AMENDMENT NO. 1
                                     TO THE
                            ICG COMMUNICATIONS, INC.
                             1998 STOCK OPTION PLAN




     Effective as of December 15, 1998, the ICG Communications,  Inc. 1998 Stock
Option Plan (the  "Plan") is hereby  amended as follows (all  capitalized  terms
used herein shall have the meanings given to them in the Plan):
     Section  V(B)(i) of the Plan is hereby amended by replacing such subsection
in its entirety by the following Section V(B)(i):

     B.   For Director Participants.

          I. General  Provisions  - Formula  Grant  Options.  (a) Subject to the
     terms and  conditions  of this  Section  V(B),  as of  January 1, 1998 each
     individual  who is  serving as a  Director  Participant  on such date shall
     automatically  be granted  Options to  purchase  twenty  thousand  (20,000)
     shares  of  Common  Stock,   subject  to   availability   under  the  Plan.
     Notwithstanding the foregoing, each individual who is serving as a Director
     Participant and receives formula grant options under Section V(B)(i) of the
     Corporation's 1996 Stock Option Plan, as amended,  shall not be eligible to

     receive  grants of Options under Section  V(B)(i) of this Plan covering the
     same  periods.   In  the  event  that  an  individual  becomes  a  Director
     Participant  during any Plan Quarter during the 1998 calendar year, but did
     not serve as a Director  Participant  on January 1, 1998,  such  individual
     shall  automatically  be  granted,  as of the  date  of  election  of  such
     individual  as a Director  Participant,  Options to purchase  that pro rata
     number  of shares of Common  Stock  for such  calendar  year as a  Director
     Participant  would  otherwise  be  entitled to receive  under this  Section
     V(B)(i) (at the rate of 5,000 shares per Plan Quarter,  subject to the last
     sentence of subparagraph (c) below).

     (b)  Subject  to the terms  and  conditions  of this  Section  V(B),  as of
December  15,  1998,  and as of December  15 of each  succeeding  calendar  year
through and including  December 15, 2006,  each  individual  who is serving as a
Director  Participant  on such date shall  automatically  be granted  Options to
purchase   twenty  thousand   (20,000)  shares  of  Common  Stock,   subject  to
availability under the Plan. Except as set forth in the following  sentence,  in
the event  that an  individual  becomes a Director  Participant  during any Plan
Quarter  subsequent to January 1, 1999, such individual  shall  automatically be
granted,  as  of  the  date  of  election  of  such  individual  as  a  Director
Participant,  Options to purchase that pro rata number of shares of Common Stock
for such calendar year as a Director  Participant would otherwise be entitled to
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receive  under  this  Section  V(B)(i)  (at the rate of 5,000 per Plan  Quarter,
subject to the following  sentence and to the last sentence of subparagraph  (c)
below). In the event that an individual  becomes a Director  Participant  during
the period from December 16 through  December 31 of any calendar year subsequent
to January 1, 1999,  the Director  Participant  shall  automatically  be granted
Options to purchase the same number of shares as the other Director Participants
were granted on the immediately  preceding December 15, which Options shall vest
over the course of the following  calendar year as set forth in subparagraph (c)
herein.

     (c) Subject to the provisions of Section VI hereunder,  the option price of
the shares of Common Stock covered by each Option shall be the Fair Market Value
of such shares on the date of the grant.  Each Option granted under this Section
V(B)(i)  by its terms  shall  expire  ten (10) years from the date of its grant.
Furthermore,  an Option  granted  pursuant to this Section  V(B)(i) shall become
exercisable  as to 5,000 shares of Common Stock covered  thereby on the last day
of the Plan Quarter  during which the date of grant occurs  (except with respect
to Options  granted on December 15 pursuant  to  subparagraph  (b) above,  which
shall  vest on March 31 of the  following  year)  and,  thereafter,  as to 5,000
shares on the last day of each of the next  succeeding Plan Quarters during such
year, respectively,  but only if, with regard to the shares of Common Stock with
respect to which the Option becomes  exercisable at the end of any Plan Quarter,
the Director  Participant has served in such capacity on an uninterrupted  basis
for more than fifty percent  (50%) of the business  days  contained in such Plan
Quarter.