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                                                                     EXHIBIT 5.1





October 5, 2001


MRV Communications, Inc.
20415 Nordhoff Street
Chatsworth, CA 91311

Re:   Registration  Statement on Form S-3
      Registering for resale 2,947,889 shares of common stock
      of MRV Communications, Inc.

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 for resale under the Securities Act of 1933, as
amended, of 2,947,889 shares of common stock, $0.0017 par value (the "Common
Stock"), of MRV Communications, Inc. (the "Company").

We have also examined such other public and corporate documents, certificates,
instruments and corporate records, and such questions of law, as we have deemed
necessary for purposes of expressing an opinion on the matters hereinafter set
forth. In all examinations of documents, instruments and other papers, we have
assumed the genuineness of all signatures on original and certified documents
and the conformity to original and certified documents of all copies submitted
to us as conformed, photostatic or other copies.

On the basis of the foregoing, it is our opinion that the Shares are validly
issued, fully paid and nonassessable shares of Common Stock of the Company.

We express no opinion as to the applicability or effect of any laws, orders or
judgments of any state or jurisdiction other than the Delaware General Corporate
Law. 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.

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MRV Communications, Inc.
October 5, 2001
Page 2


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