**AMENDMENT
      TO SECURED 8% CONVERTIBLE PROMISSORY NOTES**









THIS
      AMENDMENT (this " **Amendment** ")
      to
      Secured 8% Convertible Promissory Notes (the " **Notes** ")
      is
      made as of March 21, 2007, by and between Calypte Biomedical Corporation, a
      Delaware corporation (the " **Company** "),
      and
      SF Capital Partners Ltd. (the “ **Investor** ”).
      If
      there is any inconsistency between the terms of this Amendment and any other
      agreement referenced herein, the terms of this Amendment will
      govern.




WHEREAS,
      the Company and the Investor are parties to (i) the Securities Purchase
      Agreement dated May 28, 2004 (the “ **Securities
      Purchase Agreement** ”)
      among
      the Company and the investors signatory thereto ( “ **Investors
      I** ”),
      pursuant to which the Company issued and sold to Investors I, and Investors
      I
      purchased from the Company, certain shares and warrants pursuant to the terms
      set forth in the Securities Purchase Agreement, (ii) the Amendment to Securities
      Purchase Agreement dated April 4, 2005 (the “ **Amendment
      to Securities Purchase Agreement** ”)
      among
      the Company and Investors I, pursuant to which Investors I received certain
      anti-dilution entitlements and new entitlements, including, without limitation,
      certain warrants (the “ **2004**  **Amendment
      Warrants** ”)
      pursuant to the terms set forth in the Amendment to Securities Purchase
      Agreement, (iii) the Purchase Agreement dated as of April 4, 2005 (the **"Purchase
      Agreement"** )
      among
      the Company and the investors signatory thereto ( “ **Investors
      II** ”),
      pursuant to which the Company issued and sold to Investors II, and Investors
      II
      purchased from the Company, certain secured 8% convertible promissory notes,
      which included the Notes, Series A warrants (the “ **2005
      Series A Warrants** ”)
      and
      Series B warrants (the “ **2005
      Series B Warrants** ”)
      pursuant to the terms set forth in the Purchase Agreement, and (iv) the letter
      agreement dated July 7, 2006 (the “ **Letter
      Agreement** ”)
      between the Company and the Investor, pursuant to which the 2004 Warrants and
      the 2004 Amendment Warrants were amended to lower their exercise price from
      $0.45 to $0.15 for a period of time commencing through and including July 21,
      2006, after which time the exercise price reverted back to $0.45 (the
“ **2005**  **Amendment
      Warrants** ”)
      and to
      issue to the Investor an additional warrant equal to 50% of the aggregate amount
      of the 2005 Amendment Warrants exercised before July 21, 2006 (the “ **2006**  **Additional
      Warrant** ”);




WHEREAS,
      the parties now desire to change the maturity date (the “ **Maturity
      Date** ”)
      of the
      Notes issued by the Company to the Investor pursuant to the Purchase Agreement
      in the initial principal amount of $4,000,000 in accordance with the provisions
      set forth in Section 15(f) of the Notes and Section 6.4 of the Purchase
      Agreement;




WHEREAS,
      in consideration of the foregoing, the Company agrees to lower the exercise
      price of the Investor’s currently outstanding warrants, which consist of 2005
      Series A Warrants, 2005 Series B Warrants, and 2006 Additional Warrant
      (collectively, the “ **Warrants** ”),
      which
      equal an aggregate of 21,491,666 shares of the Company’s common stock (the
“ **Warrant
      Shares** ”),
      as
      follows: the Exercise Price of 40% of the Warrants Shares, equaling 8,596,666
      Warrant Shares from the 2005 Series A Warrant will be lowered to $0.03 per
      Warrant Share and the Exercise Price of 60% of the Warrant Shares, equaling
      12,775,000 Warrant Shares, from the Series A Warrant, Series B Warrant, 2005
      Amendment Warrant and 2006 Additional Warrant, will be lowered to $0.10 per
      Warrant Share, all as more particularly set forth on Schedule
      1 attached
      hereto, and to change the expiration date of the 2006 Additional Warrant to
      coincide with the change of the Maturity Date of the Notes; and







WHEREAS,
      the parties agree to amend and modify the 2006 Additional Warrant to delete
      the
      provision of piggyback registration rights from the 2006 Additional Warrant.




NOW,
      THEREFORE, for good and valuable consideration, the receipt and sufficiency
      of
      which are hereby acknowledged, the Company and the Investor agree as
      follows:




1.  All
      references in the Notes to the due date of “April 3, 2007” are hereby amended to
“April 3, 2009.”




2.  The
      Expiration Date (as defined in the 2006 Additional Warrant) is hereby amended
      to
      April 3, 2009.




3.  The
      Warrants are hereby amended to lower the exercise prices as more specifically
      set forth in Schedule
      1 and in
      the amended warrants, which are attached hereto as Exhibit
      A , Exhibit
      B-1 , Exhibit
      B-2 , Exhibit
      C ,
      and Exhibit
      D and to
      delete the provision of piggyback registration rights from the 2006 Additional
      Warrant.




4.  Except
      for the amendments provided for herein, the Notes and the Warrants shall remain
      unchanged and in full force and effect.




5.  This
      Amendment may be executed in counterparts, each of which shall be deemed to
      be
      an original, but which together shall be deemed to be one and the same
      instrument.




6.  This
      Amendment shall be governed by and construed in accordance with the laws of
      the
      State of New York without giving effect to the conflicts of law principles
      thereof.




[ **Signature
      Pages Follow** ]







[SIGNATURE
      PAGE FOR THE COMPANY]




**IN
      WITNESS WHEREOF** ,
      each of
      the parties hereto has caused a counterpart of this Amendment to be duly
      executed and delivered as of the date first above written.






CALYPTE
                BIOMEDICAL CORPORATIONBy:Richard
                D. Brounstein
              Executive
                Vice PresidentTitle














[SIGNATURE
      PAGE FOR THE INVESTOR]




**IN
      WITNESS WHEREOF** ,
      the
      parties hereto has caused a counterpart of this Amendment to be duly executed
      and delivered as of the date first above written.




SF
                Capital Partners Ltd.Name
                of InvestorBy:SignatureIts:Title


















**Calypte
                  Biomedical Corporation****SF
                  CAPITAL WARRANTS****SCHEDULE
                  1**2007
                  Warrant Repricing
  SF
                  Capital Partners
              
              Warrant
              
              Issue
              
              Expiration
              
              
              
              Current
                  Warrants
              
              March
                  2007 RepricingHolder
              
              No.
              
              Date
              
              Date
              
              Source
              
              Shares
              
              
              Price
              
              Shares
              
              
              PriceExhibit
                  A
              
              05-016
              
              30-Jun-05
              
              28-May-09
              
              2004
                  PIPE Anti-Dilution new warrants
              
              408,333
              
              $
              0.325
              
              408,333
              
              $
              0.10Exhibit
                  B-1
              
              05-001
              
              04-Apr-05
              
              03-Apr-10
              
              April
                  '05 Notes - Series A Warrants
              
              13,333,333
              
              $
              0.325
              
              8,596,666
              
              $
              0.03Exhibit
                  B-2
              
              
              
              
              
              
              
              
              
              
              
              $
              0.325
              
              4,736,667
              
              $
              0.10Exhibit
                  C
              
              05-006
              
              04-Apr-05
              
              03-Apr-10
              
              April
                  '05 Notes - Series B Warrants
              
              6,000,000
              
              $
              0.325
              
              6,000,000
              
              $
              0.10Exhibit
                  D
              
              06-002
              
              03-Aug-06
              
              03-Apr-09
              
              2006
                  Additional Warrants
              
              1,750,000
              
              $
              0.25
              
              1,750,000
              
              $
              0.1021,491,666
              
              
              
              
              21,491,666