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



                                 August 3, 2004
                Date of Report (Date of earliest event reported)



                                CIENA Corporation
             (Exact name of registrant as specified in its charter)


          Delaware                  0-21969                  23-2725311
(State or other jurisdiction (Commission File No.)  (IRS Employer Identification
     of incorporation)                                          No.)

                1201 Winterson Road, Linthicum, Maryland 21090
               (Address of principal executive offices) (Zip Code)



               Registrant's telephone number, including area code:
                                 (410) 865-8500



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


                             Exhibit Index on Page 2



TABLE OF CONTENTS Item 12. Results of Operations and Financial Condition - ------------------------------------------------------- SIGNATURES - ----------- EXHIBIT INDEX - ------------- EX-99.1 Text of Press Release - ----------------------------- The information in this Report, including the exhibit, is furnished under Item 12 of Form 8-K and, pursuant to General Instruction B.6 thereunder, is not "filed" for the purposes of Section 18 of the Securities Exchange Act of 1934 or incorporated by reference into the filings of the registrant under the Securities Act of 1933. ITEM 12. RESULTS OF OPERATIONS AND FINANCIAL CONDITION On August 3, 2004, CIENA Corporation issued a press release announcing its preliminary financial results for the fiscal quarter ended July 31, 2004. The text of the press release is furnished as Exhibit 99.1 to this Report. ITEM 7. FINANCIAL STATEMENTS AND EXHIBITS. (c) Exhibits -- The following exhibit is furnished as part of this Report: Exhibit 99.1 -- Text of Press Release issued by CIENA Corporation, dated August 3, 2004.

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. CIENA CORPORATION Dated: August 3, 2004 By: /s/ Russell B. Stevenson, Jr. --------------------------------------- Senior Vice President, General Counsel and Secretary

                                                                    Exhibit 99.1

        CIENA Announces Preliminary Third Quarter 2004 Results

     LINTHICUM, Md.--(BUSINESS WIRE)--Aug. 3, 2004--

 Due to Successful Cost Control and Expense Reduction Efforts, Expects
    Non-GAAP Loss Per Share Within Previous Guidance Range Despite
            Expectations of Lower-than-Anticipated Revenue

    CIENA(R) Corporation (NASDAQ:CIEN), a leading global provider of
intelligent service creation and delivery solutions, today announced
it expects to report fiscal third quarter revenue for the period ended
July 31, 2004, of approximately $75 million, representing slight
sequential revenue growth and year-over-year revenue growth of
approximately 9 percent.
    The Company stated previously it anticipated revenue growth of up
to as much as 30 percent from fiscal second quarter revenue of $74.7
million. The Company attributed the difference between current
expectations and its previous expectations to an ongoing environment
of uncertainty resulting in cautious spending and deployment delays by
its large service provider customers, including a deceleration of
DSL-related orders in North America.
    Due in part to its ongoing, company-wide cost-reduction efforts,
CIENA anticipates lower-than-expected research and development, sales
and marketing and general and administrative expenses for the period.
CIENA expects that under Generally Accepted Accounting Principles
(GAAP), its loss per share for the fiscal third quarter will be
reported in a range of $0.24 to $0.26.
    In evaluating the operating performance of its business, CIENA's
management excludes certain charges or credits that are required by
GAAP. These items, such as deferred stock compensation costs,
amortization of intangible assets, in-process research and development
costs, accelerated amortization of leasehold improvements,
restructuring costs, gain or loss on equity investments, and recovery
and settlement of sales, use and export tax liabilities, share one or
more of the following characteristics: they are unusual, and CIENA
does not expect them to recur in the ordinary course of its business;
they do not involve the expenditure of cash; they are unrelated to the
ongoing operation of the business in the ordinary course; or their
magnitude and timing is largely outside of the Company's control.
    Exclusive of such items in its fiscal third quarter, CIENA expects
its non-GAAP loss per share will be reported in a range of $0.07 to
$0.08, consistent with the Company's previously offered guidance of a
loss in the range of $0.06 to $0.08 per share, despite the
lower-than-anticipated revenue expectations in the quarter.
    The Company expects to end its fiscal third quarter with
approximately $1.3 billion in cash, cash equivalents and investments.
    CIENA intends to report third quarter 2004 results on Thursday,
August 19, 2004, prior to the open of the financial markets.

    Live Conference Call/Web Broadcast

    In conjunction with this announcement, CIENA will host a
discussion about its preliminary fiscal third quarter results with
investors and financial analysts on Tuesday, August 3, 2004 at 5:00
p.m. (Eastern). To access the call, listeners should dial (913)
981-4900 at least 10 minutes prior to the scheduled start time. No
access number or password is required. A limited number of dial-in
lines will be available. Alternatively, the discussion will be
broadcast live via CIENA's homepage at www.CIENA.com. A replay of the
call will be available by approximately 8:00 p.m. Tuesday by dialing
(719) 457-0820. Use access code: 190579 for the replay only. An
archived version of the discussion will be available shortly following
the conclusion of the live broadcast on the Investor Relations page of
CIENA's website at: www.CIENA.com/investors.

    NOTE TO INVESTORS

    This press release contains certain forward-looking statements
based on current expectations, forecasts and assumptions that involve
risks and uncertainties. These statements are based on information
available to the Company as of the date hereof; and CIENA's actual
results could differ materially from those stated or implied, due to
risks and uncertainties associated with its business, which include
the risk factors disclosed in its Report on Form 10-Q, which CIENA
filed with the Securities and Exchange Commission on May 20, 2004.
Forward-looking statements include statements regarding CIENA's
expectations, beliefs, intentions or strategies regarding the future
and can be identified by forward-looking words such as "anticipate,"
"believe," "could," "estimate," "expect," "intend," "may," "should,"
"will," and "would" or similar words. Forward-looking statements in
this release include: CIENA expects to report revenue for the fiscal
quarter ended July 31, 2004, of approximately $75 million; CIENA
anticipates lower-than-expected research and development, sales and
marketing and general and administrative expenses for the period;
CIENA expects that under Generally Accepted Accounting Principles
(GAAP), its loss per share for the fiscal third quarter will be
reported in a range of $0.24 to $0.26; CIENA expects its non-GAAP loss
per share will be reported in a range of $0.07 to $0.08; and CIENA
expects to end its fiscal third quarter with approximately $1.3
billion in cash, cash equivalents and investments. CIENA assumes no
obligation to update the information included in this press release,
whether as a result of new information, future events or otherwise.

    ABOUT CIENA

    CIENA Corporation delivers innovative network solutions to the
world's largest service providers, cable operators and enterprises,
increasing the cost-efficiency of current services while enabling the
creation of new carrier-class data services built upon the existing
network infrastructure. Additional information about CIENA can be
found at www.ciena.com.


    CONTACT: CIENA Corporation
             Investor Contacts:
             Suzanne DuLong or Jessica Towns
             (888) 243-6223
             email: ir@ciena.com
              or
             Press Contacts:
             Aaron Graham or Nicole Anderson
             (877) 857-7377
             email: pr@ciena.com