Exhibit 5.1     

10100 Santa Monica Boulevard
Seventh Floor
Los Angeles, California 90067
310.552.5000
310.552.5001 Fax
www.kl.com

June 16, 2003

MRV Communications, Inc.
21415 Nordhoff Street
Chatsworth, CA 91311

Re: Registration Statement on Form S-3
Registration for offer and issuance of shares aggregating
up to $20,000,000 aggregate offering price

Dear Sirs:

We have examined the Registration Statement on Form S-3 ( the “Registration Statement”) to be filed with the Securities and Exchange Commission in connection with the registration of shares (the “Shares”) of the Company’s common stock, par value $.0017 per share, aggregating up to $20,000,000 aggregate offering price that may be offered and issued by the Company from time to time.

For purposes of this opinion, we have examined such matters of law and originals, or copies certified or otherwise identified to our satisfaction, of such documents, corporate records and other instruments, as we have deemed necessary. In our examination, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to original documents of all documents submitted to us as certified, photostatic or conformed copies, and the authenticity of the originals of all such latter documents. We have also assumed the due execution and delivery of all documents where due execution and delivery are prerequisites to the effectiveness thereof. We have relied upon certificates of public officials and certificates of officers of the Company for the accuracy of material, factual matters contained therein which were not independently established.

On the basis of the foregoing, subject to effectiveness of the Registration Statement with the SEC (such Registration Statement as amended and finally declared effective, and the form of prospectus contained therein or subsequently filed pursuant to Rule 424 under the Securities Act, being hereinafter referred to as the “Registration Statement”) it is our opinion that the Shares, when authorized by the Board of Directors or a duly appointed committee thereof and issued as contemplated in the Registration Statement will be validly issued, fully paid and non-assessable.

BOSTON • DALLAS • HARRISBURG • LOS ANGELES • MIAMI • NEWARK • NEW YORK • PITTSBURGH • SAN FRANCISCO • WASHINGTON

MRV Communications, Inc.
June 16, 2003
Page 2

We express no opinion as to the applicability or effect of any laws, orders or judgments of any state or jurisdiction other than the substantive laws of the State of Delaware. Further, our opinion is based solely upon existing laws, rules and regulations, and we undertake no obligation to advise you of any changes that may be brought to our attention after the date hereof.

We consent to the use of our name under the caption “Legal Matters” in the Prospectus, constituting part of the Registration Statement, and to the filing of this opinion as an exhibit to the Registration Statement.

By giving you this opinion and consent, we do not admit that we are experts with respect to any part of the Registration Statement or Prospectus within the meaning of the term expert as used in Section 11 of the Securities Act, or the rules and regulations promulgated thereunder by the SEC, nor do we admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act.

Sincerely,

/s/ KIRKPATRICK & LOCKHART LLP

KIRKPATRICK & LOCKHART LLP