[KANA LETTERHEAD]

Exhibit 10.05

[KANA LETTERHEAD]

September 29, 2005

Re: Amendment to Registration Rights Agreement

Ladies and Gentlemen:

Reference hereby is made to the Registration Rights Agreement dated as of dated June 25, 2005 (the “Registration Rights Agreement”; terms defined in the Registration Rights Agreement and not otherwise defined herein are used herein as therein defined), by and among Kana Software, Inc. (the “Company”) and the Investors named therein (the “Investors”).

In connection with the issuance of securities to the Investors pursuant to the Common Stock and Warrant Purchase Agreement (the “Purchase Agreement”), dated June 25, 2005, by and among the Company and the Investors, the Company and the Investors hereby agree to amend the Registration Rights Agreement so that:

(i) the “Filing Date” shall mean on or prior to the date which is not later than the twentieth (20th) day following the filing of the Company’s Quarterly Report on Form 10-Q for the six months ended June 30, 2005; and

(ii) the “Registration Deadline” shall mean and refer to January 27, 2006.

Except as expressly set forth herein, this letter shall not operate as a waiver or an amendment of any terms, conditions, rights, or privileges of the Investors under the Registration Rights Agreement. Except as expressly set forth herein, all other terms of the Registration Rights Agreement remain in full force and effect.

Please acknowledge your agreement with the foregoing by signing where indicated below and returning an executed counterpart of this letter to the undersigned.

Very truly yours,

[Signatures Continue on Following Page]

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Agreed and Acknowledged:

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