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EXHIBIT 5.01

    September 10, 2001

Niku Corporation
350 Convention Way
Redwood City, California 94063

Ladies and Gentlemen:

    At your request, we have examined the Registration Statement on Form S-8 (the "Registration Statement") to be filed by Niku Corporation, a Delaware corporation (the "Company"), with the Securities and Exchange Commission (the "Commission") on or about September 10, 2001 in connection with the registration under the Securities Act of 1933, as amended, of an aggregate 1,000,000 shares of the Company's Common Stock (the "Shares") subject to issuance by the Company upon exercise of stock options granted under the Non-Plan Stock Option Agreements between the Company and Richard LaBarbera dated December 4, 2000 (the "Stock Option Agreements").

    In rendering this opinion, we have examined the following:

(1)

the Company's Amended and Restated Certificate of Incorporation filed with the Delaware Secretary of State on March 3, 2000;



(2)

the Company's Amended and Restated Bylaws, amended as of March 6, 2000;



(3)

the minutes of meetings of the Board of Directors that are contained in the Company's minute books relating to approval of the Stock Option Agreements and that have been provided to us by the Company;



(4)

the Registration Statement, together with the exhibits filed as a part thereof;



(5)

the Prospectus prepared in connection with the Registration Statement;



(6)

a certificate from the Company's transfer agent verifying the number of the Company's issued and outstanding shares of capital stock as of July 30, 2001 and a summary report of currently outstanding options and warrants to purchase the Company's capital stock that was prepared by the Company and dated July 28, 2001, verifying the number of such issued and outstanding securities; and



(7)

a management certificate addressed to us and dated of even date herewith executed by the Company containing certain factual and other representations.

    In our examination of documents for purposes of this opinion, we have assumed, and express no opinion as to, the genuineness of all signatures on original documents, the authenticity and completeness of all documents submitted to us as originals, the conformity to originals and completeness of all documents submitted to us as copies, the legal capacity of all persons executing the same, the lack of any undisclosed termination, modification, waiver or amendment to any document reviewed by us and the due authorization, execution and delivery of all documents where due authorization, execution and delivery are prerequisites to the effectiveness thereof. We have also assumed that the certificates representing the Shares will be, when issued, properly signed by authorized officers of the Company or their agents.

    As to matters of fact relevant to this opinion, we have relied solely upon our examination of the documents referred to above and have assumed the current accuracy and completeness of the information obtained from records and documents referred to above. We have made no independent investigation or other attempt to verify the accuracy of any of such information or to determine the existence or non-existence of any other factual matters; however, we are not aware of any facts that would cause us to believe that the opinion expressed herein is not accurate.

    We are admitted to practice law in the State of California, and we render this opinion only with respect to, and express no opinion herein concerning the application or effect of the laws of any

jurisdiction other than, the existing laws of the United States of America, of the State of California and, with respect to the validity of corporate action and the requirements for the issuance of stock, of the State of Delaware.

    In connection with our opinion expressed below, we have assumed that, at or prior to the time of the delivery of the Shares, the Registration Statement will have been declared effective under the Securities Act of 1933, as amended, that the registration will apply to such Shares and will not have been modified or rescinded and that there will not have occurred any change in law affecting the validity or enforceability of the Shares.

    Based upon the foregoing, it is our opinion that the 1,000,000 Shares subject to issuance by the Company upon exercise of stock options granted under the Stock Option Agreements, when issued and sold in accordance with the Stock Option Agreements, and in the manner referred to in the Prospectus associated with the Registration Statement, will be validly issued, fully paid and nonassessable.

    We consent to the use of this opinion as an exhibit to the Registration Statement and further consent to all references to us, if any, in the Registration Statement, the Prospectus constituting a part thereof and any amendments thereto. This opinion speaks only as of its date and we assume no obligation to update this opinion should circumstances change after the date hereof. This opinion is intended solely for use in connection with the offer and sale of the Shares and is not to be relied upon for any other purpose.

Very truly yours,

FENWICK & WEST LLP

By: /s/ Jeffrey R. Vetter      Jeffrey R. Vetter, a partner

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EXHIBIT 5.01