THE SECURITIES  REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED ("1933 ACT"), OR ANY STATE SECURITIES LAWS AND SHALL NOT
BE SOLD, PLEDGED,  HYPOTHECATED,  DONATED, OR OTHERWISE TRANSFERRED,  WHETHER OR
NOT FOR CONSIDERATION,  BY THE HOLDER EXCEPT UPON THE ISSUANCE TO THE COMPANY OF
A  FAVORABLE  OPINION OF ITS  COUNSEL OR THE  SUBMISSION  TO THE COMPANY OF SUCH
OTHER  EVIDENCE AS MAY BE  SATISFACTORY  TO COUNSEL FOR THE  COMPANY,  IN EITHER
CASE, TO THE EFFECT THAT ANY SUCH TRANSFER SHALL NOT BE IN VIOLATION OF THE 1933
ACT AND APPLICABLE STATE SECURITIES LAWS.


                         CALYPTE BIOMEDICAL CORPORATION

                          Common Stock Purchase Warrant
                                       to
                             Purchase 500,000 Shares
                                       of
                          Common Stock, $0.03 par value

                This Common Stock Purchase Warrant is issued to:

                              Marr Technologies BV
                               Strawinskylaan 1439
                                 1077 Amsterdam
                                 The Netherlands

by CALYPTE BIOMEDICAL  CORPORATION,  a Delaware corporation  (hereinafter called
the "Company", which term shall include its successors and assigns).

      FOR VALUE RECEIVED and subject to the terms and conditions hereinafter set
out, the registered holder of this Warrant as set forth on the books and records
of the Company  (the  "Holder")  is entitled  upon  surrender of this Warrant to
purchase from the Company 500,000 fully paid and non-assessable shares of Common
Stock, $0.03 par value per share (the "Common Stock"), at the Exercise Price (as
defined below) per share.

      This Warrant shall expire at the close of business on May 26, 2006.

      1. (a) The right to purchase  shares of Common Stock  represented  by this
Warrant may be exercised by the Holder, in whole or in part, by the surrender of
this Warrant  (properly  endorsed if required)  at the  principal  office of the
Company at 1265 Harbor Parkway, Alameda,  California 94502 (or such other office
or agency of the Company as it may  designate by notice in writing to the Holder
at the address of the Holder  appearing on the books of the  Company),  and upon
payment to the  Company,  by cash or by  certified  check or bank draft,  of the
Exercise  Price for such  shares.  The Company  agrees that the shares of Common
Stock so  purchased  shall be deemed to be  issued to the  Holder as the  record


<PAGE>


owner of such shares of Common  Stock as of the close of business on the date on
which this Warrant shall have been  surrendered and payment made for such shares
of Common  Stock as  aforesaid.  Certificates  for the shares of Common Stock so
purchased  (together with a cash  adjustment in lieu of any fraction of a share)
shall be delivered to the Holder within a reasonable  time,  not exceeding  five
(5) business days, after the rights  represented by this Warrant shall have been
so exercised,  and, unless this Warrant has expired, a new Warrant  representing
the number of shares of Common Stock, if any, with respect to which this Warrant
shall not then have been  exercised,  in all other respects  identical with this
Warrant,  shall also be issued and delivered to the Holder within such time, or,
at the request of the Holder,  appropriate  notation may be made on this Warrant
and the same returned to the Holder.

            (b) This  Warrant may be  exercised  to acquire,  from and after the
date  hereof,  the number of shares of Common  Stock set forth on the first page
hereof (subject to adjustments  described in this Warrant);  provided,  however,
the right hereunder to purchase such shares of Common Stock shall expire at 5:00
p.m. Alameda, California time on May 26, 2006.

      2. This  Warrant is being  issued by the Company  pursuant to the terms of
Amendment No 2, dated May 26, 2004, to the Agreement for  Commitment to Purchase
Aggregate of $10,000,000  of 5% Promissory  Notes dated as of November 13, 2003.

      3. The Company  covenants  and agrees that all Common Stock upon  issuance
against  payment in full of the  Exercise  Price by the Holder  pursuant to this
Warrant will be validly issued,  fully paid and non-assessable and free from all
taxes, liens and charges with respect to the issue thereof (except to the extent
resulting  from the  Holder's  own  circumstances,  actions or  omissions).  The
Company  covenants  and agrees  that during the period  within  which the rights
represented by this Warrant may be exercised, the Company will have at all times
authorized,  and reserved for the purpose of issue or transfer  upon exercise of
the rights  evidenced by this Warrant,  a sufficient  number of shares of Common
Stock to provide for the exercise of the rights represented by this Warrant, and
will  procure  at its sole  expense  upon each such  reservation  of shares  the
listing  thereof  (subject  to  issuance  or  notice of  issuance)  on all stock
exchanges  on which the  Common  Stock is then  listed or  inter-dealer  trading
systems on which the Common Stock is then traded. The Company will take all such
action as may be  necessary to assure that such shares of Common Stock may be so
issued  without  violation  of  any  applicable  law  or  regulation,  or of any
requirements of any national securities exchange upon which the Common Stock may
be listed or  inter-dealer  trading  system  on which the  Common  Stock is then
traded.  The  Company  will  not take  any  action  which  would  result  in any
adjustment in the number of shares of Common Stock purchasable  hereunder if the
total  number of shares of Common Stock  issuable  pursuant to the terms of this
Warrant after such action upon full exercise of this Warrant and,  together with
all shares of Common Stock then  outstanding and all shares of Common Stock then
issuable  upon  exercise of all options and other  rights to purchase  shares of
Common Stock then outstanding, would exceed the total number of shares of Common
Stock  then  authorized  by the  Company's  Restated  and  Amended  Articles  of
Incorporation, as then amended.


<PAGE>


      4. The Initial Exercise Price is $0.40 per share of Common Stock ("Initial
Exercise  Price").  The Initial Exercise Price shall be adjusted as provided for
below in this Section 4 (the Initial  Exercise Price,  and the Initial  Exercise
Price,  as  thereafter  then  adjusted,  shall be referred  to as the  "Exercise
Price") and the  Exercise  Price from time to time shall be further  adjusted as
provided  for below in this  Section  4. Upon each  adjustment  of the  Exercise
Price,  the Holder shall thereafter be entitled to receive upon exercise of this
Warrant,  at the Exercise Price  resulting from such  adjustment,  the number of
shares of Common Stock obtained by (i)  multiplying the Exercise Price in effect
immediately  prior to such  adjustment  by the number of shares of Common  Stock
purchasable  hereunder  immediately prior to such adjustment,  and (ii) dividing
the product  thereof by the Exercise Price resulting from such  adjustment.  The
Exercise Price shall be adjusted as follows:

                  (i) In the case of any amendment to the Company's  Articles of
         Incorporation  to change the  designation  of the  Common  Stock or the
         rights, privileges, restrictions or conditions in respect to the Common
         Stock or division of the Common  Stock,  this Warrant shall be adjusted
         so as to provide that upon exercise thereof,  the Holder shall receive,
         in lieu of each share of Common Stock  theretofore  issuable  upon such
         exercise,  the kind and amount of shares,  other securities,  money and
         property  receivable upon such  designation,  change or division by the
         Holder   issuable  upon  such   exercise  had  the  exercise   occurred
         immediately prior to such designation, change or division. This Warrant
         shall be deemed  thereafter to provide for adjustments,  which shall be
         as nearly equivalent as may be practicable to the adjustments  provided
         for in this Section 4. The  provisions  of this  Subsection  4(i) shall
         apply in the same  manner  to  successive  reclassifications,  changes,
         consolidations  and  mergers.  (ii) If the  Company  shall  at any time
         subdivide its outstanding  shares of Common Stock into a greater number
         of shares of Common  Stock,  or  declare a  dividend  or make any other
         distribution  upon the Common Stock  payable in shares of Common Stock,
         the Exercise Price in effect  immediately  prior to such subdivision or
         dividend or other distribution shall be  proportionately  reduced,  and
         conversely,  in case the  outstanding  shares of Common  Stock shall be
         combined into a smaller number of shares of Common Stock,  the Exercise
         Price  in  effect  immediately  prior  to  such  combination  shall  be
         proportionately increased.

                  (iii) If any capital reorganization or reclassification of the
         capital  stock of the Company,  or any  consolidation  or merger of the
         Company with or into another  corporation or other entity,  or the sale
         of  all  or  substantially  all  of the  Company's  assets  to  another
         corporation  or  other  entity  shall  be  effected  in such a way that
         holders of shares of Common  Stock shall be entitled to receive  stock,
         securities,  other evidence of equity  ownership or assets with respect
         to or in exchange for shares of Common  Stock,  then, as a condition of
         such reorganization,  reclassification,  consolidation,  merger or sale
         (except as  otherwise  provided  below in this  Section 4),  lawful and
         adequate  provisions  shall be made whereby the Holder shall thereafter
         have the right to receive upon the  exercise  hereof upon the basis and
         upon the terms and conditions  specified herein,  such shares of stock,


<PAGE>


         securities,  other  evidence  of equity  ownership  or assets as may be
         issued  or  payable  with  respect  to or in  exchange  for a number of
         outstanding  shares of such Common  Stock equal to the number of shares
         of Common Stock immediately theretofore purchasable and receivable upon
         the   exercise  of  this   Warrant   under  this  Section  4  had  such
         reorganization,  reclassification,  consolidation,  merger  or sale not
         taken place, and in any such case appropriate  provisions shall be made
         with respect to the rights and  interests of the Holder to the end that
         the provisions hereof (including,  without  limitation,  provisions for
         adjustments of the Exercise Price and of the number of shares of Common
         Stock receivable upon the exercise of this Warrant) shall thereafter be
         applicable,  as nearly as may be, in  relation  to any shares of stock,
         securities,  other  evidence of equity  ownership or assets  thereafter
         deliverable   upon  the  exercise   hereof   (including   an  immediate
         adjustment,  by reason of such consolidation or merger, of the Exercise
         Price to the value for the Common Stock  reflected by the terms of such
         consolidation  or  merger if the  value so  reflected  is less than the
         Exercise Price in effect  immediately  prior to such  consolidation  or
         merger). Subject to the terms of this Warrant, in the event of a merger
         or  consolidation  of the Company with or into another  corporation  or
         other  entity as a result of which the number of shares of common stock
         of the  surviving  corporation  or other entity  issuable to holders of
         Common Stock,  is greater or lesser than the number of shares of Common
         Stock  outstanding  immediately  prior to such merger or consolidation,
         then the Exercise Price in effect  immediately  prior to such merger or
         consolidation shall be adjusted in the same manner as though there were
         a subdivision or combination of the outstanding shares of Common Stock.
         The Company  shall not effect any such  consolidation,  merger or sale,
         unless, prior to the consummation  thereof,  the successor  corporation
         (if other than the Company) resulting from such consolidation or merger
         or the  corporation  purchasing  such  assets  shall  assume by written
         instrument  executed  and  mailed  or  delivered  to  the  Holder,  the
         obligation  to deliver to the Holder such shares of stock,  securities,
         other evidence of equity ownership or assets as, in accordance with the
         foregoing  provisions,  the  Holder  may  be  entitled  to  receive  or
         otherwise acquire.  If a purchase,  tender or exchange offer is made to
         and  accepted by the  holders of more than fifty  (50%)  percent of the
         outstanding  shares of Common  Stock,  the Company shall not effect any
         consolidation, merger or sale with the person having made such offer or
         with any affiliate of such person,  unless prior to the consummation of
         such  consolidation,  merger or sale the Holder of this  Warrant  shall
         have been given a reasonable  opportunity to then elect to receive upon
         the  exercise of this  Warrant the amount of stock,  securities,  other
         evidence of equity  ownership or assets then  issuable  with respect to
         the number of shares of Common Stock in accordance with such offer.

                  (iv) In case the Company shall,  at any time prior to exercise
         of this Warrant,  consolidate  or merge with any other  corporation  or
         other  entity  (where  the  Company  is not the  surviving  entity)  or
         transfer  all  or  substantially   all  of  its  assets  to  any  other
         corporation  or other entity,  then the Company  shall,  as a condition
         precedent to such transaction,  cause effective provision to be made so
         that the Holder of this Warrant upon the exercise of this Warrant after
         the effective date of such transaction shall be entitled to receive the


<PAGE>


         kind and amount of  shares,  evidences  of  indebtedness  and/or  other
         securities or property  receivable on such  transaction  by a holder of
         the  number  of shares of Common  Stock as to which  this  Warrant  was
         exercisable  immediately  prior  to such  transaction  (without  giving
         effect to any restriction  upon such exercise);  and, in any such case,
         appropriate  provision  shall be made with  respect  to the  rights and
         interest of the Holder of this  Warrant to the end that the  provisions
         of this Warrant shall  thereafter  be  applicable  (as nearly as may be
         practicable)  with respect to any shares,  evidences of indebtedness or
         other securities or assets thereafter deliverable upon exercise of this
         Warrant.  Upon the  occurrence  of any event  described in this Section
         4(iv),  the holder of this Warrant shall have the right to (i) exercise
         this Warrant immediately prior to such event at an Exercise Price equal
         to lesser of (1) the then Exercise  Price or (2) the price per share of
         Common  Stock paid in such  event,  or (ii)  retain  ownership  of this
         Warrant, in which event,  appropriate  provisions shall be made so that
         the Warrant shall be exercisable at the Holder's  option into shares of
         stock,  securities  or  other  equity  ownership  of the  surviving  or
         acquiring entity.

         Whenever the Exercise Price shall be adjusted  pursuant to this Section
4, the  Company  shall  issue a  certificate  signed  by its  President  or Vice
President  and by its  Treasurer,  Assistant  Treasurer,  Secretary or Assistant
Secretary,  setting  forth,  in  reasonable  detail,  the  event  requiring  the
adjustment,  the amount of the  adjustment,  the method by which such adjustment
was  calculated  (including  a  description  of the  basis on which the Board of
Directors of the Company  made any  determination  hereunder),  and the Exercise
Price after  giving  effect to such  adjustment,  and shall cause copies of such
certificates to be mailed (by first-class  mail,  postage prepaid) to the Holder
of this  Warrant.  The Company  shall make such  certificate  and mail it to the
Holder promptly after each adjustment.

         No fractional shares of Common Stock shall be issued in connection with
any exercise of this Warrant, but in lieu of such fractional shares, the Company
shall  make a cash  payment  therefore  equal in  amount to the  product  of the
applicable  fraction  multiplied by the Exercise Price then in effect.

         5. In the event the Company  grants rights  (other than rights  granted
pursuant to a  shareholder  rights or poison pill plan) to all  shareholders  to
purchase Common Stock,  the Holder shall have the same rights as if this Warrant
had been exercised immediately prior to such grant.

         6. The  shares of  Common  Stock  issuable  upon the  exercise  of this
Warrant shall have piggyback  rights for inclusion in a  registration  statement
filed by the Company pursuant to a Form SB-2 to be filed with the Securities and
Exchange Commission on or prior to June 30, 2004.

         7.  This  Warrant  need not be  changed  because  of any  change in the
Exercise Price or in the number of shares of Common Stock  purchased  hereunder.


<PAGE>


      8. The terms  defined in this  paragraph,  whenever  used in this Warrant,
shall,  unless the context  otherwise  requires,  have the  respective  meanings
hereinafter  specified.  The term  "Common  Stock"  shall mean and  include  the
Company's Common Stock, $0.03 par value per share, authorized on the date of the
original  issue  of  this  Warrant  and  shall  also  include  in  case  of  any
reorganization, reclassification, consolidation, merger or sale of assets of the
character  referred  to in  Section 4 hereof,  the stock,  securities  or assets
provided  for in such  paragraph.  The term  "Company"  shall also  include  any
successor corporation to Calypte Biomedical Corporation by merger, consolidation
or otherwise.  The term  "outstanding"  when used with reference to Common Stock
shall  mean at any  date as of which  the  number  of  shares  thereof  is to be
determined,  all issued shares of Common Stock, except shares then owned or held
by or for the  account  of the  Company.  The term  "1933  Act"  shall  mean the
Securities Act of 1933, as amended,  or any successor  Federal statute,  and the
rules and  regulations of the Securities and Exchange  Commission,  or any other
Federal agency then  administering  the 1933 Act,  there-under,  all as the same
shall be in effect at the time.

      9. This Warrant is  exchangeable,  upon the surrender hereby by the Holder
at the  office  or  agency  of the  Company,  for new  Warrants  of  like  tenor
representing in the aggregate the right to subscribe for and purchase the number
of shares of Common Stock which may be subscribed  for and purchased  hereunder,
each of such new Warrants to represent  the right to subscribe  for and purchase
such number of shares of Common  Stock as shall be  designated  by the Holder at
the time of such surrender. Upon receipt of evidence satisfactory to the Company
of the loss,  theft,  destruction  or mutilation of this Warrant or any such new
Warrants and, in the case of any such loss, theft, or destruction, upon delivery
of a bond of indemnity,  reasonably satisfactory to the Company, or, in the case
of any such  mutilation,  upon surrender or cancellation of this Warrant or such
new Warrants,  the Company will issue to the Holder a new Warrant of like tenor,
in lieu  of this  Warrant  or such  new  Warrants,  representing  the  right  to
subscribe  for and  purchase  the number of shares of Common  Stock which may be
subscribed for and purchased hereunder.

      10. The  Company  will at no time close its  transfer  books  against  the
transfer  of this  Warrant or of any shares of Common  Stock  issued or issuable
upon the exercise of this warrant in any manner which interferes with the timely
exercise  of this  Warrant.  This  Warrant  shall not  entitle the Holder to any
voting  rights or any rights as a  shareholder  of the  Company.  The rights and
obligations of the Company, of the Holder, and of any holder of shares of Common
Stock issuable hereunder, shall survive the exercise of this Warrant.

      11. This  Warrant  sets forth the entire  agreement of the Company and the
Holder of the Common  Stock  issuable  upon the  exercise of this  Warrant  with
respect  to the rights of the Holder  and the  Common  Stock  issuable  upon the
exercise of this  Warrant,  notwithstanding  the knowledge of such Holder of any
other agreement or the provisions of any agreement,  whether or not known to the
Holder,  and the Company  represents  that there are no agreements  inconsistent
with the terms  hereof or which  purport  in any way to bind the  Holder of this
Warrant  or the Common  Stock.  12.  The laws of the State of  California  shall
govern the validity,  interpretation and performance of this Warrant and each of
its terms and provisions.

      IN WITNESS  WHEREOF,  the Company has caused this  Warrant to be signed by
its duly  authorized  officer under its  corporate  seal and dated as of May 26,
2004.

CALYPTE BIOMEDICAL CORPORATION

By /s/ Richard D. Brounstein
  ---------------------------------
  Name: Richard D. Brounstein
  Title: Executive Vice President & CFO


<PAGE>


                          FORM OF ELECTION TO PURCHASE

(To be executed by the Holder to exercise the right to purchase shares of Common
Stock under the Warrant to which this form applies, issued by Calypte Biomedical
Corporation ("Calypte"))

To Calypte Biomedical Corporation:

      The undersigned hereby irrevocably elects to purchase _____________ shares
of common stock, $0.03 par value per share, of Calypte (the "Common Stock") and,
encloses herewith $________ in cash, certified or official bank check or checks,
which sum represents the aggregate Exercise Price (as defined in the Warrant)
for the number of shares of Common Stock to which this Form of Election to
Purchase relates, together with any applicable taxes payable by the undersigned
pursuant to the Warrant.

      The undersigned requests that certificates for the shares of Common Stock
issuable upon this exercise be issued in the name of


                                    PLEASE INSERT SOCIAL SECURITY OR
                                    TAX IDENTIFICATION NUMBER


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



--------------------------------------------------------------------------------
                        (Please print name and address)




Dated:            ,                    Name of Holder:
      ------------ ------

                                         (Print)
                                                -------------------------------
                                         (By:)
                                              ---------------------------------
                                         (Name:)
                                         (Title:)
                                         (Signature must conform in all respects
                                         to  name of holder  as specified on the
                                         face of the Warrant)


<PAGE>


                                 FORM OF ASSIGNMENT


[To be completed and signed only upon transfer of Warrant]

      FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers
unto ________________________________ the right represented by the within
Warrant to purchase ____________ shares of Common Stock of Calypte Biomedical
Corporation to which the within Warrant relates and appoints ________________
attorney to transfer said right on the books of Calypte Biomedical Corporation
with full power of substitution in the premises.

Dated:

_______________, ____


                                     ___________________________________________
                                     (Signature  must  conform in all  respects
                                     to name of holder as specified on the face
                                     of the Warrant)


                                     ___________________________________________
                                     Address of Transferee

                                     ___________________________________________

                                     ___________________________________________




In the presence of:


__________________________