<PAGE>   1
       AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 7, 1997
                                                           REGISTRATION NO. 333-
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   ----------

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           The Securities Act of 1933

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

                           PAIRGAIN TECHNOLOGIES, INC.
             (Exact name of Registrant as specified in its charter)

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

<TABLE>
<S>                                                       <C>       
        DELAWARE                                                 33-0282809
(State or other jurisdiction                                  (I.R.S. Employer
of incorporation or organization)                         Identification Number)
</TABLE>

                              14402 FRANKLIN AVENUE
                            TUSTIN, CALIFORNIA 92780
               (Address of principal executive offices) (zip code)

                                   ----------

                              AVIDIA SYSTEMS, INC.
                                 1996 STOCK PLAN
                            (Full title of the plan)

                                   ----------

                               CHARLES S. STRAUCH
                      CHAIRMAN AND CHIEF EXECUTIVE OFFICER
                           PAIRGAIN TECHNOLOGIES, INC.
                              14402 FRANKLIN AVENUE
                            TUSTIN, CALIFORNIA 92780
                                 (714) 832-9922

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

                                   ----------

<TABLE>
<CAPTION>
===============================================================================================================
                                                         Proposed maximum   Proposed maximum
                                          Amount to be    offering price        aggregate         Amount of
Title of securities to be registered     registered(1)      per share(2)   offering price(2)   registration fee
---------------------------------------------------------------------------------------------------------------
<S>                                      <C>             <C>               <C>                 <C>
Options to Purchase Common Stock            232,564               N/A            N/A                 N/A

Common Stock, $.0005 par value              232,564             $1.78          $413,964              $126
===============================================================================================================
</TABLE>

(1) This Registration Statement shall also cover any additional shares of Common
Stock which become issuable under the Avidia Systems, Inc. 1996 Stock Plan by
reason of any stock dividend, stock split, recapitalization or other similar
transaction effected without the receipt of consideration which results in an
increase in the number of the Registrant's outstanding shares of Common Stock.

(2) Calculated solely for purposes of this offering under Rule 457(h) of the
Securities Act of 1933, as amended, on the basis of the weighted average
exercise price of the outstanding options.


<PAGE>   2
                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE

            PairGain Technologies, Inc., a Delaware corporation (the
"Registrant"), hereby incorporates by reference into this Registration Statement
the following documents which were previously filed with the Securities and
Exchange Commission (the "SEC"):

      (a)   The Registrant's Annual Report on Form 10-K/A for the year ended
            December 31, 1996 filed pursuant to Section 13(a) of the Securities
            Exchange Act of 1934, as amended (the "1934 Act"), on April 30,
            1997;

      (b)   The Registrant's Current Report on Form 8-K filed with the SEC on
            March 5, 1997;

      (c)   The Registrant's Current Report on Form 8-K/A filed with the SEC on
            April 25, 1997; and

      (d)   The Registrant's Registration Statement No. 0-22202 on Form 8-A
            filed with the SEC on August 6, 1993 pursuant to Section 12 of the
            1934 Act, in which there is described the terms, rights and
            provisions applicable to the Registrant's outstanding Common Stock.

            All reports and definitive proxy or information statements filed by
the Registrant pursuant to Section 13(a), 13(c), 14 or 15(d) of the 1934 Act
after the date of this Registration Statement and prior to the filing of a
post-effective amendment which indicates that all securities offered hereby have
been sold or which deregisters all securities then remaining unsold at the time
of such amendment will be deemed to be incorporated by reference into this
Registration Statement and to be a part hereof from the date of filing of such
documents. Any statement contained in a document incorporated or deemed to be
incorporated by reference herein 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 which also is deemed to
be incorporated by reference herein modifies or supersedes such statement. Any
such 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.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Under Section 145 of the Delaware General Corporation Law, the
Registrant has broad powers to indemnify its directors and officers against
liabilities they may incur in such capacities, including liabilities under the
Securities Act of 1933, as amended (the "1933 Act"). The Registrant's Bylaws
provide that the Registrant will indemnify its directors and officers to the
fullest extent permitted by law and require the Registrant to advance litigation
expenses upon receipt by the Registrant of an undertaking by the director or
officer to repay such advances if it is ultimately determined that the director
or officer is not entitled to indemnification. The Bylaws further provide that
rights conferred under such Bylaws shall not be deemed to be exclusive of any
other right such persons may have or acquire under any bylaw, agreement, vote of
stockholders or disinterested directors or otherwise.

         The Registrant's Restated Certificate of Incorporation provides that,
pursuant to Delaware Law, its directors shall not be liable for monetary damages
for breach of the directors' fiduciary duty of care to the Registrant and its
stockholders. This provision in the Restated Certificate of Incorporation does
not eliminate the duty of care, and, in appropriate circumstances, equitable
remedies such as injunctive or other forms of non-monetary relief will remain
available under Delaware Law. In addition, each director will continue to be
subject to liability for breach of the director's duty of loyalty to the
Registrant or its stockholders, for acts or omissions not in good faith or
involving intentional misconduct or knowing violations of law, for actions
leading to improper personal benefit to the director, and for payment of
dividends or approval of stock repurchases or redemptions that are unlawful
under Delaware Law. The provision also does not affect a director's
responsibilities under any other law, such as the federal securities law or
state or federal environmental laws.

         In addition, the Registrant has entered into agreements to indemnify
its directors and certain of its officers beyond the indemnification provided
for in the Restated Certificate of Incorporation and Bylaws. These agreements




                                      II-1
<PAGE>   3
will, among other things, indemnify the Registrant's directors and certain of
its officers for certain expenses (including attorneys' fees), judgments, fines
and settlement amounts incurred by such person in any action or proceeding,
including any action by or in the right of the Registrant, on account of
services as a director or officer of the Registrant, or as a director or officer
of any other company or enterprise to which the person provides services at the
request of the Registrant.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

            Not Applicable.

ITEM 8.  EXHIBITS

<TABLE>
<CAPTION>
Exhibit Number    Exhibit
--------------    -------
<S>          <C>
    4        Instruments Defining Rights of Stockholders. Reference is made to
             Registrant's Registration Statement No. 0-22202 on Form 8-A, which
             is incorporated herein by reference pursuant to Item 3(d) of this
             Registration Statement.
    5        Opinion and consent of Brobeck, Phleger & Harrison LLP.
    23.1     Independent Auditors' Consent - Deloitte & Touche LLP.
    23.2     Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit
             5.
    24       Power of Attorney. Reference is made to page II-4 of this
             Registration Statement.
    99.1     Avidia Systems, Inc. (formerly ATM Products, Inc.) 1996 Stock Plan.
    99.2     Form of Incentive Stock Option.
    99.3     Form of Non-Qualified Stock Option Agreement.
    99.4     Form of Stock Option Assumption Agreement.
</TABLE>


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 1933 Act, (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, and (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 (1)(i) and (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 the Registrant pursuant to
Section 13 or Section 15(d) of the 1934 Act that are incorporated by reference
into the Registration Statement; (2) that for the purpose of determining any
liability under the 1933 Act, 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 AVIDIA Systems, Inc. 1996 Stock Plan.

              B. The undersigned Registrant hereby undertakes that, for purposes
of determining any liability under the 1933 Act, each filing of the Registrant's
annual report pursuant to Section 13(a) or Section 15(d) of the 1934 Act that is
incorporated by reference into 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
1933 Act may be permitted to directors, officers or controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the SEC such indemnification is against
public policy as expressed in the 1933 Act and is, therefore, unenforceable. In
the event that 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 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 1933 Act
and will be governed by the final adjudication of such issue.



                                      II-2
<PAGE>   4
                                   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 Tustin, State of California, on May 5, 1997.

                                    PAIRGAIN TECHNOLOGIES, INC.



                                    By: /s/ Charles S. Strauch
                                        ------------------------------------
                                        Charles S. Strauch, Chairman,
                                        Chief Executive Officer and Director

                                POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

               That the undersigned officers and directors of PairGain
Technologies, Inc., a Delaware corporation, do hereby constitute and appoint
Charles S. Strauch and Charles W. McBrayer, and each of them, the lawful
attorneys-in-fact and agents, with full power and authority to do any and all
acts and things and to execute any and all instruments which said attorneys and
agents, and any one of them, determine may be necessary or advisable or required
to enable said corporation to comply with the Securities Act of 1933, as
amended, and any rules or regulations or requirements of the Securities and
Exchange Commission in connection with this Registration Statement. Without
limiting the generality of the foregoing power and authority, the powers granted
include the power and authority to sign the names of the undersigned officers
and directors in the capacities indicated below to this Registration Statement,
to any and all amendments and supplements to this Registration Statement and to
any and all instruments or documents filed as part of or in conjunction with
this Registration Statement or to amendments or supplements thereof, and each of
the undersigned hereby ratifies and confirms all that said attorneys and agents,
or any one of them, shall do or cause to be done by virtue hereof. This Power of
Attorney may be signed in several counterparts.

               IN WITNESS WHEREOF, each of the undersigned has executed this
Power of Attorney as of the date indicated.

               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/ Charles S. Strauch        Chairman, Chief Executive Officer               May 5, 1997
Charles S. Strauch            and Director (Principal Executive Officer)



/s/ Charles W. McBrayer       Vice President, Finance and Administration,     May 5, 1997
-------------------------     Secretary and Chief Financial Officer
Charles W. McBrayer           (Principal Financial Officer)



/s/ Robert R. Price           Corporate Controller                            May 5, 1997
-------------------------     (Principal Accounting Officer)
Robert R. Price
</TABLE>



                                      II-3
<PAGE>   5
<TABLE>
<CAPTION>
SIGNATURE                     TITLE                                      DATE
---------                     -----                                      ----
<S>                           <C>                                        <C>    
/s/ Howard S. Flagg           President and Director                     May 5, 1997
--------------------------
Howard S. Flagg



/s/ Benedict A. Itri          Executive Vice President,                  May 5, 1997
--------------------------    Chief Technical Officer and Director
Benedict A. Itri              



/s/ Robert A. Hoff            Director                                   May 5, 1997
---------------------------
Robert A. Hoff



/s/ Robert C. Hawk            Director                                   May 5, 1997
----------------------------
Robert C. Hawk



/s/ B. Allen Lay              Director                                   May 5, 1997
----------------------------
B. Allen Lay
</TABLE>



                                      II-4
<PAGE>   6
                       SECURITIES AND EXCHANGE COMMISSION

                                WASHINGTON, D.C.



                                    EXHIBITS

                                       TO

                                    FORM S-8

                          UNDER SECURITIES ACT OF 1933


                           PAIRGAIN TECHNOLOGIES, INC.



<PAGE>   7
                                  EXHIBIT INDEX


<TABLE>
<CAPTION>
Exhibit
Number       Exhibit
------       -------
<S>          <C>
    4        Instruments Defining Rights of Stockholders. Reference is made to
             Registrant's Registration Statement No. 0-22202 on Form 8-A, which
             is incorporated herein by reference pursuant to Item 3(d) of this
             Registration Statement.

    5        Opinion and consent of Brobeck, Phleger & Harrison LLP.

    23.1     Independent Auditors' Consent - Deloitte & Touche LLP.

    23.2     Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit
             5.

    24       Power of Attorney. Reference is made to page II-4 of this
             Registration Statement.

    99.1     AVIDIA Systems, Inc. (formerly ATM Products, Inc.) 1996 Stock Plan.

    99.2     Form of Incentive Stock Option.

    99.3     Form of Non-Qualified Stock Option Agreement.

    99.4     Form of Stock Option Assumption Agreement.
</TABLE>
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 19147}]
{"company-data": {"conformed-name": "PAIRGAIN TECHNOLOGIES INC /CA/", "cik": "0000910032", "assigned-sic": "3661", "irs-number": "330282809", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-26643", "film-number": "97597490"}, "business-address": {"street1": "14402 FRANKLIN AVE", "city": "TUSTIN", "state": "CA", "zip": "92680", "phone": "7148329922"}, "mail-address": {"street1": "14402 FRANKLIN AVE", "city": "TUSTIN", "state": "CA", "zip": "92680-7013"}}
1
       AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 7, 1997
                                                           REGISTRATION NO. 333-
================================================================================
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   ----------

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           The Securities Act of 1933

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

                           PAIRGAIN TECHNOLOGIES, INC.
             (Exact name of Registrant as specified in its charter)

                                 -------------
DELAWARE                                                 33-0282809
(State or other jurisdiction                                  (I.R.S. Employer
of incorporation or organization)                         Identification Number)
14402 FRANKLIN AVENUE
                            TUSTIN, CALIFORNIA 92780
               (Address of principal executive offices) (zip code)

                                   ----------

                              AVIDIA SYSTEMS, INC.
                                 1996 STOCK PLAN
                            (Full title of the plan)

                                   ----------

                               CHARLES S. STRAUCH
                      CHAIRMAN AND CHIEF EXECUTIVE OFFICER
                           PAIRGAIN TECHNOLOGIES, INC.
                              14402 FRANKLIN AVENUE
                            TUSTIN, CALIFORNIA 92780
                                 (714) 832-9922

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

                                   ----------
===============================================================================================================
                                                         Proposed maximum   Proposed maximum
                                          Amount to be    offering price        aggregate         Amount of
Title of securities to be registered     registered(1)      per share(2)   offering price(2)   registration fee
---------------------------------------------------------------------------------------------------------------
Options to Purchase Common Stock            232,564               N/A            N/A                 N/A

Common Stock, $.0005 par value              232,564             $1.78          $413,964              $126
===============================================================================================================
(1) This Registration Statement shall also cover any additional shares of Common
Stock which become issuable under the Avidia Systems, Inc. 1996 Stock Plan by
reason of any stock dividend, stock split, recapitalization or other similar
transaction effected without the receipt of consideration which results in an
increase in the number of the Registrant's outstanding shares of Common Stock.

(2) Calculated solely for purposes of this offering under Rule 457(h) of the
Securities Act of 1933, as amended, on the basis of the weighted average
exercise price of the outstanding options.
2
                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE

            PairGain Technologies, Inc., a Delaware corporation (the
"Registrant"), hereby incorporates by reference into this Registration Statement
the following documents which were previously filed with the Securities and
Exchange Commission (the "SEC"):

      (a)   The Registrant's Annual Report on Form 10-K/A for the year ended
            December 31, 1996 filed pursuant to Section 13(a) of the Securities
            Exchange Act of 1934, as amended (the "1934 Act"), on April 30,
            1997;

      (b)   The Registrant's Current Report on Form 8-K filed with the SEC on
            March 5, 1997;

      (c)   The Registrant's Current Report on Form 8-K/A filed with the SEC on
            April 25, 1997; and

      (d)   The Registrant's Registration Statement No. 0-22202 on Form 8-A
            filed with the SEC on August 6, 1993 pursuant to Section 12 of the
            1934 Act, in which there is described the terms, rights and
            provisions applicable to the Registrant's outstanding Common Stock.

            All reports and definitive proxy or information statements filed by
the Registrant pursuant to Section 13(a), 13(c), 14 or 15(d) of the 1934 Act
after the date of this Registration Statement and prior to the filing of a
post-effective amendment which indicates that all securities offered hereby have
been sold or which deregisters all securities then remaining unsold at the time
of such amendment will be deemed to be incorporated by reference into this
Registration Statement and to be a part hereof from the date of filing of such
documents. Any statement contained in a document incorporated or deemed to be
incorporated by reference herein 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 which also is deemed to
be incorporated by reference herein modifies or supersedes such statement. Any
such 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.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Under Section 145 of the Delaware General Corporation Law, the
Registrant has broad powers to indemnify its directors and officers against
liabilities they may incur in such capacities, including liabilities under the
Securities Act of 1933, as amended (the "1933 Act"). The Registrant's Bylaws
provide that the Registrant will indemnify its directors and officers to the
fullest extent permitted by law and require the Registrant to advance litigation
expenses upon receipt by the Registrant of an undertaking by the director or
officer to repay such advances if it is ultimately determined that the director
or officer is not entitled to indemnification. The Bylaws further provide that
rights conferred under such Bylaws shall not be deemed to be exclusive of any
other right such persons may have or acquire under any bylaw, agreement, vote of
stockholders or disinterested directors or otherwise.

         The Registrant's Restated Certificate of Incorporation provides that,
pursuant to Delaware Law, its directors shall not be liable for monetary damages
for breach of the directors' fiduciary duty of care to the Registrant and its
stockholders. This provision in the Restated Certificate of Incorporation does
not eliminate the duty of care, and, in appropriate circumstances, equitable
remedies such as injunctive or other forms of non-monetary relief will remain
available under Delaware Law. In addition, each director will continue to be
subject to liability for breach of the director's duty of loyalty to the
Registrant or its stockholders, for acts or omissions not in good faith or
involving intentional misconduct or knowing violations of law, for actions
leading to improper personal benefit to the director, and for payment of
dividends or approval of stock repurchases or redemptions that are unlawful
under Delaware Law. The provision also does not affect a director's
responsibilities under any other law, such as the federal securities law or
state or federal environmental laws.

         In addition, the Registrant has entered into agreements to indemnify
its directors and certain of its officers beyond the indemnification provided
for in the Restated Certificate of Incorporation and Bylaws. These agreements

                                      II-1
3
will, among other things, indemnify the Registrant's directors and certain of
its officers for certain expenses (including attorneys' fees), judgments, fines
and settlement amounts incurred by such person in any action or proceeding,
including any action by or in the right of the Registrant, on account of
services as a director or officer of the Registrant, or as a director or officer
of any other company or enterprise to which the person provides services at the
request of the Registrant.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

            Not Applicable.

ITEM 8.  EXHIBITS
Exhibit Number    Exhibit
--------------    -------
4        Instruments Defining Rights of Stockholders. Reference is made to
             Registrant's Registration Statement No. 0-22202 on Form 8-A, which
             is incorporated herein by reference pursuant to Item 3(d) of this
             Registration Statement.
    5        Opinion and consent of Brobeck, Phleger & Harrison LLP.
    23.1     Independent Auditors' Consent - Deloitte & Touche LLP.
    23.2     Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit
             5.
    24       Power of Attorney. Reference is made to page II-4 of this
             Registration Statement.
    99.1     Avidia Systems, Inc. (formerly ATM Products, Inc.) 1996 Stock Plan.
    99.2     Form of Incentive Stock Option.
    99.3     Form of Non-Qualified Stock Option Agreement.
    99.4     Form of Stock Option Assumption Agreement.
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 1933 Act, (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, and (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 (1)(i) and (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 the Registrant pursuant to
Section 13 or Section 15(d) of the 1934 Act that are incorporated by reference
into the Registration Statement; (2) that for the purpose of determining any
liability under the 1933 Act, 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 AVIDIA Systems, Inc. 1996 Stock Plan.

              B. The undersigned Registrant hereby undertakes that, for purposes
of determining any liability under the 1933 Act, each filing of the Registrant's
annual report pursuant to Section 13(a) or Section 15(d) of the 1934 Act that is
incorporated by reference into 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
1933 Act may be permitted to directors, officers or controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the SEC such indemnification is against
public policy as expressed in the 1933 Act and is, therefore, unenforceable. In
the event that 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 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 1933 Act
and will be governed by the final adjudication of such issue.

                                      II-2
4
                                   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 Tustin, State of California, on May 5, 1997.

                                    PAIRGAIN TECHNOLOGIES, INC.

                                    By: /s/ Charles S. Strauch
                                        ------------------------------------
                                        Charles S. Strauch, Chairman,
                                        Chief Executive Officer and Director

                                POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS:

               That the undersigned officers and directors of PairGain
Technologies, Inc., a Delaware corporation, do hereby constitute and appoint
Charles S. Strauch and Charles W. McBrayer, and each of them, the lawful
attorneys-in-fact and agents, with full power and authority to do any and all
acts and things and to execute any and all instruments which said attorneys and
agents, and any one of them, determine may be necessary or advisable or required
to enable said corporation to comply with the Securities Act of 1933, as
amended, and any rules or regulations or requirements of the Securities and
Exchange Commission in connection with this Registration Statement. Without
limiting the generality of the foregoing power and authority, the powers granted
include the power and authority to sign the names of the undersigned officers
and directors in the capacities indicated below to this Registration Statement,
to any and all amendments and supplements to this Registration Statement and to
any and all instruments or documents filed as part of or in conjunction with
this Registration Statement or to amendments or supplements thereof, and each of
the undersigned hereby ratifies and confirms all that said attorneys and agents,
or any one of them, shall do or cause to be done by virtue hereof. This Power of
Attorney may be signed in several counterparts.

               IN WITNESS WHEREOF, each of the undersigned has executed this
Power of Attorney as of the date indicated.

               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/ Charles S. Strauch        Chairman, Chief Executive Officer               May 5, 1997
Charles S. Strauch            and Director (Principal Executive Officer)

/s/ Charles W. McBrayer       Vice President, Finance and Administration,     May 5, 1997
-------------------------     Secretary and Chief Financial Officer
Charles W. McBrayer           (Principal Financial Officer)

/s/ Robert R. Price           Corporate Controller                            May 5, 1997
-------------------------     (Principal Accounting Officer)
Robert R. Price
II-3
5
SIGNATURE                     TITLE                                      DATE
---------                     -----                                      ----
/s/ Howard S. Flagg           President and Director                     May 5, 1997
--------------------------
Howard S. Flagg

/s/ Benedict A. Itri          Executive Vice President,                  May 5, 1997
--------------------------    Chief Technical Officer and Director
Benedict A. Itri              

/s/ Robert A. Hoff            Director                                   May 5, 1997
---------------------------
Robert A. Hoff

/s/ Robert C. Hawk            Director                                   May 5, 1997
----------------------------
Robert C. Hawk

/s/ B. Allen Lay              Director                                   May 5, 1997
----------------------------
B. Allen Lay
II-4
6
                       SECURITIES AND EXCHANGE COMMISSION

                                WASHINGTON, D.C.

                                    EXHIBITS

                                       TO

                                    FORM S-8

                          UNDER SECURITIES ACT OF 1933

                           PAIRGAIN TECHNOLOGIES, INC.
7
                                  EXHIBIT INDEX
Exhibit
Number       Exhibit
------       -------
4        Instruments Defining Rights of Stockholders. Reference is made to
             Registrant's Registration Statement No. 0-22202 on Form 8-A, which
             is incorporated herein by reference pursuant to Item 3(d) of this
             Registration Statement.

    5        Opinion and consent of Brobeck, Phleger & Harrison LLP.

    23.1     Independent Auditors' Consent - Deloitte & Touche LLP.

    23.2     Consent of Brobeck, Phleger & Harrison LLP is contained in Exhibit
             5.

    24       Power of Attorney. Reference is made to page II-4 of this
             Registration Statement.

    99.1     AVIDIA Systems, Inc. (formerly ATM Products, Inc.) 1996 Stock Plan.

    99.2     Form of Incentive Stock Option.

    99.3     Form of Non-Qualified Stock Option Agreement.

    99.4     Form of Stock Option Assumption Agreement.