<PAGE>   1

      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JULY 28, 1998

                                                     REGISTRATION NO. 333-

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                              Washington, DC 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 of                          (IRS Employer
 incorporation or organization)                      Identification Number)
 
                              14402 FRANKLIN AVENUE
                            TUSTIN, CALIFORNIA 92780
               (Address of principal executive offices) (zip code)

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

                           PAIRGAIN TECHNOLOGIES, INC.
                      1993 STOCK OPTION/STOCK ISSUANCE 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          Proposed
                                                            maximum           maximum            
       Title of securities to be         Amount to be    offering price       aggregate          Aggregate
              registered                 registered(1)    per share(2)    offering price(2)      filing fee
--------------------------------------   -------------- ---------------- ------------------ ------------------
<S>                                     <C>            <C>                <C>                  <C>
1993 Stock Option/Stock Issuance Plan
-------------------------------------
                                         
    Common Stock, $.0005 par value      1,500,000 shares    $13.875          $20,812,500          $6,139.69

==============================================================================================================
</TABLE>

(1) This Registration Statement shall also cover any additional shares of Common
    Stock which become issuable under the 1993 Stock Option/Stock Issuance Plan
    by reason of any stock dividend, stock split, recapitalization or other
    similar transaction effected without the Registrant's receipt of
    consideration which results in an increase in the number of outstanding
    shares of Registrant's 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 average of the high
    and low selling prices per share of Registrant's Common Stock on July 27,
    1998, as reported by the Nasdaq Stock Market(SM).


<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 for the year ended
        December 31, 1997 filed pursuant to Section 13(a) of the Securities
        Exchange Act of 1934, as amended (the "1934 Act") on March 30, 1998, as
        amended on Form 10-K/A filed on April 21, 1998;

        (b) The Registrant's Quarterly Report on Form 10-Q for the fiscal
        quarter ended March 31, 1998, filed with the SEC on May 13, 1998; and

        (c) 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 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 statute or any provision
of any Certificate of Incorporation, 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 their fiduciary duty of care to the Registrant and its


                                      II-1


<PAGE>   3

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 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                                          
  No.                                    Exhibit
-------     ----------------------------------------------------------------------
<S>       <C>
   4        Instruments Defining Rights of Stockholders. Reference is made to
            Registrant's Registration Statement No. 0-22202 on Form 8-A,
            including the exhibits thereto, which is incorporated herein by
            reference pursuant to Item 3(c).
   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     1993 Stock Option/Stock Issuance Plan (Amended and Restated
            as of April 14, 1998).
   99.2*    Form of Notice of Grant.
   99.3*    Form of Stock Option Agreement.
   99.4*    Addendum to Stock Option Agreement - Change in Control.
   99.5*    Addendum to Stock Option Agreement - Financial Assistance.
   99.6*    Addendum to Stock Option Agreement - Special Tax Election.
   99.7*    Addendum to Stock Option Agreement - Limited Stock Appreciation Rights.
   99.8*    Form of Stock Issuance Agreement.
</TABLE>

* Exhibits 99.2 through 99.8 are incorporated herein by reference to Exhibits
  99.2 through 99.8, respectively, to Registrant's Registration Statement No.
  33-96080 on Form S-8 filed with the SEC on August 21, 1995.


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



                                      II-2


<PAGE>   4

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 Registrant's 1993 Stock Option/Stock
Issuance 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 indemnification provisions summarized in Item 6 above 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-3



<PAGE>   5


                                   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 July 28, 1998.

                                        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 Howard S. Flagg, 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               July 28, 1998
--------------------------- and Director (Principal Executive Officer)
Charles S. Strauch          


/s/ Charles W. McBrayer     Senior Vice President, Finance and              July 28, 1998
--------------------------- Administration, Chief Financial Officer
Charles W. McBrayer         and Secretary (Principal Financial Officer)


/s/ Robert R. Price         Vice President and Corporate Controller         July 28, 1998
--------------------------- (Principal Accounting Officer)
Robert R. Price             
</TABLE>


                                      II-4

<PAGE>   6

<TABLE>
<CAPTION>
<S>                        <C>                                             <C>
/s/ Howard S. Flagg         President and Director                          July 28, 1998
---------------------------
Howard S. Flagg


/s/ Benedict A. Itri        Executive Vice President,                       July 28, 1998
--------------------------- Chief Technical Officer and Director
Benedict A. Itri            


/s/ Howard G. Bubb          Director                                        July 28, 1998
---------------------------
Howard G. Bubb


/s/ Robert C. Hawk          Director                                        July 28, 1998
---------------------------
Robert C. Hawk


/s/ Robert C. Hoff          Director                                        July 28, 1998
---------------------------
Robert C. Hoff


/s/ B. Allen Lay            Director                                        July 28, 1998
---------------------------
B. Allen Lay
</TABLE>





                                      II-5




<PAGE>   7

                                  EXHIBIT INDEX
                                  -------------


<TABLE>
<CAPTION>
Exhibit                                          
  No.                                    Exhibit
-------     ----------------------------------------------------------------------
<S>       <C>
   4        Instruments Defining Rights of Stockholders. Reference is made to
            Registrant's Registration Statement No. 0-22202 on Form 8-A,
            including the exhibits thereto, which is incorporated herein by
            reference pursuant to Item 3(c).
   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     1993 Stock Option/Stock Issuance Plan (Amended and Restated
            as of April 14, 1998).
   99.2*    Form of Notice of Grant.
   99.3*    Form of Stock Option Agreement.
   99.4*    Addendum to Stock Option Agreement - Change in Control.
   99.5*    Addendum to Stock Option Agreement - Financial Assistance.
   99.6*    Addendum to Stock Option Agreement - Special Tax Election.
   99.7*    Addendum to Stock Option Agreement - Limited Stock Appreciation Rights.
   99.8*    Form of Stock Issuance Agreement.
</TABLE>

* Exhibits 99.2 through 99.8 are incorporated herein by reference to Exhibits
  99.2 through 99.8, respectively, to Registrant's Registration Statement No.
  33-96080 on Form S-8 filed with the SEC on August 21, 1995.
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 20655}]
{"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": "333-60067", "film-number": "98672815"}, "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 JULY 28, 1998

                                                     REGISTRATION NO. 333-

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                              Washington, DC 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 of                          (IRS Employer
 incorporation or organization)                      Identification Number)
 
                              14402 FRANKLIN AVENUE
                            TUSTIN, CALIFORNIA 92780
               (Address of principal executive offices) (zip code)

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

                           PAIRGAIN TECHNOLOGIES, INC.
                      1993 STOCK OPTION/STOCK ISSUANCE 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          Proposed
                                                            maximum           maximum            
       Title of securities to be         Amount to be    offering price       aggregate          Aggregate
              registered                 registered(1)    per share(2)    offering price(2)      filing fee
--------------------------------------   -------------- ---------------- ------------------ ------------------
1993 Stock Option/Stock Issuance Plan
-------------------------------------
                                         
    Common Stock, $.0005 par value      1,500,000 shares    $13.875          $20,812,500          $6,139.69

==============================================================================================================
(1) This Registration Statement shall also cover any additional shares of Common
    Stock which become issuable under the 1993 Stock Option/Stock Issuance Plan
    by reason of any stock dividend, stock split, recapitalization or other
    similar transaction effected without the Registrant's receipt of
    consideration which results in an increase in the number of outstanding
    shares of Registrant's 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 average of the high
    and low selling prices per share of Registrant's Common Stock on July 27,
    1998, as reported by the Nasdaq Stock Market(SM).
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 for the year ended
        December 31, 1997 filed pursuant to Section 13(a) of the Securities
        Exchange Act of 1934, as amended (the "1934 Act") on March 30, 1998, as
        amended on Form 10-K/A filed on April 21, 1998;

        (b) The Registrant's Quarterly Report on Form 10-Q for the fiscal
        quarter ended March 31, 1998, filed with the SEC on May 13, 1998; and

        (c) 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 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 statute or any provision
of any Certificate of Incorporation, 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 their fiduciary duty of care to the Registrant and its

                                      II-1
3

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 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                                          
  No.                                    Exhibit
-------     ----------------------------------------------------------------------
4        Instruments Defining Rights of Stockholders. Reference is made to
            Registrant's Registration Statement No. 0-22202 on Form 8-A,
            including the exhibits thereto, which is incorporated herein by
            reference pursuant to Item 3(c).
   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     1993 Stock Option/Stock Issuance Plan (Amended and Restated
            as of April 14, 1998).
   99.2*    Form of Notice of Grant.
   99.3*    Form of Stock Option Agreement.
   99.4*    Addendum to Stock Option Agreement - Change in Control.
   99.5*    Addendum to Stock Option Agreement - Financial Assistance.
   99.6*    Addendum to Stock Option Agreement - Special Tax Election.
   99.7*    Addendum to Stock Option Agreement - Limited Stock Appreciation Rights.
   99.8*    Form of Stock Issuance Agreement.
* Exhibits 99.2 through 99.8 are incorporated herein by reference to Exhibits
  99.2 through 99.8, respectively, to Registrant's Registration Statement No.
  33-96080 on Form S-8 filed with the SEC on August 21, 1995.

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

                                      II-2
4

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 Registrant's 1993 Stock Option/Stock
Issuance 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 indemnification provisions summarized in Item 6 above 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-3
5

                                   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 July 28, 1998.

                                        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 Howard S. Flagg, 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               July 28, 1998
--------------------------- and Director (Principal Executive Officer)
Charles S. Strauch          

/s/ Charles W. McBrayer     Senior Vice President, Finance and              July 28, 1998
--------------------------- Administration, Chief Financial Officer
Charles W. McBrayer         and Secretary (Principal Financial Officer)

/s/ Robert R. Price         Vice President and Corporate Controller         July 28, 1998
--------------------------- (Principal Accounting Officer)
Robert R. Price
II-4
6
/s/ Howard S. Flagg         President and Director                          July 28, 1998
---------------------------
Howard S. Flagg

/s/ Benedict A. Itri        Executive Vice President,                       July 28, 1998
--------------------------- Chief Technical Officer and Director
Benedict A. Itri            

/s/ Howard G. Bubb          Director                                        July 28, 1998
---------------------------
Howard G. Bubb

/s/ Robert C. Hawk          Director                                        July 28, 1998
---------------------------
Robert C. Hawk

/s/ Robert C. Hoff          Director                                        July 28, 1998
---------------------------
Robert C. Hoff

/s/ B. Allen Lay            Director                                        July 28, 1998
---------------------------
B. Allen Lay
II-5
7

                                  EXHIBIT INDEX
                                  -------------
Exhibit                                          
  No.                                    Exhibit
-------     ----------------------------------------------------------------------
4        Instruments Defining Rights of Stockholders. Reference is made to
            Registrant's Registration Statement No. 0-22202 on Form 8-A,
            including the exhibits thereto, which is incorporated herein by
            reference pursuant to Item 3(c).
   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     1993 Stock Option/Stock Issuance Plan (Amended and Restated
            as of April 14, 1998).
   99.2*    Form of Notice of Grant.
   99.3*    Form of Stock Option Agreement.
   99.4*    Addendum to Stock Option Agreement - Change in Control.
   99.5*    Addendum to Stock Option Agreement - Financial Assistance.
   99.6*    Addendum to Stock Option Agreement - Special Tax Election.
   99.7*    Addendum to Stock Option Agreement - Limited Stock Appreciation Rights.
   99.8*    Form of Stock Issuance Agreement.
* Exhibits 99.2 through 99.8 are incorporated herein by reference to Exhibits
  99.2 through 99.8, respectively, to Registrant's Registration Statement No.
  33-96080 on Form S-8 filed with the SEC on August 21, 1995.