<PAGE>   1

         As filed with the Securities and Exchange Commission on  July 10, 1997
                                                      Registration No. 333-


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

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

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

                                    FORM S-8

                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933

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

                                     ISOCOR
             (Exact name of Registrant as specified in its charter)

                                   California
         (State or Other Jurisdiction of Incorporation or Organization)

                                   95-4310259
                      (I.R.S. Employer Identification No.)

    3420 Ocean Park Boulevard
     Santa Monica, California                                       90405
(Address of principal executive offices)                         (Zip Code)

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



                             1992 STOCK OPTION PLAN
                            (Full title of the Plan)

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

                                 Andrew De Mari
                      President and Chief Executive Officer
                                     ISOCOR
                            3420 Ocean Park Boulevard
                         Santa Monica, California 90405
                    (Name and Address for Agent For Service)




                                 (310) 581-8100
          (Telephone Number, Including Area Code, of Agent For Service)

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




<PAGE>   2

<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------------------------
                              CALCULATION OF REGISTRATION FEE
-------------------------------------------------------------------------------------------------------
                                                                          Proposed            Proposed
                                                     Maximum             Maximum             Amount of
Title of Securities to     Amount to be          Offering Price      Aggregate Offering    Registration
   be Registered           Registered              Per Share                Price               Fee
<S>                      <C>                      <C>                 <C>                  <C>     
Common Stock,
     no par value        650,774 shares            $2.6720 (2)        $   1,738,868.13     $   526.93

Common Stock,
     no par value        149,226 shares            $2.391 (3)         $     356,799.37     $   108.12

TOTAL                    800,000 shares (1)                           $   2,095,667.50     $   635.05
</TABLE>


(1)      Represents increases in the number of shares of Common Stock reserved
         for issuance upon the exercise of options issued under the Company's
         1992 Stock Option Plan (the "Plan") of 500,000 shares (the "Initial
         Increase") and 300,000 shares (the "Subsequent Increase"). The Initial
         Increase was approved by the Board of Directors of the Company on
         August 26, 1996 and by the shareholders of the Company on October 22,
         1996. The Subsequent Increase was approved by the Board of Directors of
         the Company on March 7, 1997 and by the shareholders of the Company on
         May 15, 1997.

(2)      Computed in accordance with Rule 457(h) under the Securities Act of
         1933, as amended (the "Act") solely for purposes of calculating the
         registration fee. The computation is based on the weighted average
         exercise price of options outstanding under the Plan for which the
         Common Stock issuable upon exercise thereof is being registered hereby.

(3)      Estimated in accordance with Rule 457(h) and 457(c) under the Act
         solely for purposes of calculating the registration fee. The
         computation is based on the closing price of the Company's Common Stock
         as reported on the Nasdaq National Market on July 8, 1997.








<PAGE>   3


PART II: INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3   INFORMATION INCORPORATED BY REFERENCE

         The following documents and information heretofore filed with the
Securities and Exchange Commission are hereby incorporated by reference:

         ITEM 3 (A)

         The Registrant's Annual Report on Form 10-K filed on March 31, 1997
pursuant to Rule 15(d) of the Securities Exchange Act of 1934, as amended (the
"Exchange Act").

         ITEM 3 (B)

         The Registrant's Quarterly Report on Form 10-Q filed on May 15, 1997
pursuant to Rule 13(a) of the Exchange Act.

         All documents subsequently filed by the Registrant pursuant to Sections
13(a) or 15(d) of the Exchange Act, prior to the filing of a post-effective
amendment which indicates that all securities offered have been sold or which
deregisters 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.

         ITEM 3 (C)

         Items 1 and 2 of the Registrant's Registration Statement on Form 8-A
filed on March 5, 1996 pursuant to Section 12 of the Exchange Act.


ITEM 4   DESCRIPTION OF SECURITIES

         Not Applicable.

ITEM 5   INTERESTS OF NAMED EXPERTS AND COUNSEL

         The validity of the Common Stock registered hereby is being passed
upon by Venture Law Group. a Professional Corporation. Certain members of
Venture Law Group, including Elias J. Blawie, Secretary of the Company,
beneficially own, in the aggregate, 8,310 shares of the Company's Common Stock.

ITEM 6   INDEMNIFICATION OF DIRECTORS AND OFFICERS

         The Company has adopted provisions in its Articles of Incorporation
that limit the liability of its directors for monetary damages arising from a
breach of their fiduciary duty as directors to the



<PAGE>   4



fullest extent permitted by the California Corporations Code. Such limitation of
liability does not affect the availability of equitable remedies such as
injunctive relief or recission.

         The Company's Bylaws provide that the Company shall indemnify its
directors and officers to the fullest extent permitted by California law,
including circumstances in which indemnification is otherwise discretionary
under California law. The Company has entered into indemnification agreements
with its directors and officers containing provisions which are, in some
respects, broader than the specific indemnification provisions contained in the
California Corporations Code. The indemnification agreements may require the
Company, among other things, to indemnify its directors and officers against
certain liabilities that may arise by reason of their status or service as
directors or officers (other than liabilities arising from willful misconduct of
a culpable nature), to advance their expenses as incurred as a result of any
proceeding against them as to which they could be indemnified and to obtain
directors' and officers' insurance, if available on reasonable terms. The
Company has obtained such directors' and officers' insurance.

         At present, there is no pending litigation or proceeding involving any
director, officer, employee or agent of the Company where indemnification would
be required or permitted. The Company is not aware of any threatened litigation
or proceeding which might result in a claim for such indemnification.

ITEM 7   EXEMPTION FROM REGISTRATION CLAIMED

         Not Applicable.

ITEM 8   EXHIBITS

     Exhibit
      Number             Document

       4.1             1992 Stock Option Plan and forms of option
                       agreements for use with plan.

       5.1             Opinion of Counsel as to legality of securities
                       being registered.

      23.1             Consent of Counsel  (contained in Exhibit 5.1
                       hereto).

      23.2             Consent of Independent Accountants  (see page 8).

      24.1             Power of Attorney (see page 7).


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 to include any
material information with respect





<PAGE>   5



to the plan of distribution not previously disclosed in the Registration
Statement or any material change to such information in the Registration
Statement.

                  (2) That, for the purpose of determining any liability under
the 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.

                  (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 Act, each filing of the Registrant's annual
report pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and where
applicable each filing of an employee benefit plan's annual report pursuant to
Section 15(d) of the Exchange Act) 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 Act 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 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 Act and will be governed by the final adjudication of
such issue.







<PAGE>   6


                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant, ISOCOR, a corporation organized and existing under the laws of the
State of California, 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 Santa Monica, State of California, on July 10,
1997.

                                        ISOCOR



                                        By:  /s/ Andrew De Mari
                                           -----------------------------------
                                                 Andrew De Mari, President and
                                                 Chief Executive Officer


                                POWER OF ATTORNEY

         KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Andrew De Mari and Janine M. Bushman,
jointly and severally, his or her attorneys-in-fact, each with the power of
substitution, for him or her in any and all capacities, to sign any amendments
to this Registration Statement on Form S-8, and to file the same, with exhibits
thereto and other documents in connection therewith, with the Securities and
Exchange Commission, hereby ratifying and confirming all that each of said
attorneys-in-fact, or his or her substitute or substitutes, may do or cause to
be done by virtue hereof.

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

<TABLE>
<CAPTION>
           Signature                                       Title                                     Date
------------------------------------         ------------------------------------              ---------------
<S>                                          <C>                                                 <C>
                                             President, Chief Executive Officer
      /s/ Andrew De Mari                     and Director (Principal Executive                  July 10, 1997
------------------------------------         Officer)
        (Andrew De Mari)                     

                                             Vice President, Finance and
                                             Administration, Chief Financial
      /s/ Janine M. Bushman                  Officer and Director (Principal                    July 10, 1997
------------------------------------         Financial and Accounting Officer)
         (Janine M. Bushman)                

      /s/ Jean-Michel Barbier                Director                                           July 10, 1997
------------------------------------
         (Jean Michel Barbier)

      /s/ Alexandra Giurgiu                  Director                                           July 10, 1997
------------------------------------
         (Alexandra Giurgiu)

      /s/ G. Bradford Jones                  Director                                           July 10, 1997
------------------------------------
         (G. Bradford Jones)
</TABLE>






<PAGE>   7


                                INDEX TO EXHIBITS
<TABLE>
<CAPTION>
Exhibit                                                                                                     
Number                                                                                                      
------                                                                                                      
<S>         <C>                                                                                             
 4.1        1992 Stock Option Plan and forms of option agreements for use with plan.                        
 5.1        Opinion of Counsel as to legality of securities being registered                                
23.1        Consent of Counsel (contained in Exhibit 5.1 hereto).                                           
23.2        Consent of Independent Auditors.                                                                
24.1        Power of Attorney (see page 6).                                                                 
</TABLE>
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 15515}]
{"company-data": {"conformed-name": "ISOCOR", "cik": "0000879283", "assigned-sic": "7372", "irs-number": "954310259", "state-of-incorporation": "CA", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-31075", "film-number": "97639212"}, "business-address": {"street1": "3420 OCEAN PARK BLVD", "city": "SANTA MONICA", "state": "CA", "zip": "90405"}, "mail-address": {"street2": "3420 OCEAN PARK BLVD SUITE 2010", "city": "SANTA MONICA", "state": "CA", "zip": "904053306"}}
1

         As filed with the Securities and Exchange Commission on  July 10, 1997
                                                      Registration No. 333-

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

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

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

                                    FORM S-8

                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933

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

                                     ISOCOR
             (Exact name of Registrant as specified in its charter)

                                   California
         (State or Other Jurisdiction of Incorporation or Organization)

                                   95-4310259
                      (I.R.S. Employer Identification No.)

    3420 Ocean Park Boulevard
     Santa Monica, California                                       90405
(Address of principal executive offices)                         (Zip Code)

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

                             1992 STOCK OPTION PLAN
                            (Full title of the Plan)

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

                                 Andrew De Mari
                      President and Chief Executive Officer
                                     ISOCOR
                            3420 Ocean Park Boulevard
                         Santa Monica, California 90405
                    (Name and Address for Agent For Service)

                                 (310) 581-8100
          (Telephone Number, Including Area Code, of Agent For Service)

                              ---------------------
2
-------------------------------------------------------------------------------------------------------
                              CALCULATION OF REGISTRATION FEE
-------------------------------------------------------------------------------------------------------
                                                                          Proposed            Proposed
                                                     Maximum             Maximum             Amount of
Title of Securities to     Amount to be          Offering Price      Aggregate Offering    Registration
   be Registered           Registered              Per Share                Price               Fee
Common Stock,
     no par value        650,774 shares            $2.6720 (2)        $   1,738,868.13     $   526.93

Common Stock,
     no par value        149,226 shares            $2.391 (3)         $     356,799.37     $   108.12

TOTAL                    800,000 shares (1)                           $   2,095,667.50     $   635.05
(1)      Represents increases in the number of shares of Common Stock reserved
         for issuance upon the exercise of options issued under the Company's
         1992 Stock Option Plan (the "Plan") of 500,000 shares (the "Initial
         Increase") and 300,000 shares (the "Subsequent Increase"). The Initial
         Increase was approved by the Board of Directors of the Company on
         August 26, 1996 and by the shareholders of the Company on October 22,
         1996. The Subsequent Increase was approved by the Board of Directors of
         the Company on March 7, 1997 and by the shareholders of the Company on
         May 15, 1997.

(2)      Computed in accordance with Rule 457(h) under the Securities Act of
         1933, as amended (the "Act") solely for purposes of calculating the
         registration fee. The computation is based on the weighted average
         exercise price of options outstanding under the Plan for which the
         Common Stock issuable upon exercise thereof is being registered hereby.

(3)      Estimated in accordance with Rule 457(h) and 457(c) under the Act
         solely for purposes of calculating the registration fee. The
         computation is based on the closing price of the Company's Common Stock
         as reported on the Nasdaq National Market on July 8, 1997.
3

PART II: INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3   INFORMATION INCORPORATED BY REFERENCE

         The following documents and information heretofore filed with the
Securities and Exchange Commission are hereby incorporated by reference:

         ITEM 3 (A)

         The Registrant's Annual Report on Form 10-K filed on March 31, 1997
pursuant to Rule 15(d) of the Securities Exchange Act of 1934, as amended (the
"Exchange Act").

         ITEM 3 (B)

         The Registrant's Quarterly Report on Form 10-Q filed on May 15, 1997
pursuant to Rule 13(a) of the Exchange Act.

         All documents subsequently filed by the Registrant pursuant to Sections
13(a) or 15(d) of the Exchange Act, prior to the filing of a post-effective
amendment which indicates that all securities offered have been sold or which
deregisters 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.

         ITEM 3 (C)

         Items 1 and 2 of the Registrant's Registration Statement on Form 8-A
filed on March 5, 1996 pursuant to Section 12 of the Exchange Act.

ITEM 4   DESCRIPTION OF SECURITIES

         Not Applicable.

ITEM 5   INTERESTS OF NAMED EXPERTS AND COUNSEL

         The validity of the Common Stock registered hereby is being passed
upon by Venture Law Group. a Professional Corporation. Certain members of
Venture Law Group, including Elias J. Blawie, Secretary of the Company,
beneficially own, in the aggregate, 8,310 shares of the Company's Common Stock.

ITEM 6   INDEMNIFICATION OF DIRECTORS AND OFFICERS

         The Company has adopted provisions in its Articles of Incorporation
that limit the liability of its directors for monetary damages arising from a
breach of their fiduciary duty as directors to the
4

fullest extent permitted by the California Corporations Code. Such limitation of
liability does not affect the availability of equitable remedies such as
injunctive relief or recission.

         The Company's Bylaws provide that the Company shall indemnify its
directors and officers to the fullest extent permitted by California law,
including circumstances in which indemnification is otherwise discretionary
under California law. The Company has entered into indemnification agreements
with its directors and officers containing provisions which are, in some
respects, broader than the specific indemnification provisions contained in the
California Corporations Code. The indemnification agreements may require the
Company, among other things, to indemnify its directors and officers against
certain liabilities that may arise by reason of their status or service as
directors or officers (other than liabilities arising from willful misconduct of
a culpable nature), to advance their expenses as incurred as a result of any
proceeding against them as to which they could be indemnified and to obtain
directors' and officers' insurance, if available on reasonable terms. The
Company has obtained such directors' and officers' insurance.

         At present, there is no pending litigation or proceeding involving any
director, officer, employee or agent of the Company where indemnification would
be required or permitted. The Company is not aware of any threatened litigation
or proceeding which might result in a claim for such indemnification.

ITEM 7   EXEMPTION FROM REGISTRATION CLAIMED

         Not Applicable.

ITEM 8   EXHIBITS

     Exhibit
      Number             Document

       4.1             1992 Stock Option Plan and forms of option
                       agreements for use with plan.

       5.1             Opinion of Counsel as to legality of securities
                       being registered.

      23.1             Consent of Counsel  (contained in Exhibit 5.1
                       hereto).

      23.2             Consent of Independent Accountants  (see page 8).

      24.1             Power of Attorney (see page 7).

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 to include any
material information with respect
5

to the plan of distribution not previously disclosed in the Registration
Statement or any material change to such information in the Registration
Statement.

                  (2) That, for the purpose of determining any liability under
the 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.

                  (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 Act, each filing of the Registrant's annual
report pursuant to Section 13(a) or Section 15(d) of the Exchange Act (and where
applicable each filing of an employee benefit plan's annual report pursuant to
Section 15(d) of the Exchange Act) 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 Act 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 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 Act and will be governed by the final adjudication of
such issue.
6

                                   SIGNATURES

         Pursuant to the requirements of the Securities Act of 1933, the
Registrant, ISOCOR, a corporation organized and existing under the laws of the
State of California, 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 Santa Monica, State of California, on July 10,
1997.

                                        ISOCOR

                                        By:  /s/ Andrew De Mari
                                           -----------------------------------
                                                 Andrew De Mari, President and
                                                 Chief Executive Officer

                                POWER OF ATTORNEY

         KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below constitutes and appoints Andrew De Mari and Janine M. Bushman,
jointly and severally, his or her attorneys-in-fact, each with the power of
substitution, for him or her in any and all capacities, to sign any amendments
to this Registration Statement on Form S-8, and to file the same, with exhibits
thereto and other documents in connection therewith, with the Securities and
Exchange Commission, hereby ratifying and confirming all that each of said
attorneys-in-fact, or his or her substitute or substitutes, may do or cause to
be done by virtue hereof.

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated.
Signature                                       Title                                     Date
------------------------------------         ------------------------------------              ---------------
President, Chief Executive Officer
      /s/ Andrew De Mari                     and Director (Principal Executive                  July 10, 1997
------------------------------------         Officer)
        (Andrew De Mari)                     

                                             Vice President, Finance and
                                             Administration, Chief Financial
      /s/ Janine M. Bushman                  Officer and Director (Principal                    July 10, 1997
------------------------------------         Financial and Accounting Officer)
         (Janine M. Bushman)                

      /s/ Jean-Michel Barbier                Director                                           July 10, 1997
------------------------------------
         (Jean Michel Barbier)

      /s/ Alexandra Giurgiu                  Director                                           July 10, 1997
------------------------------------
         (Alexandra Giurgiu)

      /s/ G. Bradford Jones                  Director                                           July 10, 1997
------------------------------------
         (G. Bradford Jones)
7

                                INDEX TO EXHIBITS
Exhibit                                                                                                     
Number                                                                                                      
------
4.1        1992 Stock Option Plan and forms of option agreements for use with plan.                        
 5.1        Opinion of Counsel as to legality of securities being registered                                
23.1        Consent of Counsel (contained in Exhibit 5.1 hereto).                                           
23.2        Consent of Independent Auditors.                                                                
24.1        Power of Attorney (see page 6).