Exhibit 99.1

FOR IMMEDIATE RELEASE

CONTACT:

Press Inquiries
Scott Larson
Public Relations
Sycamore Networks, Inc.
978-250-3433
scott.larson@sycamorenet.com Investor Inquiries
Terry Adams
Investor Relations
Sycamore Networks, Inc.
978-250-3460
investor.info@sycamorenet.com

SYCAMORE NETWORKS, INC. REPORTS FOURTH QUARTER AND FISCAL YEAR
2004 FINANCIAL RESULTS

CHELMSFORD, Mass., August 19, 2004 – Sycamore Networks, Inc. (NASDAQ: SCMR), a leader in optical networking, today reported its fourth quarter and fiscal year-end results for the period ended July 31, 2004.

Revenue for the fourth quarter of fiscal 2004 was $14.5 million, compared with $10.9 million for the fourth quarter of fiscal 2003.

Net loss for the fourth quarter of fiscal 2004, on a generally accepted accounting principles (GAAP) basis, was $9.2 million or $(0.03) per share, compared with a net loss of $9.7 million, or $(0.04) per share for the fourth quarter of fiscal 2003. Non-GAAP net loss for the fourth quarter of fiscal 2004, which excludes stock-based compensation and payroll taxes on stock option exercises, was $8.1 million, or $(0.03) per share, compared with a non-GAAP net loss for the fourth quarter of fiscal 2003, which excludes stock-based compensation, payroll taxes on stock option exercises, and a benefit from excess inventory charges and restructuring charges and related asset impairments, was $10.9 million, or $(0.04) per share. The reconciliation between net loss on a GAAP basis and net loss on a non-GAAP basis is provided in a table immediately following the Unaudited Consolidated Statements of Operations included with this release.

Revenue for fiscal 2004 was $44.5 million, compared with $38.3 million for fiscal 2003.

Net loss for fiscal 2004, on a GAAP basis, was $44.9 million or $(0.17) per share, compared with a net loss of $55.1 million or $(0.21) per share for fiscal 2003. Non-GAAP net loss for fiscal 2004, which excludes stock-based compensation and payroll taxes on stock option exercises, was $39.1 million, or $(0.14) per share, compared with a non-GAAP net loss for fiscal 2003, which excludes stock-based compensation, payroll taxes on stock option exercises, and a benefit from excess inventory charges and restructuring charges and related asset impairments, was $52.0 million, or $(0.20) per share. The reconciliation between net loss on a GAAP basis and net loss on a non-GAAP basis is provided in a table immediately following the Unaudited Consolidated Statements of Operations included with this release.

“While we are pleased with our fiscal year 2004 revenue growth, our business continues to be impacted by industry related conditions,” stated Daniel E. Smith, Sycamore’s president and chief executive officer. “In light of these circumstances, we engaged Morgan Stanley to work with us on a review of our strategic and financial alternatives aimed at maximizing shareholder value.”

Conference Call Webcast
Sycamore plans to review its fourth quarter and fiscal year results and discuss its business outlook during a conference call today beginning at 4:30 p.m. EDT. A Webcast of the conference call, along with GAAP reconciliation information, is available to all interested parties on the Sycamore web site located at www.sycamorenet.com under the Investor Relations section. Interested investors are encouraged to log onto the broadcast at least 15 minutes prior to the call. Participating in the call will be Sycamore’s president and chief executive officer, Daniel E. Smith, and chief financial officer, Frances M. Jewels.

About Sycamore Networks
Sycamore Networks, Inc. (NASDAQ: SCMR) develops and markets optical networking products for telecommunications service providers worldwide. The Company’s products enable service providers to easily and cost-effectively transition their existing fiber optic network into an infrastructure that can provision, manage and deliver economic, high-bandwidth services to their customers. For more information, please visit www.sycamorenet.com.

Except for the historical information contained herein, we wish to caution you that certain matters discussed in this news release constitute forward-looking statements that involve risks and uncertainties. Actual results or events could differ materially from those stated or implied in forward-looking statements due to a number of factors, including but not limited to: unfavorable conditions in the telecommunications industry and economy in general; the pursuit of strategic opportunities; the commercial success of the Company’s line of optical networking products; significant cost structure required to support the Company’s strategy; competition; the Company’s reliance on a limited number of customers; the Company’s ability to sell through distribution channels; variation in the Company’s quarterly results; manufacturing and sourcing risks; product performance; conducting business internationally; current and potential litigation; intellectual property rights and disputes; stock market volatility and capital market conditions; and the other factors discussed in the Company’s most recently filed Form 10-Q and the other reports filed by the Company from time to time with the Securities and Exchange Commission. There can be no assurance that any transaction or other corporate action will result from the Company’s review of strategic and financial alternatives. Further, there can be no assurance concerning the type, form, structure, nature, results, timing, or terms and conditions of any such potential transaction, even if such an action does result from this review. The Company disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future results or otherwise.

Use of Non-GAAP Financial Measures

The Company provides non-GAAP financial data in addition to providing financial results in accordance with GAAP. These measures are not in accordance with, or an alternative for GAAP, and may be different from non-GAAP measures used by other companies. The items excluded from non-GAAP results have one or more of the following characteristics: their magnitude and timing is largely outside of the Company’s control; they are unrelated to the ongoing operation of the business in the ordinary course; they are unusual, and the Company does not expect them to occur in the ordinary course of business; or they are non-operational, non-cash expenses involving stock option grants primarily in connection with the Company’s initial public offering and acquisitions.

The non-GAAP financial data is provided to enhance the user’s overall understanding of the Company’s current financial performance and its prospects for the future. Specifically, the Company believes the non-GAAP results provide useful information to both management and investors by excluding certain expense and income items that the Company believes are not indicative of the Company’s core operating results because such charges are associated with past events and are not related to current operations. In addition, since the Company has historically reported non-GAAP results to the investment community, the Company believes the inclusion of non-GAAP numbers provides consistency in its financial reporting. Further, these non-GAAP results are one of the primary indicators management uses for planning and forecasting in future periods. The non-GAAP financial data should be considered in addition to, not as a substitute for or as being superior to, operating losses, cash flows, or other measures of financial performance prepared in accordance with GAAP.

Sycamore Networks, Inc.
Unaudited Condensed Consolidated Balance Sheets
(in thousands)

	July 31, 2004			July 31, 2003
Assets
Current assets:
Cash and cash equivalents	$	152,754		$	250,595
Short-term investments		482,274			421,784
Accounts receivable, net		10,605			10,769
Inventories		4,294			5,117
Prepaids and other current assets		3,611			3,680
Total current assets		653,538			691,945
Property and equipment, net		9,419			14,589
Long-term investments		326,297			323,204
Other assets		1,664			2,890
Total Assets	$	990,918		$	1,032,628
Liabilities and Stockholders' Equity
Deferred revenue	$	7,226		$	2,677
Other current liabilities		15,321			18,350
Restructuring liabilities		12,005			19,086
Total current liabilities		34,552			40,113
Deferred revenue		926			--
Total liabilities		35,478			40,113
Common stock		274			272
Additional paid-in capital		1,740,293			1,733,476
Accumulated deficit		(781,104	)		(736,192	)
Other equity		(4,023	)		(5,041	)
Total stockholders' equity		955,440			992,515
Total Liabilities and Stockholders' Equity	$	990,918		$	1,032,628

Sycamore Networks, Inc.
Unaudited Consolidated Statements of Operations
(in thousands, except per share data)

	Three Months Ended						Year Ended
	July 31, 2004			July 31, 2003			July 31, 2004			July 31, 2003
Revenue	$	14,513		$	10,912		$	44,547		$	38,276
Cost of revenue		8,715			7,260			28,397			33,692
Stock-based compensation and payroll
tax on stock option exercises		167			358			711			1,412
Gross profit		5,631			3,294			15,439			3,172
Operating expenses:
Research and development		11,383			12,399			45,681			52,426
Sales and marketing		4,456			4,865			18,101			19,756
General and administrative		2,273			1,977			7,365			7,237
Stock-based compensation and payroll tax
on stock option exercises:
Research and development		441			460			2,759			3,033
Sales and marketing		204			145			1,001			1,703
General and administrative		279			606			1,334			1,912
Restructuring charges and related asset
impairments		--			(2,254	)		--			(4,447	)
Total operating expenses		19,036			18,198			76,241			81,620
Loss from operations		(13,405	)		(14,904	)		(60,802	)		(78,448	)
Interest and other income, net		4,242			5,171			15,890			23,342
Net loss	$	(9,163	)	$	(9,733	)	$	(44,912	)	$	(55,106	)
Diluted net loss per share	$	(0.03	)	$	(0.04	)	$	(0.17	)	$	(0.21	)
Weighted average shares used in computing
diluted net loss per share		273,564			268,890			272,123			265,702

Sycamore Networks, Inc.
Unaudited Non-GAAP Consolidated Statements of Operations (a)
(in thousands, except per share data)

	Three Months Ended July 31, 2004									Three Months Ended July 31, 2003
	GAAP Results			Adjustments			Non-GAAP Results(a)			GAAP Results			Adjustments			Non-GAAP Results (a)
Revenue	$	14,513		$	--		$	14,513		$	10,912		$	--		$	10,912
Cost of revenue		8,715			--			8,715			7,260			531			7,791
Stock-based compensation and
payroll tax on stock option
exercises		167			(167	)		--			358			(358	)		--
Gross profit		5,631			167			5,798			3,294			(173	)		3,121
Operating expenses:
Research and development		11,383			--			11,383			12,399			--			12,399
Sales and marketing		4,456			--			4,456			4,865			--			4,865
General and administrative		2,273			--			2,273			1,977			--			1,977
Stock-based compensation and
payroll tax on stock option
exercises:
Research and development		441			(441	)		--			460			(460	)		--
Sales and marketing		204			(204	)		--			145			(145	)		--
General and administrative		279			(279	)		--			606			(606	)		--
Restructuring charges and related
asset impairments		--			--			--			(2,254	)		2,254			--
Total operating expenses		19,036			(924	)		18,112			18,198			1,043			19,241
Loss from operations		(13,405	)		1,091			(12,314	)		(14,904	)		(1,216	)		(16,120	)
Interest and other income, net		4,242			--			4,242			5,171			--			5,171
Net loss	$	(9,163	)	$	1,091		$	(8,072	)	$	(9,733	)	$	(1,216	)	$	(10,949	)
Diluted net loss per share	$	(0.03	)				$	(0.03	)	$	(0.04	)				$	(0.04	)
Weighted average shares used in
computing diluted net loss
per share		273,564						273,564			268,890						268,890

(a)   These Unaudited non-GAAP Consolidated Statements of Operations are for informational purposes only and are not presented in accordance with GAAP. The adjustments necessary to provide a direct reconciliation of the non-GAAP to the GAAP basis consolidated statements of operations exclude stock-based compensation, payroll taxes on stock option exercises, and a benefit from excess inventory charges and restructuring charges and related asset impairments.

Sycamore Networks, Inc.
Unaudited Non-GAAP Consolidated Statements of Operations (a)
(in thousands, except per share data)

	Year Ended July 31, 2004									Year Ended July 31, 2003
	GAAP Results			Adjustments			Non-GAAP Results(a)			GAAP Results			Adjustments			Non-GAAP Results (a)
Revenue	$	44,547		$	--		$	44,547		$	38,276		$	--		$	38,276
Cost of revenue		28,397			--			28,397			33,692			531			34,223
Stock-based compensation and
payroll tax on stock option
exercises		711			(711	)		--			1,412			(1,412	)		--
Gross profit		15,439			711			16,150			3,172			881			4,053
Operating expenses:
Research and development		45,681			--			45,681			52,426			--			52,426
Sales and marketing		18,101			--			18,101			19,756			--			19,756
General and administrative		7,365			--			7,365			7,237			--			7,237
Stock-based compensation and
payroll tax on stock option
exercises:
Research and development		2,759			(2,759	)		--			3,033			(3,033	)		--
Sales and marketing		1,001			(1,001	)		--			1,703			(1,703	)		--
General and administrative		1,334			(1,334	)		--			1,912			(1,912	)		--
Restructuring charges and related
asset impairments		--			--			--			(4,447	)		4,447			--
Total operating expenses		76,241			(5,094	)		71,147			81,620			(2,201	)		79,419
Loss from operations		(60,802	)		5,805			(54,997	)		(78,448	)		3,082			(75,366	)
Interest and other income, net		15,890			--			15,890			23,342			--			23,342
Net loss	$	(44,912	)	$	5,805		$	(39,107	)	$	(55,106	)	$	3,082		$	(52,024	)
Diluted net loss per share	$	(0.17	)				$	(0.14	)	$	(0.21	)				$	(0.20	)
Weighted average shares used in
computing diluted net loss
per share		272,123						272,123			265,702						265,702

(a)   These Unaudited non-GAAP Consolidated Statements of Operations are for informational purposes only and are not presented in accordance with GAAP. The adjustments necessary to provide a direct reconciliation of the non-GAAP to the GAAP basis consolidated statements of operations exclude stock-based compensation, payroll taxes on stock option exercises, and a benefit from excess inventory charges and restructuring charges and related asset impairments.