SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549

                                   FORM 8-K


                                CURRENT REPORT
                    Pursuant to Section 13 or 15(d) of the
                        Securities Exchange Act of 1934


                     February 12, 2003 (February 11, 2003)
               Date of Report (Date of earliest event reported)


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


       Delaware                       000-27273              04-3410558
(State or other jurisdiction         (Commission             (IRS Employer
of incorporation)                    file number)         Identification No.)


                                 220 Mill Road
                             Chelmsford, MA 01824
                   (Address of principal executive offices)
                                  (Zip code)


      Registrant's telephone number, including area code: (978) 250-2900


                                Not Applicable
         (Former name or former address, if changed since last report)


<PAGE>

ITEM 7: FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS

(c)     Exhibits.

    99.1          Press Release of Registrant, dated February 11, 2003,
                  reporting Sycamore Networks, Inc.'s (the "Registrant")
                  second quarter results for the period ending January 25,
                  2003 (furnished and not filed herewith solely pursuant to
                  Item 9).

ITEM 9: REGULATION FD DISCLOSURE

On February 11, 2003, the Registrant reported its second quarter results for
the period ending January 25, 2003.

A copy of the press release issued by the Registrant on February 11, 2003
concerning the foregoing results is furnished herewith as Exhibit 99.1 and is
incorporated herein by reference.

In light of new Securities and Exchange Commission requirements that will be
effective March 28, 2003 concerning the furnishing of additional information
by registrants regarding non-GAAP financial measures and results of operations
or financial condition for completed quarterly or annual periods, the
Registrant is electing to furnish the information for its most recently
completed fiscal quarter under Item 9. The information contained herein and in
the accompanying exhibit shall not be incorporated by reference into any
filing of the Registrant, whether made before or after the date hereof,
regardless of any general incorporation language in such filing. The
information in this report, including the exhibit hereto, shall not be deemed
to be "filed" for purposes of Section 18 of the Securities Exchange Act of
1934, as amended, or otherwise subject to the liabilities of that section or
Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The
furnishing of the information in this report (including the exhibit hereto)
shall not be deemed an admission that such furnishing is required by
Regulation FD or that the information in this report contains material
information that is not otherwise publicly available.

The Registrant provides pro forma net loss and pro forma net loss per share in
the press release as additional information for its operating results. These
measures are not in accordance with, or an alternative for, generally accepted
accounting principles and may be different from pro forma measures used by
other companies. Pro forma net loss has been adjusted to exclude the effects
of stock compensation, payroll tax on stock option exercises, restructuring
charges and related asset impairments, excess inventory charge and losses on
investments. The Registrant's management believes that the presentation of pro
forma net loss and pro forma net loss per share in the press release provides
useful information to investors regarding financial and business trends
relating to its financial condition and results of operations.


<PAGE>


                                  SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

Sycamore Networks, Inc.


/s/ Frances M. Jewels
---------------------------
Frances M. Jewels
Chief Financial Officer
(Duly Authorized Officer and Principal
Financial and Accounting Officer)

Dated: February 12, 2003





<PAGE>


EXHIBIT INDEX

Exhibit               Description
Number

99.1                  Press Release of Registrant, dated February 11, 2003,
                      reporting Registrant's second quarter results for the
                      period ending January 25, 2003.
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SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549

                                   FORM 8-K

                                CURRENT REPORT
                    Pursuant to Section 13 or 15(d) of the
                        Securities Exchange Act of 1934

                     February 12, 2003 (February 11, 2003)
               Date of Report (Date of earliest event reported)

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

       Delaware                       000-27273              04-3410558
(State or other jurisdiction         (Commission             (IRS Employer
of incorporation)                    file number)         Identification No.)

                                 220 Mill Road
                             Chelmsford, MA 01824
                   (Address of principal executive offices)
                                  (Zip code)

      Registrant's telephone number, including area code: (978) 250-2900

                                Not Applicable
         (Former name or former address, if changed since last report)
ITEM 7: FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS

(c)     Exhibits.

    99.1          Press Release of Registrant, dated February 11, 2003,
                  reporting Sycamore Networks, Inc.'s (the "Registrant")
                  second quarter results for the period ending January 25,
                  2003 (furnished and not filed herewith solely pursuant to
                  Item 9).

ITEM 9: REGULATION FD DISCLOSURE

On February 11, 2003, the Registrant reported its second quarter results for
the period ending January 25, 2003.

A copy of the press release issued by the Registrant on February 11, 2003
concerning the foregoing results is furnished herewith as Exhibit 99.1 and is
incorporated herein by reference.

In light of new Securities and Exchange Commission requirements that will be
effective March 28, 2003 concerning the furnishing of additional information
by registrants regarding non-GAAP financial measures and results of operations
or financial condition for completed quarterly or annual periods, the
Registrant is electing to furnish the information for its most recently
completed fiscal quarter under Item 9. The information contained herein and in
the accompanying exhibit shall not be incorporated by reference into any
filing of the Registrant, whether made before or after the date hereof,
regardless of any general incorporation language in such filing. The
information in this report, including the exhibit hereto, shall not be deemed
to be "filed" for purposes of Section 18 of the Securities Exchange Act of
1934, as amended, or otherwise subject to the liabilities of that section or
Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The
furnishing of the information in this report (including the exhibit hereto)
shall not be deemed an admission that such furnishing is required by
Regulation FD or that the information in this report contains material
information that is not otherwise publicly available.

The Registrant provides pro forma net loss and pro forma net loss per share in
the press release as additional information for its operating results. These
measures are not in accordance with, or an alternative for, generally accepted
accounting principles and may be different from pro forma measures used by
other companies. Pro forma net loss has been adjusted to exclude the effects
of stock compensation, payroll tax on stock option exercises, restructuring
charges and related asset impairments, excess inventory charge and losses on
investments. The Registrant's management believes that the presentation of pro
forma net loss and pro forma net loss per share in the press release provides
useful information to investors regarding financial and business trends
relating to its financial condition and results of operations.
SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

Sycamore Networks, Inc.

/s/ Frances M. Jewels
---------------------------
Frances M. Jewels
Chief Financial Officer
(Duly Authorized Officer and Principal
Financial and Accounting Officer)

Dated: February 12, 2003
EXHIBIT INDEX

Exhibit               Description
Number

99.1                  Press Release of Registrant, dated February 11, 2003,
                      reporting Registrant's second quarter results for the
                      period ending January 25, 2003.