EXHIBIT 10.15
                                                                   -------------

                   AMEMDMENT TO REGISTRATION RIGHTS AGREEMENT

     This Amendment to Registration Rights Agreement (the "Amendment") is dated
as of January 25, 2006 by and among Intraop Medical Corporation, a Nevada
corporation (the "Company") and the Purchasers named below (each, a "Purchaser"
and together, the "Purchasers").

     WHEREAS, the Company and certain of the Purchasers entered into a
Registration Rights Agreement dated as of August 31, 2005 (the "August Rights
Agreement").

     WHEREAS, the Company and certain of the Purchasers entered into
Registration Rights Agreement dated as of October 25, 2005, on substantially the
same terms as the August Rights Agreement (the "October Rights Agreement" and
together with the August Rights Agreement, the "Rights Agreements").

     WHEREAS, Section 2 of the Rights Agreements requires the Company to file a
registration statement with the Securities and Exchange Commission registering
securities issued by the Company and held by the Purchasers on the timetable set
forth therein.

     WHEREAS, the Company and the Purchasers have agreed to modify the
registration obligations of the Company under the Rights Agreements, as set
forth below.

     NOW, THEREFORE, BE IT RESOLVED, for good and valuable consideration and
intending to be legally bound, the parties hereto agree as follows:

     1. Defined Terms. Capitalized terms used and not otherwise defined herein
that are defined in the Rights Agreements shall have the meanings given such
terms in the Rights Agreements.

     2. Amendment to Section 1 (Definitions) - Definition of Effectiveness Date.
The definition of "Effectiveness Date" set forth in Section 1 of the Rights
Agreements is hereby amended in its entirety to provide as follows:

          "Effectiveness Date" means, (i) with respect to the initial
     Registration Statement required to be filed hereunder, March 31, 2006, (ii)
     with respect to any subsequent Registration Statement referred to in
     Section 2(a), as amended, thirty (30) calendar days following the Filing
     Date for such subsequent Registration Statement and (iii) with respect to
     any additional Registration Statements which may be required pursuant to
     Section 3(c), the 120th calendar day following the date on which the
     Company first knows, or reasonably should have known, that such additional
     Registration Statement is required hereunder; provided, however, in the


                                       1
<PAGE>

     event the Company is notified by the Commission that one of the above
     Registration Statements will not be reviewed or is no longer subject to
     further review and comments, the Effectiveness Date as to such Registration
     Statement shall be the fifth Trading Day following the date on which the
     Company is so notified if such date precedes the dates required above."

     3. Amendment to Section 1 (Definitions) - Definition of Filing Date. The
definition of "Filing Date" set forth in Section 1 of the Rights Agreements is
hereby amended in its entirety to provide as follows:

          "Filing Date" means (i) with respect to the initial Registration
     Statement required hereunder, January 27, 2006, (ii) with respect to any
     subsequent Registration Statement referred to in Section 2(a), as amended,
     five (5) Trading Days following the date that the immediately preceding
     Registration Statement filed by the Company with the Commission is declared
     effective by the Commission and (iii) with respect to any additional
     Registration Statements which may be required pursuant to Section 3(c), the
     30th day following the date on which the Company first knows, or reasonably
     should have known that such additional Registration Statement is required
     hereunder."

     4. Amendment to Section 2(a) (Shelf Registration). Section 2(a) of the
Rights Agreements is hereby amended in its entirety to provide as follows:

          "(a) On or prior to the Filing Date, the Company shall prepare and
     file with the Commission a "Shelf" Registration Statement covering the
     resale of ten million (10,000,000) shares of Registrable Securities on such
     Filing Date for an offering to be made on a continuous basis pursuant to
     Rule 415. Thereafter, (i) within five (5) Trading Days of the date that
     such initial Registration Statement is declared effective by the Commission
     the Company shall file a second "Shelf" Registration Statement to register
     fifteen million (15,000,000) shares of Registrable Securities for an
     offering to be made on a continuous basis pursuant to Rule 415, (ii) within
     five (5) Trading Days of the date that such second Registration Statement
     is declared effective by the Commission the Company shall file a third
     "Shelf" Registration Statement to register twenty two million five hundred
     thousand (22,500,000) shares of Registrable Securities for an offering to
     be made on a continuous basis pursuant to Rule 415 and (iii) to the extent
     required, within five (5) Trading Days of the date that such third
     Registration Statement is declared effective by the Commission the Company
     shall file a fourth "Shelf" Registration Statement to register such
     additional number of Registrable Securities for an offering to be made on a
     continuous basis pursuant to Rule 415 such that the aggregate number of
     Registrable Securities registered by the Company pursuant to the Rights
     Agreements equals 130% of the Registrable Securities on the Filing Date.


                                       2
<PAGE>

     The Registrable Securities included in each such Registration Statement
     shall be allocated among the Purchasers on a pro rata basis (calculated
     based upon the number of Registrable Securities held by such Purchaser
     divided by the total number of Registrable Securities held by all
     Purchasers). Each Registration Statement shall be on Form S-3 (except if
     the Company is not then eligible to register for resale the Registrable
     Securities on Form S-3, in which case such registration shall be on another
     appropriate form in accordance herewith) and shall contain (unless
     otherwise directed by the Holders) substantially the "Plan of Distribution"
     attached hereto as Annex A. Subject to the terms of this Agreement, the
     Company shall use its best efforts to cause each Registration Statement to
     be declared effective under the Securities Act as promptly as possible
     after the filing thereof, and, with respect to the initial Registration
     Statement, prior to the applicable Effectiveness Date, and shall use its
     best efforts to keep each such Registration Statement continuously
     effective under the Securities Act until all Registrable Securities covered
     by such Registration Statements have been sold or may be sold without
     volume restrictions pursuant to Rule 144(k) as determined by the counsel to
     the Company pursuant to a written opinion letter to such effect, addressed
     and acceptable to the Company's transfer agent and the affected Holders
     (the "Effectiveness Period"). The Company shall telephonically request
     effectiveness of a Registration Statement as of 5:00 pm Eastern Time on a
     Trading Day. The Company shall immediately notify the Holders via facsimile
     of the effectiveness of a Registration Statement on the same Trading Day
     that the Company telephonically confirms effectiveness with the Commission,
     which shall be the date requested for effectiveness of a Registration
     Statement. The Company shall, by 9:30 am Eastern Time on the Trading Day
     after the Effective Date (as defined in the Purchase Agreement), file a
     Form 424(b)(5) with the Commission. Failure to so notify the Holder within
     1 Trading Day of such notification shall be deemed an Event under Section
     2(b)."

     5. Amendment to Section 6(f) (Amendments and Waivers; Additional
Purchasers). The first sentence of Section 6(f) of the Rights Agreements is
hereby amended to read as follows:

          "The provisions of this Agreement, including the provisions of this
     sentence, may not be amended, modified or supplemented, and waivers or
     consents to departures from the provisions hereof may not be given, unless
     the same shall be in writing and signed by the Company and Holders of at
     least 75% of the then outstanding Registrable Securities, provided however,
     that no amendment that would adversely affect a Holder shall be effective
     unless consented to in writing by such Holder."


                                       3
<PAGE>

     6. Penalties; Events of Default.

     (a) The Purchasers hereby agree that any liquidated damages or penalty
interest payable by the Company pursuant to Section 2(b)(i) of the Rights
Agreements (without giving effect to this Amendment) with respect to filing a
Registration Statement on or prior to the Filing Date are hereby waived and
extinguished.

     (b) The Company and Purchasers party to the August Rights Agreement hereby
agree that liquidated damages payable by the Company pursuant to Section
2(b)(iv) of the August Rights Agreement with respect to the Registration
Statement not being declared effective by the Commission by its Effectiveness
Date, shall accrue commencing March 31, 2006 and shall be payable by the Company
in accordance with Section 2(b) of the August Rights Agreement.

     (c) The Company and Purchasers party to the October Rights Agreement hereby
agree that, notwithstanding the definition of "Effectiveness Date," as amended,
liquidated damages payable by the Company pursuant to Section 2(b)(iv) of the
October Rights Agreement with respect to the Registration Statement not being
declared effective by the Commission by its Effectiveness Date, shall accrue and
be payable commencing April 30, 2006 if, on such date, fifty percent (50%) or
more of the Registrable Securities under the October Rights Agreement have not
been registered pursuant to a Registration Statement declared effective by the
Commission. Such liquidated damages shall continue to accrue and be payable
until all Registrable Securities under the October Rights Agreement have been
registered pursuant to a Registration Statement declared effective by the
Commission.

     (d) Any Event of Default (as defined in the 7% convertible debentures or
10% senior secured debentures issued by the Company to the Purchasers, as
applicable) arising from the Company's breach of Section 2 of the Rights
Agreements is hereby waived, subject to the Company's compliance with Section 2
of the Rights Agreements, as amended.

     7. Priority of Registration. Registrable Securities registered in each
Registration Statement filed by the Company pursuant to Section 2(a) of the
Rights Agreements shall be allocated among the Purchasers on a pro rata basis,
based upon the number of Registrable Securities owned by each such Purchaser.
The Company shall register Registrable Securities in the following order: (i)
shares issuable upon conversion of Debentures, (ii) shares issuable upon
exercise of Long Term Warrants and (iii) shares issuable upon exercise of Short
Term Warrants (provide that holders of 10% senior secured debentures shall be
entitled to register shares underlying warrants in lieu of shares underlying
Debentures). For purposes of this Amendment, "Debenture," "Long Term Warrants"
and "Short Term Warrants" shall have the meanings set forth in the Securities
Purchase Agreement entered into by the Company and the respective Purchasers
named therein. Notwithstanding anything herein to the contrary, any Purchaser
may re-prioritize the registration of its Registrable Securities within its
pro-rata allocation of registration rights upon written instructions from such
Purchaser.

     8. Short Term Warrant - Effective Date. For purposes of determining the
Termination Date of the Short Term Warrants, the "Effective Date" for a Short
Term Warrant shall be the date that all shares underlying such Short Term
Warrant have been registered on a Registration Statement declared effective by
the Commission.


                                       4
<PAGE>

     9. Registration of Other Securities. Until such time as the Registration
Statements described in Section 2(a) of the Rights Agreements, as amended, have
been declared effective by the Commission, registering all of the Registrable
Securities held by the Purchasers, the Company shall not file any other
registration statement registering shares for its own account or for others
under the Securities Act. Notwithstanding the foregoing, the Company may
register with the Commission securities under Form S-4 or Form S-8 or their then
equivalents relating to equity securities to be issued solely in connection with
any acquisition of any entity or business or equity securities issuable in
connection with stock option or other employee benefit plans.

     10. Effective Date of Amendment. This Amendment shall be effective when
executed by holders of seventy five percent (75%) of the outstanding Registrable
Securities under each of the August Rights Agreement and the October Rights
Agreement.

     11. Issuance of Shares to parties to the August Rights Agreement. In
consideration of the parties to the August Rights Agreement agreeing to enter
into this Amendment, the Company shall issue an aggregate of 112,500 shares of
its common stock to such parties (45,000 shares to Bushido Master Capital Fund,
L.P.; 22,500 shares to Gamma Opportunity Capital Partners, LP Class A; 22,500
shares to Gamma Opportunity Capital Partners, LP Class C and 22,500 shares to
Samir Financial, L.L.C.) (each such party an "August Party" and such shares the
"August Shares") promptly after execution of this Amendment by the August
Parties. The August Shares issued pursuant to this Section 11 shall be deemed to
be "Registrable Securities" under the August Rights Agreement. Unless instructed
in writing by an August Party to the contrary, the August Shares relating to
such August Party shall be included on the second Registration Statement filed
relating to the Registrable Securities and have priority over such August
Party's registration of shares underlying the Long Term Warrants provided that
such inclusion shall not increase such August Party's pro-rata allocation of
registration rights as set forth in Section 7 above.

     12. Reference to the Agreement. On and after the effective date of this
Amendment, each reference in the August Rights Agreement or the October Rights
Agreement to "the Agreement," "this Agreement," "hereunder" and "hereof" or
words of like import shall refer to the August Rights Agreement or the October
Rights Agreement, (as applicable) as amended by this Amendment. The August
Rights Agreement and the October Rights Agreement, as amended by this Amendment,
are and shall continue to be in full force and effect and are hereby in all
respects ratified and confirmed.

     13. Governing Law. All questions concerning the construction, validity,
enforcement and interpretation of this Amendment shall be governed by and
construed and enforced in accordance with the internal laws of the State of New
York, without regard to the principles of conflicts of law thereof.


                                       5
<PAGE>

     14. Counterparts. This Amendment may be executed in any number of
counterparts, each of which when so executed shall be deemed to be an original
and, all of which taken together shall constitute one and the same Agreement. In
the event that any signature is delivered by facsimile transmission, such
signature shall create a valid binding obligation of the party executing (or on
whose behalf such signature is executed) the same with the same force and effect
as if such facsimile signature were the original thereof.


                                       6
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have executed this Amendment as of
the date first above written.


                                  THE COMPANY:
                                  -----------


                                  INTRAOP MEDICAL CORPORATION


                                  By:    /s/ Donald A. Goer
                                      ------------------------------------------
                                      Name: Donald A. Goer
                                      Title: Chief Executive Officer & President


                                  THE PURCHASERS:
                                  --------------


                                  BUSHIDO MASTER CAPITAL FUND, LP

                                  By:    /s/ Christopher Rossman
                                      ------------------------------------------
                                      Name: Christopher Rossman
                                      Title: Managing Director


                                  GAMMA OPPORTUNITY CAPITAL
                                   PARTNERS, LP CLASS A

                                  By:    /s/ Jonathan Knight
                                      ------------------------------------------
                                      Name: Jonathan Knight
                                      Title: President/Director


                                  GAMMA OPPORTUNITY CAPITAL
                                   PARTNERS, LP CLASS C

                                  By:    /s/ Jonathan Knight
                                      ------------------------------------------
                                      Name: Jonathan Knight
                                      Title: President/Director


                                       7
<PAGE>


                                  SAMIR FINANCIAL, L.L.C.

                                  By:    /s/ Mohammed H. Mirza
                                      ------------------------------------------
                                      Name: Mohammed H. Mirza
                                      Title: Manager


                                  REGENMACHER HOLDINGS, LTD.

                                  By:    /s/ Jonathan Knight
                                      ------------------------------------------
                                      Name: Jonathan Knight
                                      Title: Director


                                  ABS SOS-PLUS PARTNERS LTD.

                                  By:    /s/ Jonathan Knight
                                      ------------------------------------------
                                      Name: Jonathan Knight
                                      Title: President


                                  DOLPHIN OFFSHORE PARTNERS, L.P.

                                  By:    /s/ Peter E. Salas
                                      ------------------------------------------
                                      Name: Peter E. Salas
                                      Title: Authorized Signatory


                                  ALPHA CAPITAL AG

                                  By:
                                      ------------------------------------------
                                      Name:
                                      Title:


                                  CRESTVIEW CAPITAL MASTER, LLC

                                  By:    /s/ Stewart R. Flink
                                      ------------------------------------------
                                      Name: Stewart R. Flink
                                      Title: Member


                                       8
<PAGE>


                                  MAGNETAR CAPITAL MASTER FUND, LTD.

                                  By: Magnetar Financial, LLC
                                      Its: Investment Manager

                                  By:    /s/ Paul Smith
                                      ------------------------------------------
                                      Name: Paul Smith
                                      Title: General Counsel



                                       9