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                                                                   EXHIBIT 10.26

THIS NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED
(THE "SECURITIES ACT"), OR ANY STATE SECURITIES LAWS AND MAY NOT BE OFFERED,
SOLD, PLEDGED OR OTHERWISE TRANSFERRED OR DISPOSED OF UNLESS AND UNTIL THIS NOTE
IS REGISTERED UNDER THE SECURITIES ACT AND APPLICABLE STATE SECURITIES LAWS OR
AN EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE.

                                 PROMISSORY NOTE

$2,000,000.00                                                     March 29, 2002

         FOR VALUE RECEIVED, the undersigned, CELL ROBOTICS INTERNATIONAL, INC.,
a Colorado corporation ("MAKER"), promises to pay to the order of DIPL. ING.
OTON TISCH ("PAYEE"), at Apartado 76949, Caracas 1070 Venezuela (or such other
place as Payee may from time to time designate), the sum of Two Million and
No/100 Dollars ($2,000,000.00), or so much as may have been advanced hereunder,
together with interest on the unpaid principal balance from time to time
outstanding at a rate per annum equal to eight percent (calculated on the basis
of the actual number of days elapsed, but computed as if each calendar year
consisted of 365 days). Capitalized terms used but not defined herein shall have
the meanings ascribed to those terms in that certain Loan Agreement, dated
August 2, 2001, by and between Payee and Maker. Notwithstanding anything to the
contrary contained herein, no provision of this Note shall require the payment
or permit the collection of interest in excess of the Maximum Legal Rate.

         Interest on this Note shall accrue from the date hereof. All principal
of and interest on this Note shall be paid on April 1, 2004.

         All past due principal of and accrued interest on this Note shall bear
interest from maturity (stated, by acceleration, or otherwise) until
indefeasibly paid in full at the lesser of ten percent and the Maximum Legal
Rate.

         1. ADVANCES. At any time and from time to time after the date hereof,
Maker may request Payee to make an advance under this Note, provided that the
amount so requested, plus any amounts previously advanced by Payee under this
Note shall not exceed an aggregate principal amount of $2,000,000. Upon any such
request, Payee, in his discretion, may advance to Maker in immediately available
funds a principal amount equal to the amount so requested. Unless otherwise
agreed by Payee, no advance under this Note shall be made following the earlier
of (i) April 1, 2004 or (ii) the occurrence of an Event of Default and the
notice by Payee of its intent to exercise its remedies pursuant to Section 3
hereof.

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         2. OPTIONAL PREPAYMENTS. Maker, at any time and from time to time, may
prepay the unpaid principal amount of this Note in whole or in part without
premium; provided, however, that any such optional prepayment shall be applied
to accrued but unpaid interest and then to the unpaid principal amount of this
Note.

         3. EVENTS OF DEFAULT AND REMEDIES. Upon or at any time after the
occurrence of an Event of Default, the principal amount of this Note together
with all interest accrued thereon shall, at the option of Payee and without
notice or demand by Payee, become at once due and payable and Maker shall
forthwith pay to Payee, in addition to any and all sums and charges due, the
entire principal of and accrued and unpaid interest on this Note plus reasonable
attorneys' fees and expenses, if the same are collected by or through an
attorney at law. Upon or at any time after the occurrence of any Event of
Default, Payee shall have and may exercise, at its election, from time to time
any and all rights and remedies available to a secured party under the UCC, in
addition to any and all other rights and remedies afforded by this Note, at law,
in equity or otherwise, including, without limitation, (a) declaring the entire
unpaid balance of this Note, or any part thereof, immediately due and payable,
whereupon it shall be due and payable; (b) reducing any claim to judgment; and
(c) bringing suit or other proceedings before any appropriate court either for
specific performance of any covenant or condition contained in this Note or in
aid of the exercise of any right granted to Payee in this Note.

         4. CUMULATIVE RIGHTS. No failure on the part of Payee to exercise, and
no delay by Payee in exercising, any right or remedy hereunder shall operate as
a waiver thereof, nor shall any single or partial exercise of any right or
remedy hereunder preclude any other or further exercise thereof or the exercise
of any other right or remedy. The rights and remedies herein provided are
cumulative and are in addition to any other rights and remedies provided by
Applicable Law or otherwise.

         5. WAIVER. Maker, and each surety, endorser, guarantor and other party
ever liable for the payment of any sum of money payable on this Note, jointly
and severally waive demand, presentment, protest, notice of nonpayment, notice
of intention to accelerate, notice of acceleration, notice of protest and any
and all lack of diligence or delay in the collection or filing of suit hereon
which may occur; agree that their liability on this Note shall not be affected
by any renewal or extension in the time of payment hereof, by any indulgences,
or by any release or change in any security for the payment of this Note; and
hereby consent to any and all renewals, extensions, indulgences, releases or
changes hereof or hereto, regardless of the number of such renewals, extensions,
indulgences, releases or changes.

         6. NO ORAL AGREEMENTS. THIS NOTE (ALONG WITH THE OTHER LOAN DOCUMENTS)
REPRESENTS THE FINAL AGREEMENT BETWEEN MAKER AND PAYEE AND MAY NOT BE
CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS
OF MAKER AND PAYEE. THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN MAKER AND
PAYEE.

         7. GOVERNING LAW. THIS NOTE SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE DOMESTIC LAWS OF THE STATE OF NEW MEXICO WITHOUT GIVING
EFFECT TO ANY CHOICE OR CONFLICT OF LAW PROVISION OR RULE (WHETHER OF THE STATE

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OF NEW MEXICO OR ANY OTHER JURISDICTION) THAT WOULD CAUSE THE APPLICATION OF THE
LAWS OF ANY JURISDICTION OTHER THAN THE STATE OF NEW MEXICO. Any legal action or
proceeding with respect to this Note shall be brought in any New Mexico state or
federal court sitting in Bernalillo County, New Mexico, and, by execution and
delivery of this Note, Maker hereby accepts for itself and in respect of its
property, generally and unconditionally, the jurisdiction of the aforesaid
courts. Maker hereby irrevocably waives any objection, including, without
limitation, any objection to the laying of venue or based on the grounds of
FORUM NON CONVENIENS, which it may now or hereafter have to the bringing of any
such action or proceeding in such respective jurisdictions.

         8. SEVERABILITY. Any term or provision of this Note that is invalid or
unenforceable in any situation in any jurisdiction shall not affect the validity
or enforceability of the remaining terms and provisions hereof or the validity
or enforceability of the offending term or provision in any other situation or
in any other jurisdiction.

         9. SUCCESSION AND ASSIGNMENT. This Note shall be binding upon and inure
to the benefit of Maker and Payee and their respective successors and permitted
assigns. Payee may not assign either this Note or any of its rights, interests
or obligations hereunder without the prior written approval of the Maker.

         IN WITNESS WHEREOF, the undersigned has executed this Note as of the
day and year first above written.

                                            CELL ROBOTICS INTERNATIONAL, INC.

                                            By:  /s/ Ronald K. Lohrding, Ph.D.
                                                 -------------------------------
                                                 Ronald K. Lohrding, Ph.D.
                                                 President and CEO

ACKNOWLEDGED AND AGREED THIS 29TH DAY
OF MARCH, 2002:

By:/s/ Oton Tisch
   -----------------------------------
       Oton Tisch

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                                                                   EXHIBIT 10.27

                        FIRST AMENDMENT TO LOAN AGREEMENT

This First Amendment to Loan Agreement (this "Amendment"), dated and effective
as of March 29, 2002 is entered into between Cell Robotics International, Inc.
(the "Borrower") and Oton Tisch ("Lender").

                             PRELIMINARY STATEMENTS

         A. Borrower and Lender have entered into that certain Loan Agreement
(herein so called) dated August 2, 2001.

         B. Borrower has executed and delivered to Lender a promissory note
dated the date hereof in the face amount of $2,000,000 (the "March 2002 Note").

         C. In connection with the issuance of the March 2002 Note, Borrower and
Lender desire to amend Article 1 of the Loan Agreement as set forth herein.

NOW, THEREFORE, the parties agree as follows:

                                    AGREEMENT

1.       The definition of Indebtedness contained in Article 1 of the Loan
         Agreement is hereby amended and restated in its entirety as follows:

              "'Indebtedness' shall mean all indebtedness, liabilities and
              obligations owing, arising, due or payable from the Borrower to
              the Lender under the Note or that certain Promissory Note dated
              March 29, 2002 in the face amount of $2,000,000 executed by
              Borrower and payable to the order of Lender."

2.       Except as expressly modified by this Amendment, all terms and
         conditions of the Loan Agreement remain in full force and effect.

CELL ROBOTICS INTERNATIONAL, INC.

By:      /s/ Ronald K. Lohrding                     By:  /s/ Oton Tisch
         -----------------------------------             -----------------------
         Ronald K. Lohrding                                  Oton Tisch
         President and Chief Executive Officer

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