As filed with the Securities and Exchange Commission on April 7 , 2003
                                                           Registration No. 333-
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                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549

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                                   FORM S-8

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                            REGISTRATION STATEMENT
                                     UNDER
                          THE SECURITIES ACT OF 1933

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                            SYCAMORE NETWORKS, INC.
            (Exact name of registrant as specified in its charter)

            Delaware                                     04-3410558
(State or other jurisdiction of             (I.R.S. Employer Identification No.)
 incorporation or organization)

                220 Mill Road, Chelmsford, Massachusetts 01824
              (Address of Principal Executive Offices) (Zip Code)

           Sycamore Networks, Inc. 1999 Employee Stock Purchase Plan
                           (Full title of the plan)

                                Daniel E. Smith
                     President and Chief Executive Officer
                            Sycamore Networks, Inc.
                                 220 Mill Road
                             Chelmsford, MA 01824
                                (978) 250-2900
                     (Name, Address and Telephone Number,
                  Including Area Code, of Agent for Service)

                                  Copies to:
                          Margaret A. Brown, Esquire
                   Skadden, Arps, Slate, Meagher & Flom LLP
                               One Beacon Street
                             Boston, MA 02108-3194

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                        CALCULATION OF REGISTRATION FEE
========================================================================================================================
                                                           Proposed maximum       Proposed maximum         Amount of
     Title of securities to be         Amount to be            offering               aggregate          Registration
            registered                registered (1)     price per share (2)     offering price (2)           fee
- ------------------------------------------------------------------------------------------------------------------------
                                                                                                     
Common Stock, $.001 par value(1)       1,228,092 shares         $3.03                   $3,721,118.76            $301.04
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(1)      Represents shares of common stock issuable under the Sycamore
         Networks, Inc. 1999 Employee Stock Purchase Plan. In addition to the
         number of shares of Common Stock of Registrant shown in the table
         above, pursuant to Rule 416(c) of the Securities Act of 1933, as
         amended (the "Securities Act"), this Registration Statement covers an
         indeterminate number of shares that may be issuable under the
         Sycamore Networks, Inc. 1999 Employee Stock Purchase Plan pursuant to
         the anti-dilution provisions of such Plan.

(2)      Calculated pursuant to Rule 457(c) and (h) under the Securities Act,
         solely for the purpose of computing the registration fee and based on
         the average of the high and low prices of the Common Stock on March
         31, 2003, as reported by the Nasdaq National Market.

                                    PART I

             INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

         The documents containing the information specified in Part I will be
sent or given to employees as specified by Rule 428(b)(1). Such documents are
not being filed with the Securities and Exchange Commission (the "Commission")
either as part of this Registration Statement or as prospectuses or prospectus
supplements pursuant to Rule 424. Such documents and the documents
incorporated by reference in this Registration Statement pursuant to Item 3 of
Part II of this Form, taken together, constitute a prospectus that meets the
requirements of Section 10(a) of the Securities Act.

                                    PART II

              INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.       Incorporation of Documents by Reference

         The Registrant is subject to the informational and reporting
requirements of Sections 13(a), 14 and 15(d) of the Securities Exchange Act of
1934, as amended (the "Exchange Act"), and in accordance therewith files
reports, proxy statements and other information with the Commission. The
following documents, which are on file with the Commission, are incorporated
in this Registration Statement by reference:

         (1)      Annual Report on Form 10-K for the year ended July 31, 2002;

         (2)      Current Report on Form 8-K furnished on February 12, 2003;

         (3)      Quarterly Reports on Form 10-Q for the quarters ended
                  October 26, 2002 and January 25, 2003; and

         (4)      All other reports filed by the Registrant pursuant to
                  Section 13(a) or 15(d) of the Exchange Act, since July 31,
                  2002; and

         (5)      The description of Common Stock contained in the Rule
                  424(b)(3) Prospectus filed on August 16, 2000.

         All documents subsequently filed by the Registrant pursuant to
Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act, prior to the filing
of a post-effective amendment which indicates that all shares of Common Stock
offered hereby have been sold or which deregisters all shares of Common Stock
then remaining unsold, shall be deemed to be incorporated by reference herein
and to be part hereof from the date of the 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 other subsequently filed document which also is or is deemed to be
incorporated by reference herein modifies or supersedes such statement. Any
statement so modified or superseded shall not be deemed, except as so modified
or superseded, to constitute a part of this Registration Statement.

         Certain documents previously filed by the Registrant incorporated by
reference herein include non-GAAP financial measures. The Registrant hereby
provides the following information to supplement the non-GAAP financial
measures included in such filings.

         The Form 10-K for the fiscal year ended July 31, 2002 (the "Form
10-K"), discussed the cost of revenue for fiscal 2001 and fiscal 2000 as a
percentage of revenue within the "Cost of Revenue" section of Management's
Discussion and Analysis of Financial Condition and Results of Operations. Cost
of revenue, excluding stock compensation expense, was disclosed as
representing 84% of total revenue in fiscal 2001 and 53% of total revenue in
fiscal 2000. Including stock compensation expense of $3.1 million and $1.4
million in fiscal 2001 and fiscal 2000, respectively, cost of revenue
represented 85% and 54% of revenue in fiscal 2001 and fiscal 2000,
respectively. In addition, cost of revenue excluding stock compensation
expense was disclosed as 53% of revenue in the first two quarters of each of
fiscal 2001 and fiscal 2000. Including stock compensation expense of $2.1
million and $0.6 million in each of the first six months of fiscal 2001 and
fiscal 2000, respectively, cost of revenue represented 54% of revenue in each
of the first six months of fiscal 2001 and fiscal 2000.

         The Form 10-K and the Form 10-Q for the quarterly period ended
October 26, 2002 (the "Form 10-Q"), discussed the percentage of revenue that
gross profit represented in fiscal 2002, fiscal 2001 and the first half of
fiscal 2001 within the risk factor entitled "We Expect Gross Margins To Remain
At Reduced Levels In The Near Term," regarding the Registrant's expectations
of its gross margin in the near term. As stated in the Form 10-K and the Form
10-Q, after excluding the effect of special charges and stock compensation
expense, gross profit was 9% of revenue in fiscal 2002, as compared to 38% of
revenue in fiscal 2001 and 47% of revenue in the first half of fiscal 2001.
The special charges and stock compensation expense were $91.6 million and $1.8
million, respectively, in fiscal 2002, $84.0 million and $3.1 million,
respectively, in fiscal 2001 and $0 and $2.1 million, respectively, in the
first half of fiscal 2001. After including the effect of special charges and
stock compensation expense, gross profit (loss) was (134%), 15% and 46% of
revenue in fiscal 2002, fiscal 2001 and the first half of fiscal 2001,
respectively.

Item 4. Description of Securities

Not applicable.

Item 5. Interests of Named Experts and Counsel

Not applicable.

Item 6.           Indemnification of Directors and Officers

         Article SEVENTH of the Registrant's Amended and Restated Certificate
of Incorporation, as amended (the "Restated Certificate"), provides that no
director of the Registrant shall be personally liable for monetary damages for
any breach of fiduciary duty as a director, except to the extent that the
Delaware General Corporation Law prohibits the elimination or limitation of
liability of directors for breach of fiduciary duty.

         Article EIGHTH of the Restated Certificate provides that a director
or officer of the Registrant (a) shall be indemnified by the Registrant
against all expenses (including attorneys' fees), judgments, fines and amounts
paid in settlement incurred in connection with any litigation or other legal
proceeding (other than an action by or in the right of the Registrant) brought
against him by virtue of his position as a director or officer of the
Registrant if he acted in good faith and in a manner he reasonably believed to
be in, or not opposed to, the best interests of the Registrant, and, with
respect to any criminal action or proceeding, had no reasonable cause to
believe his conduct was unlawful and (b) shall be indemnified by the
Registrant against all expenses (including attorneys' fees) and amounts paid
in settlement incurred in connection with any action by or in the right of the
Registrant brought against him by virtue of his position as director or
officer of the Registrant if he acted in good faith and in a manner he
reasonably believed to be in, or not opposed to, the best interests of the
Registrant, except that no indemnification shall be made with respect to any
matter as to which such person shall have been adjudged to be liable to the
Registrant, unless the Court of Chancery of Delaware determines that, despite
such adjudication but in view of all of the circumstances, he is entitled to
indemnification of such expenses. Notwithstanding the foregoing, to the extent
that a director or officer has been successful, on the merits or otherwise,
including, without limitation, the dismissal of an action without prejudice,
he is required to be indemnified by the Registrant against all expenses
(including attorneys' fees) incurred in connection therewith. Expenses shall
be advanced to a director or officer at his request, unless it is determined
that he did not act in good faith and in a manner he reasonably believed to be
in, or not opposed to, the best interests of the Registrant, and, with respect
to any criminal action or proceeding had reasonable cause to believe that his
conduct was unlawful, provided that he undertakes to repay the amount advanced
if it is ultimately determined that he is not entitled to indemnification for
such expenses.

         Indemnification is required to be made unless the Registrant
determines that the applicable standard of conduct required for
indemnification has not been met. In the event of a determination by the
Registrant that the director or officer did not meet the applicable standard
of conduct required for indemnification, or if the Registrant fails to make an
indemnification payment within 60 days after such payment is claimed by such
person, such person is permitted to petition the court to make an independent
determination as to whether such person is entitled to indemnification. As a
condition precedent to the right of indemnification, the director or officer
must give the Registrant notice of the action for which indemnity is sought
and the Registrant has the right to participate in such action or assume the
defense thereof.

         Article EIGHTH of the Restated Certificate further provides that the
indemnification provided therein is not exclusive, and provides that in the
event that the Delaware General Corporation Law is amended to expand the
indemnification permitted to directors or officers, the Registrant must
indemnify those persons to the fullest extent permitted by such law as so
amended.

         Section 145 of the Delaware General Corporation Law provides that a
corporation has the power to indemnify a director, officer, employee or agent
of the corporation and certain other persons serving at the request of the
corporation in related capacities against amounts paid and expenses incurred
in connection with an action or proceeding to which he is a party or is
threatened to be made a party by reason of such position, if such person shall
have acted in good faith and in a manner he reasonably believed to be in or
not opposed to the best interests of the corporation, and, in any criminal
proceeding, if such person had no reasonable cause to believe his conduct was
unlawful; provided that, in the case of actions brought by or in the right of
the corporation, no indemnification shall be made with respect to any matter
as to which such person shall have been adjudged to be liable to the
corporation unless and only to the extent that the adjudicating court
determines that such indemnification is proper under the circumstances.

         The Registrant has entered into indemnification agreements with each
of its director and officers. These agreements may require the Registrant,
among other things, to indemnify directors and officers against certain
liabilities that may arise by reason of their status or service as directors
and officers and to advance their expenses incurred as a result of any
proceeding against them as to which they could be indemnified.

         The Registrant has obtained liability insurance for its officers and
directors, which insures such officers and directors against certain
liabilities.

Item 7. Exemption from Registration Claimed

Not applicable.

Item 8.           Exhibits

         The Exhibit Index immediately preceding the exhibits is incorporated
herein by reference.

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 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.

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

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

         b. The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
Registrant's annual report pursuant to Section 13(a) or 15(d) of the
Securities Exchange Act of 1934 (and, where applicable, each filing of an
employee benefit plan's annual report pursuant to Section 15(d) of the
Securities Exchange Act of 1934) that is incorporated by reference in the
Registration Statement shall be deemed to be a new Registration Statement
relating to the securities offered therein, and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof.

         c. Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the Registrant pursuant to the foregoing provisions, or otherwise,
the Registrant has been advised that in the opinion of the Securities and
Exchange Commission such indemnification is against public policy as expressed
in the 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.

                                  SIGNATURES

         Pursuant to the requirements of the Securities Act, 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 Town of Chelmsford, Commonwealth of Massachusetts, on this
7th day of April, 2003.


                                     SYCAMORE NETWORKS, INC.

                                     By: /s/ Daniel E. Smith
                                        ________________________________________
                                          Daniel E. Smith
                                          President and Chief Executive Officer


                       Power of Attorney and Signatures

         We, the undersigned officers and directors of Sycamore Networks,
Inc., hereby severally constitute Gururaj Deshpande, Daniel E. Smith and
Frances M. Jewels, and each of them individually, our true and lawful
attorneys with full power to them, and each of them singly, to sign for us and
in our names in the capacities indicated below, the Registration Statement on
Form S-8 filed herewith and any and all subsequent amendments to said
Registration Statement, and generally to do all such things in our names and
behalf in our capacities as officers and directors to enable Sycamore
Networks, Inc. to comply with all requirements of the Securities and Exchange
Commission, hereby ratifying and confirming our signatures as they may be
signed by said attorneys, or any of them, to said Registration Statement and
any and all amendments thereto.

         Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed below by the following persons in the capacities
indicated on this 7th day of April, 2003.



                                            
             /s/ Gururaj Deshpande
         -------------------------------        Chairman of the Board of Directors
               Gururaj Deshpande

            /s/ Daniel E. Smith
         ------------------------------         President, Chief Executive Officer and Director
               Daniel E. Smith                  (Principal Executive Officer)

            /s/ Frances M. Jewels
         ------------------------------         Chief Financial Officer, Vice President, Finance and
              Frances M. Jewels                 Administration, Secretary and Treasurer
                                                (Principal Financial and Accounting Officer)
            /s/ Timothy Barrows
         ------------------------------         Director
               Timothy Barrows

            /s/ Paul J. Ferri
         ------------------------------         Director
                Paul J. Ferri

            /s/ John W. Gerdelman
         ------------------------------         Director
              John W. Gerdelman

            /s/ Paul W. Chisholm
         ------------------------------         Director
               Paul W. Chisholm






                                 Exhibit Index


     Exhibit
      Number                         Description
    
       3.1         Amended and Restated Certificate of Incorporation of the Company (2)
       3.2         Certificate of Amendment to the Amended and Restated Certificate of Incorporation
                   of the Company (2)
       3.3         Certificate of Amendment to the Amended and Restated Certificate of Incorporation
                   of the Company (3)
       3.4         Amended and Restated By-Laws of the Company (2)
       4.1         Specimen common stock certificate (1)
       4.2         See Exhibits 3.1, 3.2, 3.3 and 3.4 for provisions of the Certificate of Incorporation and
                   By-Laws of the Registrant defining the rights of holders of common stock of the
                   Company (2)(3)
       4.3         Second Amended and Restated Investor Rights Agreement dated February 26, 1999,
                   as amended by Amendment No. 1 dated as of July 23, 1999 (1)
       4.4         Amendment No. 2 dated as of August 5, 1999 to the Second Amended and Restated
                   Investor Rights Agreement dated February 26, 1999 (2)
       4.5         Amendment No. 3 dated as of September 20, 1999 to the Second Amended and
                   Restated Investor Rights Agreement dated February 26, 1999 (2)
       4.6         Amendment No. 4 dated as of February 11, 2000 to the Second Amended and
                   Restated Investor Rights Agreement dated February 26, 1999 (2)
       5.1         Opinion of Skadden, Arps, Slate, Meagher & Flom LLP
       23.1        Consent of Skadden, Arps, Slate, Meagher & Flom LLP (included in Exhibit 5.1)
       23.2        Consent of PricewaterhouseCoopers LLP (Boston, Massachusetts)
       24.1        Power of Attorney (included in the signature pages of this Registration Statement)

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(1)      Incorporated by reference to Sycamore Networks, Inc.'s Registration Statement on Form S-1
         (Registration Statement No. 333-84635).
(2)      Incorporated by reference to Sycamore Networks Inc.'s Registration Statement on Form S-1
         (Registration Statement No. 333-30630).
(3)      Incorporated by reference to Sycamore Networks, Inc.'s Quarterly Report on Form 10-Q for the
         quarterly period ended January 27, 2001 filed with the Commission on March 13, 2001.