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                                                                     EXHIBIT 5.1

                ROBINSON SILVERMAN PEARCE ARONSOHN & BERMAN LLP

                          1290 AVENUE OF THE AMERICAS

                            NEW YORK, NEW YORK 10104

                                October 18, 2000

barnesandnoble.com inc.
76 Ninth Avenue, 11th Floor
New York, New York 10011

     Re: barnesandnoble.com inc.
         Registration Statement on Form S-4

Ladies and Gentlemen:

     We have acted as counsel to barnesandnoble.com inc., a Delaware corporation
(the "Company"), in connection with the Company's Registration Statement on Form
S-4 (the "Registration Statement") filed today with the Securities and Exchange
Commission (the "Commission") under the Securities Act of 1933, as amended (the
"Securities Act"), relating to the proposed issuance of up to 13,500,000 shares
(the "Shares") of the Class A common stock, par value $0.001 per share, of the
Company (the "Company Common Stock") in connection with the merger of
Fatbrain.com, Inc., a Delaware corporation ("Fatbrain") with and into the
Company pursuant to the terms of an Agreement and Plan of Merger, dated as of
September 13, 2000 (the "Merger Agreement"), by and between the Company and
Fatbrain.

     This opinion is furnished by us, as counsel to the Company, in accordance
with the requirements of Item 601(b)(5) of Regulation S-K under the Securities
Act.

     In connection with this opinion, we have examined originals or copies,
certified or otherwise identified to our satisfaction, of (i) the Registration
Statement, (ii) the Merger Agreement, (iii) the Amended and Restated Certificate
of Incorporation and Amended and Restated Bylaws of the Company, each as
currently in effect; and (iv) certain resolutions adopted by the Board of
Directors of the Company relating to the issuance of the Shares and certain
related matters and (v) a specimen certificate evidencing the Company Common
Stock. We also have examined originals or copies, certified or otherwise
identified to our satisfaction, of such records of the Company and such
agreements, certificates of public officials, certificates of officers or other
representatives of the Company or others, and such other documents, certificates
and records as we have deemed necessary or appropriate as a basis for the
opinions set forth herein.

     In our examination, we have assumed the genuineness of all signatures, the
legal capacity of natural persons, the authenticity of all documents submitted
to us as originals, the conformity to original documents of all documents
submitted to us as certified, conformed or photostatic copies and the
authenticity of the originals of such documents. In making our examination of
documents executed or to be executed, we have assumed that the parties thereto,
other than the Company, had or will have the power, corporate or other, to enter
into and perform all obligations thereunder and have also assumed the due
authorization by all requisite action, corporate or other, and execution and
delivery by such parties of such documents and the validity and binding effect
thereof on such parties. As to any facts material to the opinions expressed
herein that we have not independently established or verified, we have relied
upon statements and representations of officers and other representatives of the
Company and others. We have also assumed that the certificates evidencing the
Shares will conform to the specimen examined by us.

     Members of our firm are admitted to the bar of the State of New York and do
not express any opinion as to the laws of any jurisdiction other than the
General Corporation Law of the State of Delaware.
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     Based upon and subject to the foregoing, we are of the opinion that the
Shares have been duly authorized and, when delivered in exchange for shares of
Fatbrain common stock pursuant to the terms of the Merger Agreement, will be
validly issued, fully paid and nonassessable.

     We hereby consent to the filing of this opinion with the Commission as an
exhibit to the Registration Statement. We also consent to the reference to our
firm under the caption "Legal Matters" in the prospectus forming a part of the
Registration Statement. In giving this consent, we do not thereby admit that we
are within the category of persons whose consent is required under Section 7 of
the Securities Act, or the rules and regulations of the Commission promulgated
thereunder.

                                    Very truly yours,

                                    /s/ ROBINSON SILVERMAN PEARCE ARONSOHN &
                                    BERMAN LLP