<PAGE>
                                                                   Exhibit 10.19



                              FIRST SUPPLEMENT TO
              SECOND AMENDED AND RESTATED REGISTRATION AGREEMENT
              --------------------------------------------------

          THIS FIRST SUPPLEMENT TO SECOND AMENDED AND RESTATED REGISTRATION
AGREEMENT (this "Agreement") is made as of _____________, 2000, by and among
CompleTel Europe N.V. (the "Company") and the parties to the Second Amended
Agreement (as defined below) (including CompleTel LLC ("CompleTel LLC"), Madison
Dearborn Capital Partners II, L.P. ("MDCP"), DeGeorge Holdings Limited
Partnership ("DeGeorge Holdings"), Meritage Private Equity Fund, L.P.
("Meritage"), James C. Allen ("Allen"), Royce J. Holland ("Holland"), George T.
Laub ("Laub"), Reed E. Hundt ("Hundt"), Emile Karafiol ("Karafiol"), William S.
Kirsch ("Kirsch"), Northwestern University ("Northwestern"), Silver Cross
Investors LLC ("SCI"), Dovey Company LLC ("Dovey LLC"), William H. Pearson
("Pearson"), Haj LLC ("Pearson LLC #2"), Clevenger Company LLC ("Clevenger
LLC"), and David E. Lacey ("Lacey"), and the other holders of Registrable
Securities listed on the signature pages attached to the Second Amended
Agreement (as defined below)).  MDCP, DeGeorge Holdings, Meritage, Allen,
Holland, Laub, Hundt, Karafiol, Kirsch, Northwestern, and SCI are referred to
herein collectively as the "Investors" and individually as an "Investor."
Capitalized terms used but not otherwise defined herein have the meanings set
forth in paragraph 8 hereof.

          As of May 18, 1998, the Company and MDCP, Lawrence F. DeGeorge
("DeGeorge"), James E. Dovey ("Dovey"), Pearson, and Richard N. Clevenger
("Clevenger") entered into a Registration Agreement (the "Prior Agreement").  As
of January 28, 1999, the parties (other than the Company, Meritage, Pearson LLC
#2, Karafiol, Kirsch, Northwestern, and SCI) entered into a First Amended and
Restated Registration Agreement (the "First Amended Agreement"), amending and
restating the Prior Agreement in its entirety.  As of November 23, 1999, the
parties (other than the Company) entered into a Second Amended and Restated
Registration Agreement (the "Second Amended Agreement"), amending and restating
the First Amended Agreement in its entirety.

          The Company has filed a registration statement on Form F-1 with the
Securities and Exchange Commission covering the Company's proposed issuance of
its ordinary shares to the public (the "Proposed IPO").  The parties (other than
the Company) have entered into an Omnibus Amendment, to which this Agreement is
an exhibit (the "Omnibus Amendment"), in order to amend various transaction
documents described therein (including the Second Amended Agreement) effective
upon the consummation of the Proposed IPO.  Pursuant to the terms and subject to
the conditions set forth in the Omnibus Amendment, the parties hereto desire
that, effective upon the consummation of the Proposed IPO, the Second Amended
Agreement will be amended and supplemented with the provisions set forth in this
Agreement, the provisions hereof will be incorporated into and become a part of
the Second Amended Agreement, and the provisions of this Agreement will be
valid, binding, and effective against the Company and each of the parties to the
Second Amended Agreement pursuant to the amendment provisions of Section 9(d)
thereof.
<PAGE>

          NOW, THEREFORE, in consideration of the mutual promises made herein
and other good and valuable consideration, the receipt and sufficiency of which
are hereby acknowledged, the parties hereto, intending to be legally bound,
agree as follows:

          1.   Demand Registrations.
               --------------------

          (a) Requests for Registration.  At any time after the date hereof, (i)
the holders of a majority of the MDCP Registrable Securities then outstanding
may request up to two registrations under the Securities Act of all or any
portion of their Registrable Securities on Form S-1 or any similar long-form
registration (each, a "Long-Form Registration"), (ii) the holders of a majority
of the DeGeorge Registrable Securities then outstanding may request one Long-
Form Registration, (iii) the holders of at least 10% of the Purchaser
Registrable Securities then outstanding may request registration under the
Securities Act of all or any portion of their Registrable Securities on Form S-3
or any similar short-form registration ("Short-Form Registrations") if
available, and (iv) the holders of a majority of the Meritage Registrable
Securities then outstanding may request one Short-Form Registration, if
available; provided that the aggregate offering value of the Registrable
Securities requested to be registered in any registration under this paragraph
1(a) (any "Demand Registration") must equal at least $15 million in any Long-
Form Registration, and at least $5 million in any Short-Form Registration; and
provided further that the right of the holders of Meritage Registrable
Securities under clause (iv) above will terminate at such time as Meritage and
its affiliates cease to hold in the aggregate at least 50% of the Meritage
Registrable Securities held by Meritage on the date hereof.

          All requests for Demand Registrations shall be made by giving written
notice to the Company (the "Demand Notice").  Each Demand Notice shall specify
the approximate number of Registrable Securities requested to be registered and
the anticipated per share price range for such offering.  Within ten days after
receipt of any Demand Notice, the Company shall give written notice of such
requested registration to all other holders of Registrable Securities and,
subject to the provisions of paragraph 1(d) below, shall include in such
registration all Registrable Securities with respect to which the Company has
received written requests for inclusion therein within 15 days after the receipt
of the Company's notice.

          (b) Expenses; Withdrawal.  The Company shall pay all Registration
Expenses of all holders of Registrable Securities in all Demand Registrations.
A registration shall not count as one of the permitted Long-Form Registrations
(or, in the case of a Short-Form Registration requested by the holders of
Meritage Registrable Securities, as the one permitted Short-Form Registration
under Section 1(a)(iv)) until both (i) it has become effective and (ii) the
holders of Registrable Securities initially requesting such registration are
able to register and sell at least 90% of the Registrable Securities requested
to be included in such registration; provided that the Company shall in any
event pay all Registration Expenses in connection with any registration
initiated as a Demand Registration whether or not it has become effective and
whether or not such registration has counted as one of the permitted Long-Form
Registrations (or, if applicable, as the one permitted Short-Form Registration
under Section 1(a)(iv)).  All Long-Form Registrations shall be underwritten
registrations

                                      -2-
<PAGE>

unless otherwise requested by the holders of a majority of the Registrable
Securities included in the applicable Long-Form Registration.

          (c) Short-Form Registrations.  Demand Registrations shall be Short-
Form Registrations whenever the Company is permitted to use any applicable short
form.  After the Company has become subject to the reporting requirements of the
Securities Exchange Act, the Company shall use its best efforts to make Short-
Form Registrations on Form S-3 (or any successor form) available for the sale of
Registrable Securities.

          (d) Priority on Demand Registrations.  The Company shall not include
in any Demand Registration any securities which are not Registrable Securities
without the prior written consent of the holders of a majority of the
Registrable Securities included in such registration.  If a Demand Registration
is an underwritten offering and the managing underwriters advise the Company in
writing that in their opinion the number of Registrable Securities and, if
permitted hereunder, other securities requested to be included in such offering
exceeds the number of Registrable Securities and other securities, if any, which
can be sold in an orderly manner in such offering within a price range
acceptable to the holders of a majority of the Registrable Securities initially
requesting registration, the Company shall include in such registration the
number which can be so sold in the following order of priorities:  (i) first,
the Purchaser Registrable Securities requested to be included in such
registration, pro rata among the holders of such Purchaser Registrable
Securities on the basis of the number of shares owned by each such holder, (ii)
second, the other Registrable Securities requested to be included in such
registration, pro rata among the holders of such Registrable Securities on the
basis of the number of shares owned by each such holder, and (ii) third, other
securities requested to be included in such registration.

          (e) Restrictions on Long-Form Registrations.  The Company shall not be
obligated to effect any Demand Registration which is a Long-Form Registration
within 180 days after the effective date of a previous Demand Registration which
was a Long-Form Registration or a previous registration in which the holders of
Registrable Securities were given piggyback rights pursuant to paragraph 2 and
in which such holders were able to register and sell at least 90% of the number
of Registrable Securities requested to be included therein.  The Company may
preempt any request for a Demand Registration in order to effect an underwritten
primary registration on behalf of the Company, provided that (i) such preempting
underwritten primary registration must become effective within 90 days after the
date such preempted Demand Registration is requested, (ii) the holders of
Registrable Securities initially requesting the preempted Demand Registration
must have piggyback rights pursuant to paragraph 2 with respect to the
preempting primary registration and must be able to register and sell pursuant
to such piggyback rights in such primary registration at least 90% of the
Registrable Securities initially requested to be included in the preempted
Demand Registration, (iii) the Company shall pay all Registration Expenses in
connection with any such preempting primary registration, and (iv) the preempted
Demand Registration shall not count as one of the permitted Demand Registrations
hereunder. The Company may preempt a Demand Registration hereunder only once in
any 12-month period.  The Company may postpone for up to 180 days the filing or
the effectiveness of a registration statement for a Demand Registration if the


                                      -3-
<PAGE>

Company's board of directors determines in its reasonable good faith judgment
that such Demand Registration would reasonably be expected to have a material
adverse effect on any proposal or plan by the Company or any of its direct or
indirect subsidiaries to engage in any acquisition of assets (other than in the
ordinary course of business) or any merger, consolidation, tender offer,
reorganization or similar transaction; provided that in such event, the holders
of Registrable Securities initially requesting such Demand Registration shall be
entitled to withdraw such request and, if such request is withdrawn, such Demand
Registration shall not count as one of the permitted Demand Registrations
hereunder and the Company shall pay all Registration Expenses in connection with
such withdrawn registration. The Company may delay a Demand Registration
hereunder only once in any twelve-month period.

          (f) Selection of Underwriters.  Subject to the approval rights granted
to the holders of Purchaser Registrable Securities under the Equity Purchase
Agreement, the Board shall select the investment banker(s) and manager(s) to
administer the offering.

          (g) Other Registration Rights.  Except as provided in this Agreement,
the Company shall not grant to any Persons the right to request the Company to
register any equity securities of the Company, or any securities convertible or
exchangeable into or exercisable for such securities, without the prior written
consent of the holders of a majority of the Purchaser Registrable Securities
(or, if none, the Registrable Securities) then outstanding; provided that the
Company may grant rights to other Persons to participate in Piggyback
Registrations so long as such rights are subordinate to the rights of the
holders of Registrable Securities with respect to such Piggyback Registrations;
and provided further that the Company may grant rights to other Persons to
request registrations so long as the holders of Registrable Securities are
entitled to participate in any such registrations with such Persons pro rata on
the basis of the number of shares owned by each such holder.

          2.   Piggyback Registrations.
               -----------------------

          (a) Right to Piggyback.  Whenever the Company proposes to register any
of its securities under the Securities Act (other than pursuant to a Demand
Registration) and the registration form to be used may be used for the
registration of Registrable Securities (a "Piggyback Registration"), the Company
shall give prompt written notice (in any event within three business days after
its receipt of notice of any exercise of demand registration rights other than
under this Agreement) to all holders of Registrable Securities of its intention
to effect such a registration and shall, subject to the provisions of paragraph
2(c) below, include in such registration all Registrable Securities with respect
to which the Company has received written requests for inclusion therein within
20 days after the receipt of the Company's notice.

          (b) Piggyback Expenses.  The Registration Expenses of the holders of
Registrable Securities shall be paid by the Company in all Piggyback
Registrations.

                                      -4-
<PAGE>

          (c) Priority on Primary Registrations.  If a Piggyback Registration is
an underwritten primary registration on behalf of the Company, and the managing
underwriters advise the Company in writing that in their opinion the number of
securities requested to be included in such registration exceeds the number
which can be sold in an orderly manner in such offering within a price range
acceptable to the Company, the Company shall include in such registration (i)
first, the securities the Company proposes to sell, (ii) second, the Purchaser
Registrable Securities requested to be included in such registration, pro rata
among the holders of such Purchaser Registrable Securities on the basis of the
number of shares owned by each such holder, (iii) third, the other Registrable
Securities requested to be included in such registration, pro rata among the
holders of such Registrable Securities on the basis of the number of shares
owned by each such holder, and (iv) fourth, other securities requested to be
included in such registration.

          (d) Priority on Secondary Registrations.  If a Piggyback Registration
is an underwritten secondary registration on behalf of holders of the Company's
securities, and the managing underwriters advise the Company in writing that in
their opinion the number of securities requested to be included in such
registration exceeds the number which can be sold in an orderly manner in such
offering within a price range acceptable to the holders initially requesting
such registration, the Company shall include in such registration (i) first, the
securities requested to be included therein by the holders requesting such
registration and the Registrable Securities requested to be included in such
registration, pro rata among the holders of any such securities on the basis of
the number of securities so requested to be included therein owned by each such
holder, and (ii) second, other securities requested to be included in such
registration.

          (e) Selection of Underwriters.  If any Piggyback Registration is an
underwritten offering, subject to the approval rights granted to the holders of
Purchaser Registrable Securities under the Equity Purchase Agreement, the Board
shall select the investment banker(s) and manager(s) to administer the offering.

          (f) Other Registrations.  If the Company has previously filed a
registration statement with respect to Registrable Securities pursuant to
paragraph 1 or pursuant to this paragraph 2, and if such previous registration
has not been withdrawn or abandoned, the Company shall not file or cause to be
effected any other registration of any of its equity securities or securities
convert  ible or exchangeable into or exercisable for its equity securities
under the Securities Act (except on Form S-8 or any successor form), whether on
its own behalf or at the request of any holder or holders of such securities,
until a period of at least 180 days has elapsed from the effective date of such
previous registration.

          3.   Holdback Agreements.
               -------------------

          (a) Holders of Registrable Securities.  Each holder of Registrable
Securities shall not effect any public sale or distribution (including sales
pursuant to Rule 144) of equity securities of the Company, or any securities
convertible into or exchangeable or exercisable for such securities, during the
seven days prior to and the 180-day period beginning on the effective date of
any

                                      -5-
<PAGE>

underwritten Demand Registration or any underwritten Piggyback Registration
in which Registrable Securities are included (in each case, except as part of
such underwritten registration), unless in each case the underwriters managing
the registered public offering otherwise agree.

          (b) The Company.  The Company (i) shall not effect any public sale or
distribution of its equity securities, or any securities convertible into or
exchangeable or exercisable for such securities, during the seven days prior to
and during the 180-day period beginning on the effective date of any
underwritten Demand Registration or any underwritten Piggyback Registration
(except as part of such underwritten registration or pursuant to registrations
on Form S-8 or any successor form), unless the underwriters managing the
registered public offering otherwise agree, and (ii) shall cause each holder of
its Common Stock, or any securities convertible into or exchange  able or
exercisable for Common Stock, purchased from the Company at any time after the
date of this Agreement (other than in a registered public offering or pursuant
to Rule 144) to agree not to effect any public sale or distribution (including
sales pursuant to Rule 144) of any such securities during such period (except as
part of such underwritten registration, if otherwise permitted), unless the
underwriters managing the registered public offering otherwise agree.

          4.  Registration Procedures.  Whenever the holders of Registrable
Securities have requested that any Registrable Securities be registered pursuant
to this Agreement, the Company shall use its best efforts to effect the
registration and the sale of such Registrable Securities in accordance with the
intended method of disposition thereof, and pursuant thereto the Company shall
as expeditiously as possible:

          (a) prepare and file with the Securities and Exchange Commission a
registration statement with respect to such Registrable Securities and use its
best efforts to cause such registration statement to become effective (provided
that before filing a registration statement or prospectus or any amendments or
supplements thereto, the Company shall furnish to the counsel selected by the
holders of a majority of the Registrable Securities covered by such registration
statement copies of all such documents proposed to be filed, which documents
shall be subject to the review and comment of such counsel);

          (b) notify each holder of Registrable Securities of the effectiveness
of each registration statement filed hereunder and prepare and file with the
Securities and Exchange Commission such amendments and supplements to such
registration statement and the prospectus used in connection therewith as may be
necessary to keep such registration statement effective for a period of not less
than 180 days and comply with the provisions of the Securities Act with respect
to the disposition of all securities covered by such registration statement
during such period in accordance with the intended methods of disposition by the
sellers thereof set forth in such registration statement;

          (c) furnish to each seller of Registrable Securities such number of
copies of such registration statement, each amendment and supplement thereto,
the prospectus included in such registration statement (including each
preliminary prospectus) and such other documents as such

                                      -6-
<PAGE>

seller may reasonably request in order to facilitate the disposition of the
Registrable Securities owned by such seller;

          (d) use its best efforts to register or qualify such Registrable
Securities under such other securities or blue sky laws of such jurisdictions as
any seller reasonably requests and do any and all other acts and things which
may be reasonably necessary or advisable to enable such seller to consummate the
disposition in such jurisdictions of the Registrable Securities owned by such
seller (provided that the Company shall not be required to (i) qualify generally
to do business in any jurisdiction where it would not otherwise be required to
qualify but for this subparagraph, (ii) subject itself to taxation in any such
jurisdiction or (iii) consent to general service of process in any such
jurisdiction);

          (e) notify each seller of such Registrable Securities, at any time
when a prospectus relating thereto is required to be delivered under the
Securities Act, of the happening of any event as a result of which the
prospectus included in such registration statement contains an untrue statement
of a material fact or omits any fact necessary to make the statements therein
not misleading, and, at the request of any such seller, the Company shall
prepare a supplement or amendment to such prospectus so that, as thereafter
delivered to the purchasers of such Registrable Securities, such prospectus
shall not contain an untrue statement of a material fact or omit to state any
fact necessary to make the statements therein not misleading;

          (f) cause all such Registrable Securities to be listed on each
securities exchange on which similar securities issued by the Company are then
listed and, if not so listed, to be listed on the Nasdaq and, if listed on the
Nasdaq, use its best efforts to secure designation of all such Registrable
Securities covered by such registration statement as a Nasdaq "national market
system security" within the meaning of Rule 11Aa2-1 of the Securities and
Exchange Commission or, failing that, to secure Nasdaq authorization for such
Registrable Securities and, without limiting the generality of the foregoing, to
arrange for at least two market makers to register as such with respect to such
Registrable Securities with the National Association of Securities Dealers (the
"NASD");

          (g) provide a transfer agent and registrar for all such Registrable
Securities not later than the effective date of such registration statement;

          (h) enter into such customary agreements (including underwriting
agreements in customary form) and take all such other actions as the holders of
a majority of the Registrable Securities being sold or the underwriters, if any,
reasonably request in order to expedite or facilitate the disposition of such
Registrable Securities (including effecting a stock split, a combination of
shares, or other recapitalization);

          (i) make available for inspection by any seller of Registrable
Securities, any underwriter participating in any disposition pursuant to such
registration statement and any attorney, accountant or other agent retained by
any such seller or underwriter, all financial and other records, pertinent
corporate documents and properties of the Company, and cause the Company's
officers,

                                      -7-
<PAGE>

directors, employees and independent accountants to supply all information
reasonably requested by any such seller, underwriter, attorney, accountant or
agent in connection with such registration statement;

          (j) otherwise use its best efforts to comply with all applicable rules
and regulations of the Securities and Exchange Commission, and make available to
its security holders, as soon as reasonably practicable, an earnings statement
covering the period of at least twelve months beginning with the first day of
the Company's first full calendar quarter after the effective date of the
registration statement, which earnings statement shall satisfy the provisions of
Section 11(a) of the Securities Act and Rule 158 thereunder;

          (k) permit any holder of Registrable Securities which holder, in its
sole and exclusive judgment, might be deemed to be an underwriter or a
controlling person of the Company, to participate in the preparation of such
registration or comparable statement and to require the insertion therein of
material, furnished to the Company in writing, which in the reasonable judgment
of such holder and its counsel should be included;

          (l) in the event of the issuance of any stop order suspending the
effectiveness of a registration statement, or of any order suspending or
preventing the use of any related prospectus or suspending the qualification of
any Common Stock included in such registration statement for sale in any
jurisdiction, the Company shall use its best efforts promptly to obtain the
withdrawal of such order;

          (m) obtain a cold comfort letter from the Company's independent public
accountants in customary form and covering the matters customarily covered by
cold comfort letters as the holders of a majority of the Registrable Securities
being sold reasonably request; and

          (n) use its best efforts to cause such Registrable Securities covered
by such registration statement to be registered with or approved by such other
governmental agencies or authorities as may be necessary to enable the sellers
thereof to consummate the disposition of the Registrable Securities (including
using its best efforts to take all such actions as may be necessary to enable
the sellers of such Registrable Securities to trade such Registrable Securities
on all non-U.S. securities exchanges or markets on which Registrable Securities
may then be listed or traded, in accordance with all applicable securities laws
or regulations).

          5.  Registration Expenses.
              ---------------------

          (a) Expenses.  All expenses incident to the Company's performance of
or compliance with this Agreement, including without limitation all registration
and filing fees, fees and expenses of compliance with securities or blue sky
laws, printing expenses, messenger and delivery expenses, fees and disbursements
of custodians, and fees and disbursements of counsel for the Company and all
independent certified public accountants, underwriters (excluding discounts and
commissions) and other Persons retained by the Company (all such expenses being
herein called

                                      -8-
<PAGE>

"Registration Expenses"), shall be borne as provided in this Agreement, except
that the Company shall, in any event, pay its internal expenses (including,
without limitation, all salaries and expenses of its officers and employees
performing legal or accounting duties), the expense of any annual audit or
quarterly review, the expense of any liability insurance and the expenses and
fees for listing the securities to be registered on each securities exchange on
which similar securities issued by the Company are then listed or on the Nasdaq.

          (b) Reimbursement of Counsel.  In connection with each Demand
Registration and each Piggyback Registration, the Company shall reimburse the
holders of Registrable Securities included in such registration (i) for the
reasonable fees and disbursements (not to exceed $20,000 for any one
registration) of one counsel chosen by the holders of a majority of the
Purchaser Registrable Securities (or, if none, Registrable Securities) included
in such registration and (ii) for the reasonable fees and disbursements (not to
exceed $5,000 per additional counsel for any one registration) of each
additional counsel retained by any holder of Registrable Securities solely for
the purpose of rendering a legal opinion to underwriters on behalf of such
holder in connection with any underwritten Demand Registration or Piggyback
Registration.

          (c) Payment of Certain Expenses by Holders of Registrable Securities.
Underwriting discounts and commissions and transfer taxes relating to the
Registrable Securities included in any registration hereunder, and all fees and
expenses of counsel for any holder of Registrable Securities (other than fees
and expenses to be reimbursed by the Company as set forth in paragraph (b)
above) shall be borne and paid by the holders of such Registrable Securities.

          6.  Indemnification.
              ---------------

          (a) The Company agrees to indemnify, to the extent permitted by law,
each holder of Registrable Securities, its officers and directors and each
Person that controls such holder (within the meaning of the Securities Act)
against all losses, claims, damages, liabilities and expenses caused by any
untrue or alleged untrue statement of material fact contained in any
registration statement, prospectus or preliminary prospectus or any amendment
thereof or supplement thereto or any omission or alleged omission of a material
fact required to be stated therein or necessary to make the statements therein
not misleading, except insofar as the same are caused by or contained in any
information furnished in writing to the Company by such holder expressly for use
therein or by such holder's failure to deliver a copy of the registration
statement or prospectus or any amendments or supplements thereto after the
Company has furnished such holder with a sufficient number of copies of the
same.  In connection with an underwritten offering, the Company shall indemnify
such underwriters, their officers and directors and each Person who controls
such underwriters (within the meaning of the Securities Act) to the same extent
as provided above with respect to the indemnification of the holders of
Registrable Securities.

          (b) In connection with any registration statement in which a holder of
Registrable Securities is participating, each such holder shall furnish to the
Company in writing such information and affidavits as the Company reasonably
requests for use in connection with any such registration

                                      -9-
<PAGE>

statement or prospectus and, to the extent permitted by law, shall indemnify the
Company, its directors and officers and each Person who controls the Company
(within the meaning of the Securities Act) against any losses, claims, damages,
liabilities and expenses resulting from any untrue or alleged untrue statement
of material fact contained in the registration statement, prospectus or
preliminary prospectus or any amendment thereof or supplement thereto or any
omission or alleged omission of a material fact required to be stated therein or
necessary to make the statements therein not misleading, but only to the extent
that such untrue statement or omission is contained in any information or
affidavit so furnished in writing by such holder; provided that the obligation
to indemnify shall be individual, not joint and several, for each holder and
shall be limited to the net amount of proceeds received by such holder from the
sale of Registrable Securities pursuant to such registration statement.

          (c) Any Person entitled to indemnification hereunder shall (i) give
prompt written notice to the indemnifying party of any claim with respect to
which it seeks indemnification (provided that the failure to give prompt notice
shall not impair any Person's right to indemnification hereunder to the extent
such failure has not prejudiced the indemnifying party) and (ii) unless in such
indemnified party's reasonable judgment a conflict of interest between such
indemnified and indemnifying parties may exist with respect to such claim,
permit such indemnifying party to assume the defense of such claim with counsel
reasonably satisfactory to the indemnified party.  If such defense is assumed,
the indemnifying party shall not be subject to any liability for any settlement
made by the indemnified party without its consent (but such consent shall not be
unreasonably withheld).  An indemnifying party who is not entitled to, or elects
not to, assume the defense of a claim shall not be obligated to pay the fees and
expenses of more than one counsel for all parties indemnified by such
indemnifying party with respect to such claim, unless in the reasonable judgment
of any indemnified party a conflict of interest may exist between such
indemnified party and any other of such indemnified parties with respect to such
claim.

          (d) The indemnification provided for under this Agreement shall remain
in full force and effect regardless of any investigation made by or on behalf of
the indemnified party or any officer, director or controlling Person of such
indemnified party and shall survive the transfer of securities.  The Company
also agrees to make such provisions, as are reasonably requested by any
indemnified party, for contribution to such party in the event the Company's
indemnification is unavailable for any reason such that such provisions provide
the same obligations and benefits to the indemnified party as those which would
have been applicable had the indemnification provisions in paragraphs 6(a) and
(b) been available taking into account all of the limitations set forth in
paragraphs 6(a) and (b).

          7.  Participation in Underwritten Registrations.  No Person may
participate in any registration hereunder which is underwritten unless such
Person (i) agrees to sell such Person's securities on the basis provided in any
underwriting arrangements approved by the Person or Persons entitled hereunder
to approve such arrangements and (ii) completes and executes all questionnaires,
powers of attorney, indemnities, underwriting agreements and other documents
required under the terms of such underwriting arrangements; provided that no
holder of Registrable Securities included

                                      -10-
<PAGE>

in any underwritten registration shall be required to make any representations
or warranties to the Company or the underwriters (other than representations and
warranties regarding such holder and such holder's intended method of
distribution) or to undertake any indemnification obligations to the Company
with respect thereto, except as otherwise provided in paragraph 6(b) hereof, or
to the underwriters with respect thereto, except to the extent of the
indemnification being given to the Company and its controlling persons in
paragraph 6(a) hereof.

          8.   Definitions.
               -----------

          "Agreement" has the meaning set forth with respect thereto in the
preamble (it being understood that the term "Agreement" refers to this First
Supplement only for purposes of this First Supplement, and the term "Agreement"
as used in the Second Amended Agreement will continue to refer to the Second
Amended Agreement for purposes of all provisions of the Second Amended Agreement
(other than the supplementary provisions set forth in this First Supplement).

          "Allen" has the meaning set forth with respect thereto in the
preamble.

          "Board" means the board of management of the Company or, if the
Company is hereafter converted into another entity form, the board of directors
or comparable governing body of the Company.

          "Clevenger" has the meaning set forth with respect thereto in the
preamble.

          "Clevenger LLC" has the meaning set forth with respect thereto in the
preamble.

          "Common Stock" means the Ordinary Shares and, in the event the Company
has hereafter converted into another entity form, the common stock or other
comparable common equity securities of the Company.

          "Common Units" means the Common Units of CompleTel LLC, having the
rights and preferences set forth with respect thereto in the LLC Agreement.

          "Company" has the meaning set forth with respect thereto in the
preamble (it being understood that the term "Company" refers to CompleTel Europe
N.V. only for purposes of this Agreement, and the term "Company" as used in the
Second Amended Agreement will continue to refer to CompleTel LLC for purposes of
all provisions of the Second Amended Agreement (other than the supplementary
provisions set forth in this Agreement).

          "CompleTel LLC" has the meaning set forth with respect thereto in the

          "DeGeorge" has the meaning set forth with respect thereto in the
preamble.

          "DeGeorge Holdings" has the meaning set forth with respect thereto in
the preamble.

                                      -11-
<PAGE>

          "DeGeorge Registrable Securities" means Registrable Securities derived
from or relating to the Preferred Units issued to DeGeorge under the Equity
Purchase Agreement.

          "Demand Notice" has the meaning set forth with respect thereto in
Section 1(a).

          "Demand Registration" has the meaning set forth with respect thereto
in Section 1(a).

          "Dovey" has the meaning set forth with respect thereto in the
preamble.

          "Dovey LLC" has the meaning set forth with respect thereto in the
preamble.

          "Equity Purchase Agreement" means that certain Second Amended and
Restated Equity Purchase Agreement dated as of the date hereof, by and among
CompleTel LLC, the Investors, and the other Persons listed on the signature
pages thereto, as amended from time to time in accordance with its terms.

          "Executive Securities Agreements" has the meaning set forth with
respect thereto in the Equity Purchase Agreement.

          "First Amended Agreement" has the meaning set forth with respect
thereto in the preamble.

          "Holland" has the meaning set forth with respect thereto in the
preamble.

          "Hundt" has the meaning set forth with respect thereto in the
preamble.

          "Investor" and "Investors" have the meaning set forth with respect
thereto in the preamble.

          "Karafiol" has the meaning set forth with respect thereto in the
preamble.

          "Kirsch" has the meaning set forth with respect thereto in the
preamble.

          "Lacey" has the meaning set forth with respect thereto in the
preamble.

          "Laub" has the meaning set forth with respect thereto in the preamble.

          "LLC Agreement" means that certain limited liability company agreement
governing the affairs of CompleTel LLC, by and among the Investors and the other
holders of unit membership interests in CompleTel LLC, as amended from time to
time in accordance with its terms.

          "Long-Form Registration" has the meaning set forth with respect
thereto in Section 1(a).

                                     -12-
<PAGE>

          "MDCP" has the meaning set forth with respect thereto in the preamble.

          "MDCP Registrable Securities" means Registrable Securities derived
from or relating to the Preferred Units issued to MDCP under the Equity Purchase
Agreement.

          "Meritage" has the meaning set forth with respect thereto in the
preamble.

          "Meritage Registrable Securities" means Registrable Securities derived
from or relating to the Preferred Units issued to Meritage under the Equity
Purchase Agreement.

          "NASD" has the meaning set forth with respect thereto in Section 4(f).

          "Northwestern" has the meaning set forth with respect thereto in the
preamble.

          "Ordinary Shares" means the ordinary shares of the Company, euro .10
nominal value per share, having the rights and preferences set forth with
respect thereto in the articles of association of the Compnay.

          "Pearson" has the meaning set forth with respect thereto in the
preamble.

          "Pearson LLC #2" has the meaning set forth with respect thereto in the
preamble.

          "Performance Vesting Agreement" means that certain Second Amended and
Restated Performance Vesting Agreement dated as of the date hereof, by and among
CompleTel LLC, the Investors, and the other Persons listed on the signature
pages thereto, as amended from time to time in accordance with its terms.

          "Person" means an individual, a partnership, a corporation, a limited
liability company, an association, a joint stock company, a trust, a joint
venture, an unincorporated organization and a governmental entity or any
department, agency or political subdivision thereof.

          "Piggyback Registration" has the meaning set forth with respect
thereto in Section 2(a).

          "Preferred Units" means the Preferred Units of CompleTel LLC, having
the rights and preferences set forth with respect thereto in the LLC Agreement.

          "Prior Agreement" has the meaning set forth with respect thereto in
the preamble.

          "Purchaser Registrable Securities" means Registrable Securities
derived from or relating to the Preferred Units issued to the Investors and the
other purchasers under the Equity Purchase Agreement.

                                      -13-
<PAGE>

          "Registrable Securities" means (i) Common Stock which as of the date
hereof is beneficially represented by any Preferred Units issued under the
Equity Purchase Agreement (or by any Common Units issued upon conversion of any
such Preferred Units), (ii) Common Stock which as of the date hereof is
beneficially represented by any Common Units issued under the Executive
Securities Agreements (other than any Un-Performance-Vested Securities), (iii)
any Common Stock issued or issuable with respect to the securities referred to
in clauses (i) and (ii) by way of a stock dividend or stock split or in
connection with a combination of shares, recapitalization, merger, consolidation
or other reorganization, or upon conversion or exercise of any such securities,
and (iv) any other Common Stock of the Company held by any holder of Registrable
Securities; provided that with respect to any Registrable Securities, such
securities shall cease to be Registrable Securities when they have been (A)
effectively registered under the Securities Act and disposed of in accordance
with the registration statement covering them, (B) distributed to the public
through a broker, dealer or market maker pursuant to Rule 144 under the
Securities Act (or any similar rule promulgated by the Securities and Exchange
Commission then in force), (C) distributed to a partner of MDCP or Meritage and
become eligible to be sold by such partner pursuant to Rule 144(k) of the
Securities Act (or any similar rule promulgated by the Securities and Exchange
Commission then in force), or (D) repurchased or otherwise acquired by the
Company (or its assignees).  For purposes of this Agreement, a Person shall be
deemed to be the holder of Registrable Securities, and the Registrable
Securities shall be deemed to be outstanding and in existence, whenever such
Person has the right to acquire such Registrable Securities upon conversion of
preferred stock or similar securities held by such Person, or upon distribution
of such Registrable Securities in respect of securities held by such Person
which beneficially represent such Registrable Securities, whether or not such
acquisition has actually been effected, and such Person shall be entitled to
exercise the rights of a holder of such Registrable Securities hereunder.

          "Registration Expenses" has the meaning set forth with respect thereto
in Section 5(a).

          "SCI" has the meaning set forth with respect thereto in the preamble.

          "Securities Act" means the Securities Act of 1933, as amended from
time to time.

          "Securityholders Agreement" means that certain Second Amended and
Restated Securityholders Agreement dated as of the date hereof, by and between
CompleTel LLC and certain of its securityholders, as amended from time to time
in accordance with its terms.

          "Short-Form Registrations" has the meaning set forth with respect
thereto in Section 1(a).

          "Un-Performance-Vested Securities" means any CompleTel LLC securities
which are subject to performance vesting, but have not yet performance vested,
pursuant to the provisions of the Performance Vesting Agreement.

                                      -14-
<PAGE>

          9.   Miscellaneous.
               -------------

          (a) No Inconsistent Agreements.  The Company shall not hereafter enter
into any agreement with respect to its securities which is inconsistent with or
violates the rights granted to the holders of Registrable Securities in this
Agreement.

          (b) Adjustments Affecting Registrable Securities.  The Company shall
not take any action, or permit any change to occur, with respect to its
securities which would materially and adversely affect the ability of the
holders of Registrable Securities to include such Registrable Securities in a
registration undertaken pursuant to this Agreement or which would materially and
adversely affect the marketability of such Registrable Securities in any such
registration (including, without limitation, effecting a stock split or a
combination of shares).

          (c) Remedies.  Any Person having rights under any provision of this
Agreement shall be entitled to enforce such rights specifically, to recover
damages caused by reason of any breach of any provision of this Agreement and to
exercise all other rights granted by law.  The parties hereto agree and
acknowledge that money damages may not be an adequate remedy for any breach of
the provisions of this Agreement and that any party may in its sole discretion
apply to any court of law or equity of competent jurisdiction (without posting
any bond or other security) for specific performance and for other injunctive
relief in order to enforce or prevent violation of the provisions of this
Agreement.

          (d) Effectiveness of this Agreement.  This Agreement amending and
supplementing the Second Amended Agreement will be valid, binding, and effective
against the Company when it has been signed by the Company.  This Agreement
amending and supplementing the Second Amended Agreement will be valid, binding,
and effective against each party to the Second Amended Agreement when such party
has executed the Omnibus Amendment.  Pursuant to the provisions of Section 9(d)
of the Second Amended Agreement, this Agreement amending and supplementing the
Second Amended Agreement will be valid, binding, and effective against all
parties to the Second Amended Agreement when the Omnibus Amendment has been
signed by CompleTel LLC and the holders of a majority of the outstanding
Purchaser Registrable Securities. The effectiveness of this Agreement is subject
to the conditions thereto set forth in the Omnibus Amendment.

          (e) Successors and Assigns.  All covenants and agreements in this
Agreement by or on behalf of any of the parties hereto shall bind and inure to
the benefit of the respective successors and assigns of the parties hereto
whether so expressed or not.  In addition, whether or not any express assignment
has been made, the provisions of this Agreement which are for the benefit of
purchasers or holders of Registrable Securities are also for the benefit of, and
enforceable by, any subsequent holder of Registrable Securities.

          (f) Severability.  Whenever possible, each provision of this Agreement
shall be interpreted in such manner as to be effective and valid under
applicable law, but if any provision of

                                      -15-
<PAGE>

this Agreement is held to be prohibited
by or invalid under applicable law, such provision shall be ineffective only to
the extent of such prohibition or invalidity, without invalidating the remainder
of this Agreement.

          (g) Counterparts.  This Agreement may be executed simultaneously in
two or more counterparts, any one of which need not contain the signatures of
more than one party, but all such counterparts taken together shall constitute
one and the same Agreement.  Any management or other key employee of the Company
or its subsidiaries who purchases securities pursuant to an Executive Securities
Agreement may at any time after the date hereof, with the written approval of
the Company, become a party to this Agreement by executing a counterpart to this
Agreement agreeing to be bound by the provisions hereof as if such Person were
an original signatory hereto (which joinder shall not constitute an amendment,
modification, or waiver hereof).

          (h) Descriptive Headings; Interpretation; No Strict Construction.  The
descriptive headings of this Agreement are inserted for convenience only and do
not constitute a substantive part of this Agreement.  Whenever required by the
context, any pronoun used in this Agreement shall include the corresponding
masculine, feminine or neuter forms, and the singular forms of nouns, pronouns,
and verbs shall include the plural and vice versa.  Reference to any agreement,
document, or instrument means such agreement, document, or instrument as amended
or otherwise modified from time to time in accordance with the terms thereof,
and if applicable hereof.  The use of the words "include" or "including" in this
Agreement shall be by way of example rather than by limitation.  The use of the
words "or," "either" or "any" shall not be exclusive.  The parties hereto have
participated jointly in the negotiation and drafting of this Agreement.  If an
ambiguity or question of intent or interpretation arises, this Agreement shall
be construed as if drafted jointly by the parties hereto, and no presumption or
burden of proof shall arise favoring or disfavoring any party by virtue of the
authorship of any of the provisions of this Agreement.

          (i) Governing Law.  All issues and questions concerning the
construction, validity, interpretation and enforcement of this Agreement and the
exhibits and schedules hereto shall be governed by, and construed in accordance
with, the laws of the State of Delaware, without giving effect to any choice of
law or conflict of law rules or provisions (whether of the State of Delaware or
any other jurisdiction) that would cause the application of the laws of any
jurisdiction other than the State of Delaware.

          (j) Notices.  All notices, demands or other communications to be given
or delivered under or by reason of the provisions of this Agreement shall be in
writing and shall be deemed to have been given when (a) delivered personally to
the recipient, (b) telecopied to the recipient (with hard copy sent to the
recipient by reputable overnight courier service (charges prepaid) that same
day) if telecopied before 5:00 p.m. Chicago, Illinois time on a business day,
and otherwise on the next business day, or (c) one business day after being sent
to the recipient by reputable overnight courier service (charges prepaid).  Such
notices, demands and other communications shall be sent to CompleTel LLC at the
address set forth below, to the Company at the address therefor listed in
CompleTel LLC's records, and to any holder of Registrable Securities

                                      -16-
<PAGE>

at such address as indicated by the Company's records, or at such address or to
the attention of such other person as the recipient party has specified by prior
written notice to the sending party. CompleTel LLC's address is:

          6300 Syracuse Way, Suite 355
          Englewood, Colorado 80111
          Attention:     Chief Executive Officer
          Telephone:     (303) 741-4788
          Telecopy:      (303) 741-4823

          (k) Business Days.  If any time period for giving notice or taking
action hereunder expires on a day which is a Saturday, Sunday or legal holiday
in the State of Colorado, the Republic of France, or the jurisdiction in which
the Company's principal office is located, the time period shall automatically
be extended to the business day immediately following such Saturday, Sunday or
legal holiday.

          (l) Delivery by Facsimile.  This Agreement, the agreements referred to
herein, and each other agreement or instrument entered into in connection
herewith or therewith or contemplated hereby or thereby, and any amendments
hereto or thereto, to the extent signed and delivered by means of a facsimile
machine, shall be treated in all manner and respects as an original agreement or
instrument and shall be considered to have the same binding legal effect as if
it were the original signed version thereof delivered in person.  At the request
of any party hereto or to any such agreement or instrument, each other party
hereto or thereto shall reexecute original forms thereof and deliver them to all
other parties.  No party hereto or to any such agreement or instrument shall
raise the use of a facsimile machine to deliver a signature or the fact that any
signature or agreement or instrument was transmitted or communicated through the
use of a facsimile machine as a defense to the formation or enforceability of a
contract and each such party forever waives any such defense.

                    *         *         *         *        *

                                      -17-
<PAGE>

    IN WITNESS WHEREOF, the undersigned has executed this First Supplement to
Second Amended and Restated Registration Agreement as of the date first written
above.


                         COMPLETEL EUROPE N.V.


                         By
                            -------------------------------------------
                                  James E. Dovey, its Managing Director

                                      -18-