DATA TRANSMISSION  NETWORK  CORPORATION;  FIRST NATIONAL BANK OF
OMAHA;  FIRST NATIONAL  BANK,  WAHOO,  NEBRASKA;  NBD BANK,  N.A.;  NORWEST BANK
NEBRASKA, N.A.; THE SUMITOMO BANK, LIMITED;  MERCANTILE BANK OF ST. LOUIS, N.A.;
U.S.  BANK,  NATIONAL  ASSOCIATION  (formerly  known  as  First  Bank,  National
Association);  BANK OF MONTREAL;  LASALLE NATIONAL BANK; and  NATIONSBANK,  N.A.
(successor  to  THE  BOATMEN'S  NATIONAL  BANK  OF ST.  LOUIS).  All  terms  and
conditions  of the  Agreement  shall  remain in full force and effect  except as
expressly  amended herein.  All capitalized terms herein shall have the meanings
prescribed in the Agreement. The Agreement shall be amended as follows:

         1.    The  definitions  in Article I of the  Agreement  are  amended as
               follows:
   
               Revolving Credit Notes: The following  sentence is added to the
                                       end of such definition:
                                               
                                        Solely for  purposes  of Section  7.2 of
                                        this Agreement and any reference to such
                                        Section 7.2, the Revolving  Credit Notes
                                        shall  include the amounts,  if any, due
                                        to  (a)  FNB-O   and/or  the   Revolving
                                        Lenders   under  the  Letter  of  Credit
                                        Facility,  and (b) Norwest in connection
                                        with the Norwest Letters of Credit.


         2.    The following  shall be added to the  definitions in Article I of
               the Agreement:

               Base Revolving Credit
                                        Facility:   The  amount   specified   in
                                        Section  2.1 of  this  Agreement,  which
                                        shall  include  the  aggregate   amounts
                                        which   may  be   available   under  the
                                        Revolving  Credit  Notes and the  Lender
                                        Letter of Credit Facility.

               FNB-O Letter of Credit
                                        Facility:   An  amount   not  to  exceed
                                        $500,000  at any time  which  FNB-O  may
                                        elect in its  discretion  to  provide to
                                        the  Borrower  and  one or  more  of its
                                        Subsidiaries   under  Section  2.11  (a)
                                        hereof.

                                       1
                                    - 489 -
<PAGE>

                                            FNB-O Letter(s) of  Credit:Letter(s)
                                        of Credit  issued under the FNB-O Letter
                                        of Credit Facility.

               Lender Letter  of Credit
                                            Facility:   The   letter  of  credit
                                        facility  provided  for in Section  2.11
                                        (b) hereof.


                                            Lender    Letter(s)    of    Credit:
                                        Letter(s)  of  Credit  issued  under the
                                        Lender  Letter of Credit  Facility,  the
                                        outstanding  face  amount of which shall
                                        not exceed $1,000,000 at any time.

                                            Letter of Credit Facility:Either the
                                        FNB-O or the  Lender  Letter  of  Credit
                                        Facility or, if the context so requires,
                                        both such letter of credit facilities.

                                            Letter of Credit Fees: The Letter of
                                        Credit Fees  specified  in Section  2.11
                                        (d) of the Agreement.


                                            Letter(s)  of  Credit:   Either  the
                                        FNB-O  Letter(s) of Credit or the Lender
                                        Letter(s)  of Credit,  or if the context
                                        so requires,  both such types of letters
                                        of credit.

                                            Norwest    Letters   of   Credit:The
                                        letters of credit  indicated below which
                                        were  issued by Norwest  for the account
                                        of Kavouras,  Inc.: (a) letter of credit
                                        no.   S405712,    in   the   amount   of
                                        $132,954.00  with an expiration  date of
                                        August  15,  1998;  and  (b)  letter  of
                                        credit  no.  S405444,  in the  amount of
                                        $130,949.00  with an expiration  date of
                                        July 30, 1999; but not letters of credit
                                        issued in exchange,  renewal,  extension
                                        or substitution of such original letters
                                        of credit.
 
                                        2
                                     - 490 -
<PAGE>

         3.    The following shall be added as Section 2.11 of the Agreement:

               2.11 Letter of Credit  Facilities.  In order to  accommodate  the
needs of the  Borrower  or one or more of its  Subsidiaries,  from  time to time
FNB-O on its own  behalf  may,  or FNB-O as the Agent of the  Revolving  Lenders
under this Agreement  shall,  upon application of the Borrower and, if requested
by FNB-O the applicable  Subsidiary,  issue letters of credit on the terms,  and
upon satisfaction of the conditions, specified below:

                    (a)  FNB-O  Letter of  Credit  Facility.  FNB-O may elect to
               issue letters of credit solely on its own behalf ("FNB-O  Letters
               of Credit");  provided,  however, that at the time of issuance of
               such FNB-O Letters of Credit,  the aggregate  amount available to
               be drawn on Letters of Credit issued and  outstanding  under this
               FNB-O Letter of Credit  Facility shall not exceed  $500,000.  The
               issuance  of FNB-O  Letters  of  Credit  shall not cause the Base
               Revolving Credit Facility to be reduced.

                    (b) Lender Letter of Credit Facility.  Whenever FNB-O elects
               not to issue an FNB-O  Letter of Credit or the  aggregate  amount
               available to be drawn on FNB-O Letters of Credit exceeds, or upon
               the issuance of a new Letter of Credit will exceed, $500,000, the
               Agent on behalf of the Revolving Lenders shall issue from time to
               time  for  the  account  of the  Borrower  or one or  more of its
               Subsidiaries letters of credit in the name of First National Bank
               of Omaha but which are  designated  as Lender  Letters  of Credit
               (the "Lender Letters of Credit");  provided,  however,  the Agent
               shall  have no  obligation  to issue  any such  Lender  Letter of
               Credit unless at such time the Borrower  meets all the conditions
               for an Advance  under the Base  Revolving  Credit  Facility  and,
               after such issuance,  the aggregate face amount of Lender Letters
               of Credit  outstanding  will not exceed  $1,000,000  and will not
               exceed the then  available  Base Revolving  Credit  Facility,  as
               reduced  by the  outstanding  principal  amount of the  Converted
               Notes and the Revolving  Credit Notes, as more  specifically  set
               forth in this Agreement. The Revolving Lenders shall be obligated
               to  fund  pro  rata  according  to  their   respective  pro  rata
               percentages  shown in Section 2.1 of this  Agreement any draws on
               such Lender  Letters of Credit and shall be entitled to share pro
               rata in the  Letter  of  Credit  Fees and  reimbursement  amounts
               received in connection  with such Lender  Letters of Credit.  The
               sum of (i)  amounts  drawn  under such  Lender  Letters of Credit
               which  have not been  reimbursed  by the  Borrower,  and (ii) the
               amounts available to be drawn under outstanding Lender Letters of
               Credit shall operate to reduce the Base Revolving Credit Facility
               by such sum.

                    (c) Letter of Credit Documents,  Fees. Prior to the issuance
               by FNB-O of any Letters of Credit, the Borrower and, if requested
               by FNB-O, the applicable Subsidiary, shall execute and deliver to


                                       3
                                    - 491 -
<PAGE>

               FNB-O an application and continuing  letter of credit  agreement,
               such  agreements to be in the forms attached  hereto as Exhibit C
               to this Fifth  Amendment,  as such forms may be amended from time
               to time for  general  use in  connection  with  letters of credit
               issued by FNB-O.

                    (d) Letter of Credit Fees. In addition to all costs incurred
               by FNB-O in the issuance and enforcement of the Letters of Credit
               which are to be reimbursed by the Borrower in accordance with the
               application and continuing letter of credit agreement executed in
               connection with each Letter of Credit,  the Borrower shall pay to
               FNB-O (on its own  behalf as to FNB-O  Letters  of Credit  and as
               Agent as to Lender Letters of Credit) a letter of credit fee (the
               "Letter of Credit  Fee") equal to one  percent  (1%) per annum of
               the undrawn amount of such Letter of Credit,  such fee to be paid
               quarterly  in arrears  based on the  average  amount  outstanding
               during such quarter; provided,  however, that at any time that an
               Event  of  Default  has  occurred  and is  continuing  under  the
               Agreement,  such fee  shall be  equal  to five  percent  (5%) per
               annum).  Interest  shall accrue on amounts drawn under any Letter
               of Credit,  until such amount is reimbursed,  at the then current
               rate for amounts  outstanding  under the Revolving  Note and, for
               any  period  that such draw  remains  unreimbursed  more than two
               Business  Days after such draw, at the Default Rate. In addition,
               the Borrower shall pay such other  administrative fees, including
               a fee for opening the Letter of Credit,  as are agreed in writing
               between FNB-O and the Borrower. Amounts received by the Agent for
               opening a Lender Letter of Credit or as administrative fees other
               than the Letter of Credit  remain the  property  of the Agent and
               shall not be shared pro rata with the Revolving Lenders.

                    (e) Security.  Amounts due in connection with the Letters of
               Credit  and the  Norwest  Letters  of Credit  are  secured by the
               Collateral  pledged under the Security Agreement and any security
               agreement  given by a  Subsidiary  in favor  of the  Lenders.  In
               addition,  the Agent  shall have the right to require  additional
               collateral,  including  cash  collateral  equal  to  100%  of the
               aggregate of the amounts  available to be drawn under the Letters
               of Credit,  upon the  occurrence of an Event of Default under the
               Agreement.

         4. The Drawing Certificate attached to the Agreement as Exhibit B shall
be amended as shown on Exhibit B to this Fifth Amendment.

         5. This Fifth Amendment  shall not affect and there remain  outstanding
from the  Borrower to the Banks,  the  Existing  Term Notes and the Related Bank
Debt.

         6. This Fifth  Amendment  may be executed in several  counterparts  and
such counterparts together shall constitute one and the same instrument.

         Except as expressly  agreed  herein,  all terms of the Agreement  shall
remain in full force and effect.



                                       4
                                    - 492 -
<PAGE>

         IN WITNESS WHEREOF,  the undersigned have executed this FIFTH AMENDMENT
TO 1997 REVOLVING CREDIT AGREEMENT dated as of July 10, 1998.

                                                   DATA TRANSMISSION NETWORK
                                                   CORPORATION

                                                   By /s/ Brian L. Larson
                                                      -----------------------
                                                     Title: Vice President, CFO
                                                       and Secretary


                                                   FIRST NATIONAL BANK OF OMAHA



                                                   By /s/ James P. Bonham
                                                       ------------------------
                                                    Title: Vice President



NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower


                                       5
                                    - 493 -
<PAGE>





                                                   THE SUMITOMO BANK, LIMITED


                                                   
                                                   By /s/Brian M. Smith
                                                       ------------------------
                                                    Title: Senior Vice President







NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower


                                       6
                                    - 494 -
<PAGE>

                                                   FIRST NATIONAL BANK, WAHOO,
                                                   NEBRASKA



                                                   By/s/ Elizabeth E. Rezac
                                                     --------------------------
                                                    Title: Second Vice President




NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower


                                       7
                                     -495 -
<PAGE>


                                                   NBD BANK


                                                   By /s/ Nathan L. Bloch
                                                      ------------------------
                                                      Title:First Vice President




NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower


                                       8
                                    - 496 -
<PAGE>


                                                   NORWEST BANK NEBRASKA, N.A.




                                            By /s/ Kevin D. Munro
                                             ----------------------------------
                                             Title:Vice President




NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower


                                       9
                                    - 497 -
<PAGE>





                                            LASALLE NATIONAL BANK, a national
                                            banking association




                                            By/s/ Tom Harmon
                                              --------------------------------
                                             Title:Assistant Vice President




NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower


                                       10
                                    - 498 -
<PAGE>

                                                   MERCANTILE BANK OF
                                                   ST. LOUIS, N.A.


                                            By/s/ Joseph L. Sooter, Jr.
                                              --------------------------------
                                             Title:Vice President






NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower



                                       11
                                    - 499 -
<PAGE>
                                                   U.S. BANK, NATIONAL
                                                   ASSOCIATION


                                            By /s/ Beth Morgan
                                               -------------------------------
                                             Title: Vice President






NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower



                                       12
                                    - 500 -
<PAGE>




                                                   NATIONSBANK, N.A.



                                            By/s/ Michael F. Murphy
                                              --------------------------------
                                             Title: Vice President






NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                                   INITIALED:


                                                   Borrower



                                       13
                                    - 501 -
<PAGE>




                                                   BANK OF MONTREAL,
                                                   Chicago Branch




                                            By/s/ Karen Klapper
                                              -------------------------------
                                             Title: Director






NOTICE: A credit  agreement must be in writing to be enforceable  under Nebraska
law. To protect you and us from any  misunderstandings  or disappointments,  any
contract,  promise,  undertaking,  or offer to forebear repayment of money or to
make any other financial  accommodation in connection with this loan of money or
grant or extension of credit,  or any amendment of,  cancellation of, waiver of,
or  substitution  for any or all of the terms or provisions of any instrument or
document executed in connection with this loan of money or grant or extension of
credit, must be in writing to be effective.

                                            INITIALED:


                                            Borrower


                                       14
                                    - 502 -
<PAGE>

                                    EXHIBIT B



                       TO 1997 REVOLVING CREDIT AGREEMENT
                                      among
                           DATA TRANSMISSION NETWORK,
                          FIRST NATIONAL BANK OF OMAHA,
                      FIRST NATIONAL BANK, WAHOO, NEBRASKA,
                                    NBD BANK,
                          NORWEST BANK NEBRASKA, N.A.,
                               NATIONSBANK, N.A.,
                       MERCANTILE BANK OF ST. LOUIS, N.A.,
                        U.S. BANK, NATIONAL ASSOCIATION,
                                BANK OF MONTREAL
                                       AND
                             LASALLE NATIONAL BANK,




                               DRAWING CERTIFICATE



                                       15
                                    - 503 -
<PAGE>


                               DRAWING CERTIFICATE
                      DATA TRANSMISSION NETWORK CORPORATION

To induce  the  First  National  Bank of  Omaha,  First  National  Bank,  Wahoo,
Nebraska,  NBD  Bank,  Norwest  Bank  Nebraska,  N.A.,  LaSalle  National  Bank,
Nationsbank,  N.A.,  Mercantile  Bank of St. Louis,  N.A.,  U.S. Bank,  National
Association,  and Bank of Montreal (the "Revolving  Lenders") to make an advance
under the 1997 Revolving Credit Agreement (the "Agreement") dated as of February
26, 1997,  between the undersigned (the  "Borrower"),  Nationsbank,  N.A. as the
successor in interest to The Boatmen's National Bank of St. Louis  ("Boatmen's),
and the Revolving  Lenders (as to Boatmen's and the Revolving  Lenders together,
(the  "Banks"),  the Borrower  hereby  certifies to the Banks that its Operating
Cash Flow (as defined in the Agreement) as represented below is true and correct
and that there is no default under the aforementioned Agreement, or on any other
liability of the Borrower to the Banks.

All information as of:  Date

a)  Maximum Revolving Credit Facility                            $

b)  Principal on Converted Notes                                 $___________

c)  Acquisition Notes, Existing Term Notes,
    and Related Bank Debt Outstanding                            $

d)  Principal on Revolving Credit Notes                          $

e)  Unreimbursed amounts drawn under Lender Letters
    of Credit                                                    $

f)  Amount available to be drawn under outstanding
    Lender Letters of Credit

g)  ADVANCE REQUEST ( not to exceed line a - line  b
    -  line d -  line e - line f)                                $

h)  Total Proposed Bank Debt
    (line b + line c + line d + line e + line f + line g)        $

i)  Most recent month's operating cash flow                      $

j)  Prior month's operating cash flow                            $

k)  Operating Cash Flow
    (average of line i and line j)                               $

l)  Total Indebtedness                                           $
m)  Leverage Ratio (line l divided by  line m), not to exceed
    36                                                           $

Name of Borrower:  Data Transmission Network Corporation
Signature:
Title:



                                       16
                                    - 504 -


<PAGE>



                                    EXHIBIT C

                       TO 1997 REVOLVING CREDIT AGREEMENT
                                      among
                           DATA TRANSMISSION NETWORK,
                          FIRST NATIONAL BANK OF OMAHA,
                      FIRST NATIONAL BANK, WAHOO, NEBRASKA,
                                    NBD BANK,
                          NORWEST BANK NEBRASKA, N.A.,
                               NATIONSBANK, N.A.,
                       MERCANTILE BANK OF ST. LOUIS, N.A.,
                        U.S. BANK, NATIONAL ASSOCIATION,
                                BANK OF MONTREAL
                                       AND
                             LASALLE NATIONAL BANK,




         FORMS OF APPLICATION AND CONTINUING LETTER OF CREDIT AGREEMENT



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                                    - 505 -