<PAGE>   1

     As filed with the Securities and Exchange Commission on June 14, 2000

                                                           Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                               -----------------
                                    FORM S-8
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933

                               -----------------
                               MEDIA METRIX, INC.
             (Exact name of registrant as specified in its charter)

                 DELAWARE                                      11-3374729
     (State or other jurisdiction of                        (I.R.S. Employer
      incorporation or organization)                     Identification Number)


                        250 PARK AVENUE SOUTH, 7TH FLOOR
                            NEW YORK, NEW YORK 10003
                                 (212) 515-8700

  (Address, including zip code, and telephone number, including area code, of
                   registrant's principal executive offices)

                 MEDIA METRIX, INC. 2000 EQUITY INCENTIVE PLAN
              MEDIA METRIX, INC. 2000 EMPLOYEE STOCK PURCHASE PLAN

                           (full title of the plans)

                               -----------------
                                  TOD JOHNSON
                               MEDIA METRIX, INC.
                        250 PARK AVENUE SOUTH, 7TH FLOOR
                            NEW YORK, NEW YORK 10003
                                 (212) 515-8700

      (Name, address, including zip code, and telephone number, including
                        area code, of agent for service)

                               -----------------
Copies of all communications, including all communications sent to the agent for
                          service, should be sent to:

                             STEVEN I. SUZZAN, ESQ.
                          FULBRIGHT & JAWORSKI L.L.P.
                                666 FIFTH AVENUE
                           NEW YORK, NEW YORK  10103
                                 (212) 318-3000
                               -----------------
                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
===========================================================================================
                                        PROPOSED MAXIMUM    PROPOSED MAXIMUM    AMOUNT OF
 TITLE OF SECURITIES    AMOUNT TO BE     OFFERING PRICE        AGGREGATE       REGISTRATION
  TO BE REGISTERED       REGISTERED(1)      PER SHARE         OFFERING PRICE       FEE
===========================================================================================
<S>                    <C>              <C>                <C>                 <C>
COMMON STOCK $.01         2,000,000
PAR VALUE PER SHARE(3)     SHARES        $32.34375(2)       $64,687,500(2)      $17,077.50

COMMON STOCK $.01          100,000
PAR VALUE PER SHARE(4)     SHARES        $32.34375(2)       $3,234,375(2)         $853.88
===========================================================================================
</TABLE>

(1)  THIS REGISTRATION STATEMENT ALSO COVERS SUCH INDETERMINATE NUMBER OF
     ADDITIONAL SHARES OF COMMON STOCK AS IS NECESSARY TO ELIMINATE ANY DILUTIVE
     EFFECT OF ANY FUTURE STOCK DIVIDEND, STOCK SPLIT, RECAPITALIZATION OR
     SIMILAR TRANSACTION.
(2)  THE PRICE IS ESTIMATED IN ACCORDANCE WITH RULE 457(h) UNDER THE SECURITIES
     ACT OF 1933, AS AMENDED, SOLELY FOR THE PURPOSE OF CALCULATING THE
     REGISTRATION FEE, BASED ON THE AVERAGE OF THE HIGH AND LOW PRICES OF
     COMMON STOCK AS REPORTED ON THE NASDAQ NATIONAL MARKET ON JUNE 9, 2000.
(3)  COMMON STOCK ISSUABLE PURSUANT TO THE MEDIA METRIX, INC. 2000 EQUITY
     INCENTIVE PLAN.
(4)  COMMON STOCK ISSUABLE PURSUANT TO THE MEDIA METRIX, INC. 2000 EMPLOYEE
     STOCK PURCHASE PLAN.
<PAGE>   2



                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE

         The following documents filed by Media Metrix, Inc. (the "Company")
are incorporated herein by reference:

         (a)  The Company's Prospectus dated April 26, 2000 forming part of the
Registration Statement on Form S-1 filed on April 26, 2000;

         (b)  The Company's Quarterly Report on Form 10-Q for the quarter ended
March 31, 2000;

         (c)  The Company's Annual Report on Form 10-K for the fiscal year ended
December 31, 1999;

         (d)  The Company's Current Report on Form 8-K dated March 20, 2000;
and

         (e)  The description of the Company's Common Stock contained in Item
1 of the Company's Registration Statement on Form 8-A dated May 3, 1999.

         In addition to the foregoing, all documents subsequently filed by the
Company pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Securities
Exchange Act of 1934, prior to the filing of a post-effective amendment
indicating that all of the securities offered hereunder have been sold or
deregistering all securities then remaining unsold, shall be deemed to be
incorporated by reference in this Registration Statement and to be part hereof
from the date of filing of such documents. Any statement contained in a
document incorporated by reference in this Registration Statement shall be
deemed to be modified or superseded for purposes of this Registration Statement
to the extent that a statement contained herein or in any subsequently filed
document that is also incorporated by reference herein modifies or supersedes
such statement. Any statement so modified or superseded shall not be deemed,
except as so modified or superseded, to constitute a part of this Registration
Statement.

ITEM 4.  DESCRIPTION OF SECURITIES

         Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL

         Not applicable.


                                      II-1

<PAGE>   3


ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Section 145 of the General Corporation Law of the State of Delaware
permits indemnification of directors, officers and employees of a corporation
under certain conditions and subject to certain limitations. The Certificate of
Incorporation and By-laws of the Company provide that the Company shall
indemnify its directors and officers to the fullest extent permitted by the
Delaware Law, including those circumstances in which indemnification would
otherwise be discretionary, subject to certain exceptions. The By-laws also
provide that the Company shall advance expenses to directors and officers
incurred in connection with an action or proceeding as to which they may be
entitled to indemnification, subject to certain exceptions. In addition, the
Company has entered into Indemnity Agreements with its directors and officers
providing for the maximum indemnification allowed by Section 145.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Not Applicable.

ITEM 8.       EXHIBITS

              4    (a)*      Amended and Restated Certificate of Incorporation
                             of Media Metrix, Inc.

                   (b)*      Amended and Restated By-laws of Media Metrix, Inc.

                   (c)       Media Metrix, Inc. 2000 Employee Stock Purchase
                             Plan

                   (d)       Media Metrix, Inc. 2000 Equity Incentive Plan

              5              Opinion of Fulbright & Jaworski L.L.P.

              23   (a)       Consent of Ernst & Young L.L.P.

                   (b)       Consent of Fulbright & Jaworski L.L.P. (included
                             in Exhibit 5)

              24             Power of Attorney (included in signature page)

----------------------

*        Incorporated by reference to the Company's Registration Statement on
         Form S-1 (File No. 333-72883).


                                      II-2

<PAGE>   4


ITEM 9.  UNDERTAKINGS

         (a)  The undersigned registrant hereby undertakes:

              (1)  To file, during any period in which offers or sales are
                   being made, a post-effective amendment to this registration
                   statement:

                   (i)       To include any prospectus required by section
                             10(a)(3) of the Securities Act of 1933;

                   (ii)      To reflect in the prospectus any facts or events
                             arising after the effective date of the
                             registration statement (or the most recent
                             post-effective amendment thereof) which,
                             individually or in the aggregate, represent a
                             fundamental change in the information set forth in
                             the registration statement;

                   (iii)     To include any material information with respect
                             to the plan of distribution not previously
                             disclosed in the registration statement or any
                             material change to such information in the
                             registration statement;

              provided, however, that clauses (a)(1)(i) and (a)(1)(ii) shall
              not apply if the information required to be included in a
              post-effective amendment by those clauses is contained in
              periodic reports filed by or furnished to the Securities and
              Exchange Commission by the Registrant pursuant to Section 13 or
              Section 15(d) of the Securities Exchange Act of 1934 that are
              incorporated herein by reference;

              (2)  That, for the purpose of determining any liability under the
                   Securities Act of 1933, each such post-effective amendment
                   shall be deemed to be a new registration statement relating
                   to the securities offered therein, and the offering of such
                   securities at that time shall be deemed to be the initial
                   bona fide offering thereof; and

              (3)  To remove from registration by means of a post-effective
                   amendment any of the securities being registered which
                   remain unsold at the termination of the offering.

         (b)  The undersigned registrant hereby undertakes that, for purposes
              of determining any liability under the Securities Act of 1933,
              each filing of the registrant's annual report pursuant to Section
              13(a) or Section 15(d) of the Securities Exchange Act of 1934
              (and, where applicable, each filing of an employee benefit plan's
              annual report pursuant to Section 15(d) of the

                                      II-3

<PAGE>   5



              Securities Exchange Act of 1934) that is incorporated by
              reference in the registration statement shall be deemed to be a
              new registration statement relating to the securities offered
              therein, and the offering of such securities at that time shall
              be deemed to be the initial bona fide offering thereof.

         (c)  Insofar as indemnification for liabilities arising under the
              Securities Act of 1933 may be permitted to directors, officers
              and controlling persons of the registrant pursuant to the
              foregoing provisions, or otherwise, the registrant has been
              advised that in the opinion of the Securities and Exchange
              Commission such indemnification is against public policy as
              expressed in the Securities Act of 1933 and is, therefore,
              unenforceable.  In the event a claim for indemnification against
              such liabilities (other than the payment by the registrant of
              expenses incurred or paid by a director, officer, or controlling
              person of the registrant in the successful defense of any action,
              suit or proceeding) is asserted by such director, officer, or
              controlling person of the registrant in connection with the
              securities being registered, the registrant will, unless in the
              opinion of its counsel the matter has been settled by controlling
              precedent, submit to a court of appropriate jurisdiction the
              question whether such indemnification by it is against public
              policy as expressed in the Securities Act of 1933 and will be
              governed by the final adjudication of such issue.

                                      II-4

<PAGE>   6


                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, as
amended, the Registrant certifies that it has reasonable grounds to believe
that it meets all of the requirements for filing on Form S-8 and has duly
caused this Registration Statement to be signed on its behalf by the
undersigned, thereunto duly authorized, in the City of New York, State of New
York, on June 14, 2000.

                                    MEDIA METRIX, INC.

                                    By: /s/ Tod Johnson
                                       ---------------------------------------
                                        Tod Johnson
                                        Chairman and Chief Executive Officer

                               POWER OF ATTORNEY

     KNOW ALL MEN BY THESE PRESENTS, that each individual whose signature
appears below constitutes and appoints each of Tod Johnson and Thomas A. Lynch
as his true and lawful attorney-in-fact and agent, each acting alone, with full
power of substitution and resubstitution, for him and in his name, place and
stead, in any and all capacities, to sign any and all amendments to this
Registration Statement, including post-effective amendments, and to file the
same, with all exhibits thereto, and all documents in connection therewith,
with the Securities and Exchange Commission, granting unto each said
attorney-in-fact and agent full power and authority to do and perform each and
every act and thing requisite and necessary to be done in and about the
premises, as fully to all intents and purposes as he might or could do in
person, and hereby ratifies and confirms all that any said attorney-in-fact and
agent, each acting alone, or his substitute or substitutes, may lawfully do or
cause to be done by virtue hereof.

                                      II-5


<PAGE>   7



     Pursuant to the requirements of the Securities Act of 1933, as amended,
this Registration Statement has been signed below by the following persons in
the capacities and on the dates indicated.

<TABLE>
<CAPTION>
Signature                      Title                               Date
---------                      -----                               ----
<S>                           <C>                             <C>

/s/ Tod Johnson                Chief Executive Officer and     June 14, 2000
------------------------       Chairman of the Board
Tod Johnson                    (Principal Executive Officer)

                               Chief Financial Officer and     June 14, 2000
/s/ Thomas A. Lynch            Treasurer (Principal
------------------------       Financial and Accounting
Thomas A. Lynch                Officer)


------------------------
Randy Pausch                   Director                        June 14, 2000

/s/ Michael Brooks
------------------------
Michael Brooks                 Director                        June 14, 2000


------------------------
William W. Helman              Director                        June 14, 2000

/s/ Stig Kry
------------------------
Stig Kry                       Director                        June 14, 2000

/s/ James Mortensen
------------------------
James Mortensen                Director                        June 14, 2000
</TABLE>

                                      II-6

<PAGE>   8


                                 Exhibit Index

<TABLE>
<CAPTION>
        No.       Description
        ---       -----------
<S>               <C>
         4(a)*     Amended and Restated Certificate of Incorporation of Media
                   Metrix, Inc.

          (b)*     Amended and Restated Bylaws of Media Metrix, Inc.

          (c)      Media Metrix, Inc. 2000 Employee Stock Purchase Plan

          (d)      Media Metrix, Inc. 2000 Equity Incentive Plan

         5         Opinion of Fulbright & Jaworski L.L.P.

        23(a)      Consent of Ernst & Young L.L.P.

          (b)      Consent of Fulbright & Jaworski L.L.P. (included in Exhibit
                   5)

        24         Power of Attorney (included in signature page)
</TABLE>

----------------------

*    Incorporated by reference to the Company's Registration Statement on Form
     S-1 (File No. 333-72883), as amended.


                                      II-7
[{"type": "S-8", "sequence": "1", "filename": "0001.txt", "description": "MEDIA METRIX", "secsgml_size_bytes": 17317}]
{"company-data": {"conformed-name": "MEDIA METRIX INC", "cik": "0001039446", "assigned-sic": "7389", "irs-number": "113374729", "state-of-incorporation": "DE"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-39292", "film-number": "655163"}, "business-address": {"street1": "250 PARK AVENUE SOUTH", "street2": "7TH FLOOR", "city": "NEW YORK", "state": "NY", "zip": "10003", "phone": "2124607980"}}
1

     As filed with the Securities and Exchange Commission on June 14, 2000

                                                           Registration No. 333-
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                               -----------------
                                    FORM S-8
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933

                               -----------------
                               MEDIA METRIX, INC.
             (Exact name of registrant as specified in its charter)

                 DELAWARE                                      11-3374729
     (State or other jurisdiction of                        (I.R.S. Employer
      incorporation or organization)                     Identification Number)

                        250 PARK AVENUE SOUTH, 7TH FLOOR
                            NEW YORK, NEW YORK 10003
                                 (212) 515-8700

  (Address, including zip code, and telephone number, including area code, of
                   registrant's principal executive offices)

                 MEDIA METRIX, INC. 2000 EQUITY INCENTIVE PLAN
              MEDIA METRIX, INC. 2000 EMPLOYEE STOCK PURCHASE PLAN

                           (full title of the plans)

                               -----------------
                                  TOD JOHNSON
                               MEDIA METRIX, INC.
                        250 PARK AVENUE SOUTH, 7TH FLOOR
                            NEW YORK, NEW YORK 10003
                                 (212) 515-8700

      (Name, address, including zip code, and telephone number, including
                        area code, of agent for service)

                               -----------------
Copies of all communications, including all communications sent to the agent for
                          service, should be sent to:

                             STEVEN I. SUZZAN, ESQ.
                          FULBRIGHT & JAWORSKI L.L.P.
                                666 FIFTH AVENUE
                           NEW YORK, NEW YORK  10103
                                 (212) 318-3000
                               -----------------
                        CALCULATION OF REGISTRATION FEE
===========================================================================================
                                        PROPOSED MAXIMUM    PROPOSED MAXIMUM    AMOUNT OF
 TITLE OF SECURITIES    AMOUNT TO BE     OFFERING PRICE        AGGREGATE       REGISTRATION
  TO BE REGISTERED       REGISTERED(1)      PER SHARE         OFFERING PRICE       FEE
===========================================================================================
COMMON STOCK $.01         2,000,000
PAR VALUE PER SHARE(3)     SHARES        $32.34375(2)       $64,687,500(2)      $17,077.50

COMMON STOCK $.01          100,000
PAR VALUE PER SHARE(4)     SHARES        $32.34375(2)       $3,234,375(2)         $853.88
===========================================================================================
(1)  THIS REGISTRATION STATEMENT ALSO COVERS SUCH INDETERMINATE NUMBER OF
     ADDITIONAL SHARES OF COMMON STOCK AS IS NECESSARY TO ELIMINATE ANY DILUTIVE
     EFFECT OF ANY FUTURE STOCK DIVIDEND, STOCK SPLIT, RECAPITALIZATION OR
     SIMILAR TRANSACTION.
(2)  THE PRICE IS ESTIMATED IN ACCORDANCE WITH RULE 457(h) UNDER THE SECURITIES
     ACT OF 1933, AS AMENDED, SOLELY FOR THE PURPOSE OF CALCULATING THE
     REGISTRATION FEE, BASED ON THE AVERAGE OF THE HIGH AND LOW PRICES OF
     COMMON STOCK AS REPORTED ON THE NASDAQ NATIONAL MARKET ON JUNE 9, 2000.
(3)  COMMON STOCK ISSUABLE PURSUANT TO THE MEDIA METRIX, INC. 2000 EQUITY
     INCENTIVE PLAN.
(4)  COMMON STOCK ISSUABLE PURSUANT TO THE MEDIA METRIX, INC. 2000 EMPLOYEE
     STOCK PURCHASE PLAN.
2

                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE

         The following documents filed by Media Metrix, Inc. (the "Company")
are incorporated herein by reference:

         (a)  The Company's Prospectus dated April 26, 2000 forming part of the
Registration Statement on Form S-1 filed on April 26, 2000;

         (b)  The Company's Quarterly Report on Form 10-Q for the quarter ended
March 31, 2000;

         (c)  The Company's Annual Report on Form 10-K for the fiscal year ended
December 31, 1999;

         (d)  The Company's Current Report on Form 8-K dated March 20, 2000;
and

         (e)  The description of the Company's Common Stock contained in Item
1 of the Company's Registration Statement on Form 8-A dated May 3, 1999.

         In addition to the foregoing, all documents subsequently filed by the
Company pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Securities
Exchange Act of 1934, prior to the filing of a post-effective amendment
indicating that all of the securities offered hereunder have been sold or
deregistering all securities then remaining unsold, shall be deemed to be
incorporated by reference in this Registration Statement and to be part hereof
from the date of filing of such documents. Any statement contained in a
document incorporated by reference in this Registration Statement shall be
deemed to be modified or superseded for purposes of this Registration Statement
to the extent that a statement contained herein or in any subsequently filed
document that is also incorporated by reference herein modifies or supersedes
such statement. Any statement so modified or superseded shall not be deemed,
except as so modified or superseded, to constitute a part of this Registration
Statement.

ITEM 4.  DESCRIPTION OF SECURITIES

         Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL

         Not applicable.

                                      II-1
3

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Section 145 of the General Corporation Law of the State of Delaware
permits indemnification of directors, officers and employees of a corporation
under certain conditions and subject to certain limitations. The Certificate of
Incorporation and By-laws of the Company provide that the Company shall
indemnify its directors and officers to the fullest extent permitted by the
Delaware Law, including those circumstances in which indemnification would
otherwise be discretionary, subject to certain exceptions. The By-laws also
provide that the Company shall advance expenses to directors and officers
incurred in connection with an action or proceeding as to which they may be
entitled to indemnification, subject to certain exceptions. In addition, the
Company has entered into Indemnity Agreements with its directors and officers
providing for the maximum indemnification allowed by Section 145.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Not Applicable.

ITEM 8.       EXHIBITS

              4    (a)*      Amended and Restated Certificate of Incorporation
                             of Media Metrix, Inc.

                   (b)*      Amended and Restated By-laws of Media Metrix, Inc.

                   (c)       Media Metrix, Inc. 2000 Employee Stock Purchase
                             Plan

                   (d)       Media Metrix, Inc. 2000 Equity Incentive Plan

              5              Opinion of Fulbright & Jaworski L.L.P.

              23   (a)       Consent of Ernst & Young L.L.P.

                   (b)       Consent of Fulbright & Jaworski L.L.P. (included
                             in Exhibit 5)

              24             Power of Attorney (included in signature page)

----------------------

*        Incorporated by reference to the Company's Registration Statement on
         Form S-1 (File No. 333-72883).

                                      II-2
4

ITEM 9.  UNDERTAKINGS

         (a)  The undersigned registrant hereby undertakes:

              (1)  To file, during any period in which offers or sales are
                   being made, a post-effective amendment to this registration
                   statement:

                   (i)       To include any prospectus required by section
                             10(a)(3) of the Securities Act of 1933;

                   (ii)      To reflect in the prospectus any facts or events
                             arising after the effective date of the
                             registration statement (or the most recent
                             post-effective amendment thereof) which,
                             individually or in the aggregate, represent a
                             fundamental change in the information set forth in
                             the registration statement;

                   (iii)     To include any material information with respect
                             to the plan of distribution not previously
                             disclosed in the registration statement or any
                             material change to such information in the
                             registration statement;

              provided, however, that clauses (a)(1)(i) and (a)(1)(ii) shall
              not apply if the information required to be included in a
              post-effective amendment by those clauses is contained in
              periodic reports filed by or furnished to the Securities and
              Exchange Commission by the Registrant pursuant to Section 13 or
              Section 15(d) of the Securities Exchange Act of 1934 that are
              incorporated herein by reference;

              (2)  That, for the purpose of determining any liability under the
                   Securities Act of 1933, each such post-effective amendment
                   shall be deemed to be a new registration statement relating
                   to the securities offered therein, and the offering of such
                   securities at that time shall be deemed to be the initial
                   bona fide offering thereof; and

              (3)  To remove from registration by means of a post-effective
                   amendment any of the securities being registered which
                   remain unsold at the termination of the offering.

         (b)  The undersigned registrant hereby undertakes that, for purposes
              of determining any liability under the Securities Act of 1933,
              each filing of the registrant's annual report pursuant to Section
              13(a) or Section 15(d) of the Securities Exchange Act of 1934
              (and, where applicable, each filing of an employee benefit plan's
              annual report pursuant to Section 15(d) of the

                                      II-3
5

              Securities Exchange Act of 1934) that is incorporated by
              reference in the registration statement shall be deemed to be a
              new registration statement relating to the securities offered
              therein, and the offering of such securities at that time shall
              be deemed to be the initial bona fide offering thereof.

         (c)  Insofar as indemnification for liabilities arising under the
              Securities Act of 1933 may be permitted to directors, officers
              and controlling persons of the registrant pursuant to the
              foregoing provisions, or otherwise, the registrant has been
              advised that in the opinion of the Securities and Exchange
              Commission such indemnification is against public policy as
              expressed in the Securities Act of 1933 and is, therefore,
              unenforceable.  In the event a claim for indemnification against
              such liabilities (other than the payment by the registrant of
              expenses incurred or paid by a director, officer, or controlling
              person of the registrant in the successful defense of any action,
              suit or proceeding) is asserted by such director, officer, or
              controlling person of the registrant in connection with the
              securities being registered, the registrant will, unless in the
              opinion of its counsel the matter has been settled by controlling
              precedent, submit to a court of appropriate jurisdiction the
              question whether such indemnification by it is against public
              policy as expressed in the Securities Act of 1933 and will be
              governed by the final adjudication of such issue.

                                      II-4
6

                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, as
amended, the Registrant certifies that it has reasonable grounds to believe
that it meets all of the requirements for filing on Form S-8 and has duly
caused this Registration Statement to be signed on its behalf by the
undersigned, thereunto duly authorized, in the City of New York, State of New
York, on June 14, 2000.

                                    MEDIA METRIX, INC.

                                    By: /s/ Tod Johnson
                                       ---------------------------------------
                                        Tod Johnson
                                        Chairman and Chief Executive Officer

                               POWER OF ATTORNEY

     KNOW ALL MEN BY THESE PRESENTS, that each individual whose signature
appears below constitutes and appoints each of Tod Johnson and Thomas A. Lynch
as his true and lawful attorney-in-fact and agent, each acting alone, with full
power of substitution and resubstitution, for him and in his name, place and
stead, in any and all capacities, to sign any and all amendments to this
Registration Statement, including post-effective amendments, and to file the
same, with all exhibits thereto, and all documents in connection therewith,
with the Securities and Exchange Commission, granting unto each said
attorney-in-fact and agent full power and authority to do and perform each and
every act and thing requisite and necessary to be done in and about the
premises, as fully to all intents and purposes as he might or could do in
person, and hereby ratifies and confirms all that any said attorney-in-fact and
agent, each acting alone, or his substitute or substitutes, may lawfully do or
cause to be done by virtue hereof.

                                      II-5
7

     Pursuant to the requirements of the Securities Act of 1933, as amended,
this Registration Statement has been signed below by the following persons in
the capacities and on the dates indicated.
Signature                      Title                               Date
---------                      -----                               ----
/s/ Tod Johnson                Chief Executive Officer and     June 14, 2000
------------------------       Chairman of the Board
Tod Johnson                    (Principal Executive Officer)

                               Chief Financial Officer and     June 14, 2000
/s/ Thomas A. Lynch            Treasurer (Principal
------------------------       Financial and Accounting
Thomas A. Lynch                Officer)

------------------------
Randy Pausch                   Director                        June 14, 2000

/s/ Michael Brooks
------------------------
Michael Brooks                 Director                        June 14, 2000

------------------------
William W. Helman              Director                        June 14, 2000

/s/ Stig Kry
------------------------
Stig Kry                       Director                        June 14, 2000

/s/ James Mortensen
------------------------
James Mortensen                Director                        June 14, 2000
II-6
8

                                 Exhibit Index
No.       Description
        ---       -----------
4(a)*     Amended and Restated Certificate of Incorporation of Media
                   Metrix, Inc.

          (b)*     Amended and Restated Bylaws of Media Metrix, Inc.

          (c)      Media Metrix, Inc. 2000 Employee Stock Purchase Plan

          (d)      Media Metrix, Inc. 2000 Equity Incentive Plan

         5         Opinion of Fulbright & Jaworski L.L.P.

        23(a)      Consent of Ernst & Young L.L.P.

          (b)      Consent of Fulbright & Jaworski L.L.P. (included in Exhibit
                   5)

        24         Power of Attorney (included in signature page)
----------------------

*    Incorporated by reference to the Company's Registration Statement on Form
     S-1 (File No. 333-72883), as amended.

                                      II-7