EXHIBIT 10.66

Dutchess Capital Management, Ltd.

50 Commonwealth Ave.

Suite 2

Boston, MA 02116

July 20, 2007

DNAPrint Genomics, Inc.

1621 West University Parkway

Sarasota, FL  34243

Ladies and Gentlemen:

The parties acknowledge the accuracy of the following facts:

1.

DNAPrint Genomics, Inc. ("DNAPrint") is a party to an Investment Agreement dated
March 30, 2007, with Dutchess Private Equities Fund, Ltd. as successor in
interest to Dutchess Private Equities Fund, L.P. and Dutchess Private Equities
Fund, II, L.P. (collectively, "Dutchess").

2.

In addition, DNAPrint has borrowed money from Dutchess pursuant to a series of
promissory notes (collectively, the "Notes").

3.

Pursuant to the Notes, DNAPrint has issued to Dutchess certain incentive
debentures (collectively the "Incentive Debentures").

4.

DNAPrint has established a wholly-owned subsidiary, DNAPrint Pharmaceuticals,
Inc. ("Pharmaceuticals").  Pharmaceuticals proposes to offer certain equity
securities to raise capital of up to $12 million (the "Offering").  

5.

The parties desire to enter into certain transactions to facilitate the
repayment of the Notes and the Incentive Debentures.

In view of the foregoing facts, the parties agree as follows:

1.

The parties agree that the outstanding principal balance of each Note as of June
30, 2007, is set forth in the following table:

Date Issued

Principal at 6/30/07

6/30/2005

0

8/1/2005

840,000

10/21/2005

0

12/15/2005

867,045

3/13/2006

549,881

4/18/2006

1,414,872

5/19/2006

1,300,000

6/30/2006

0

2.

Beginning on the date of this letter agreement, the payment amount described in
this paragraph 2 shall be in addition to the payment amount currently provided
under the Notes.  Within 45 days after the end of each calendar quarter,
DNAPrint Genomics, Inc. shall pay to Dutchess a payment on the Notes equal to
the sum of (i) 80% of the royalty income paid to DNAPrint Genomics, Inc. by
Pharmaceuticals during the preceding calendar quarter, and (ii) 4% of all other
cash received by DNAPrint Genomics, Inc. from sales of goods or services during
the preceding calendar quarter.  

--------------------------------------------------------------------------------

3.

On the date on which the Pharmaceuticals common stock either (i) becomes subject
to the reporting requirements of Section 12 of the Securities Exchange Act of
1934, or (ii) becomes listed or eligible for trading on any exchange or other
trading system (the “Pharmaceuticals Issuance Date"), DNAPrint Genomics, Inc.
shall cause Pharmaceuticals to issue to Dutchess warrants to purchase 2 million
shares of Pharmaceuticals common stock, at an exercise price of $0.01 per share,
expiring July 31, 2012.  Such warrants shall be issued in full payment of the
Incentive Debentures, and immediately upon the issuance of such warrants, any
and all Incentive Debentures shall be discharged in full, and Dutchess shall
surrender to DNAPrint the original executed Incentive Debentures.  If the
balance on the Incentives Debentures as of the Pharmaceuticals Issuance Date is
less than $2 million (such difference being referred to as the "Shortfall"),
then on such date, DNAPrint shall be deemed to have made a principal payment on
the Notes in the amount of the Shortfall.

4.

On the Pharmaceuticals Issuance Date, DNAPrint shall cause Pharmaceuticals to
issue to Dutchess up to 2 million shares of Pharmaceuticals common stock as a
payment of amounts due under the Notes; provided, however, in no event shall
DNAPrint be required to issue to Dutchess shares having a value in excess of the
amounts then due under the Notes.  For purposes of determining the amount of
such payment, the Pharmaceuticals common stock shall have a deemed value equal
to the gross sales proceeds realized by Dutchess upon its disposition of such
stock.

5.

Dutchess hereby consents to the formation of Pharmaceuticals and the transfer of
assets to Pharmaceuticals and hereby releases its security interest in such
assets and in the common stock of Pharmaceuticals.  

6.

Except as explicitly set forth in this letter agreement, the Investment
Agreement and the Notes shall remain in effect to the same extent that they were
in effect prior to the date hereof.

 

 

Very truly yours,

 

 

         

 

 

           

 

 

Dutchess Private Equities Fund, Ltd.

 

 

         

 

By:

Dutchess Private Equities Fund, Ltd.

 

 

         

 

 

         

 

By:

/s/ Douglas H. Leighton

 

 

Douglas H. Leighton

 

 

Director

 

 

Accepted and agreed to:

 

 

         

 

 

DNAPrint Genomics, Inc.

 

 

           

 

 

                  

 

By:

/s/ Richard Gabriel

 

 

Richard Gabriel

 

 

President