**REGISTRATION
      RIGHTS AGREEMENT**




This
      Registration Rights Agreement (this **“Agreement”** )
      is made
      and entered into as of March 28, 2007, by and among Calypte Biomedical
      Corporation, a Delaware corporation (the **“Company”** ),
      and
      the investors signatory hereto (each a **“Investor”** and
      collectively, the **“Investors”** ).




This
      Agreement is made pursuant to the Subscription Agreement, dated on or before
      March 28, 2007, among the Company and the Investors (the **“Purchase
      Agreement”** ).




The
      Company and the Investors hereby agree as follows:




1.  Definitions .
      Capitalized terms used and not otherwise defined herein that are defined in
      the
      Subscription Agreement shall have the meanings given such terms in the
      Subscription Agreement. As used in this Agreement, the following terms shall
      have the respective meanings set forth in this Section 1:




**“Effective
      Date”** means
      the date that the Registration Statement filed pursuant to Section 2(a) is
      first
      declared effective by the Commission.





**“Effectiveness
      Date”** means
      (a) with respect to the Registration Statement required to be filed under
      Section 2(a), the fifth Trading Day following the date on which the Company
      is
      notified by the Commission that the First Registration Statement will not be
      reviewed or is no longer subject to further review and comments and (b) with
      respect to any additional Registration Statements that may be required pursuant
      to Section 2(b), (x) if such Registration Statement is required because the
      Commission shall have notified the Company in writing that certain Registrable
      Securities were not eligible for inclusion on a previously filed Registration
      Statement, the date or time on which the Commission shall indicate as being
      the
      first date or time that such Registrable Securities may then be included in
      a
      Registration Statement, or (y) if such Registration Statement is required for
      a
      reason other than as described in (x) above, the date on which the Company
      first
      knows, or reasonably should have known, that such additional Registration
      Statement(s) is required, and (ii) the fifth Trading Day following the date
      on
      which the Company is notified by the Commission that such additional
      Registration Statement will not be reviewed or is no longer subject to further
      review and comment.




**“Effectiveness
      Period”** shall
      have the meaning set forth in Section 2(a).




**“Exchange
      Act”** means
      the Securities Exchange Act of 1934, as amended.




**“Filing
      Date”** means
      (a) with respect to the initial Registration Statement required to be filed
      under Section 2(a), the 45 th day
      following the March 28, 2007 Closing Date and (b) with respect to any additional
      Registration Statements that may be required pursuant to Section 2(b), the
      45 th day
      following (x) if such Registration Statement is required because the Commission
      shall have notified the Company in writing that certain Registrable Securities
      were not eligible for inclusion on a previously filed Registration Statement,
      the date or time on which the Commission shall indicate as being the first
      date
      or time that such Registrable Securities may then be included in a Registration
      Statement, or (y) if such Registration Statement is required for a reason other
      than as described in (x) above, the date on which the Company first knows,
      or
      reasonably should have known, that such additional Registration Statement(s)
      is
      required.




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**“Investor”** or **“Investors”** means
      the Investor or Investors, as the case may be, from time to time of Registrable
      Securities.




**“Indemnified
      Party”** shall
      have the meaning set forth in Section 5(c).




**“Indemnifying
      Party”** shall
      have the meaning set forth in Section 5(c).




**“Losses”** shall
      have the meaning set forth in Section 5(a).




**“Notes”** means,
      collectively, each of the promissory notes issued or issuable under the Purchase
      Agreement.




**“Proceeding”** means an
      action, claim, suit, investigation or proceeding (including, without limitation,
      an investigation or partial proceeding, such as a deposition), whether commenced
      or threatened.





**“Prospectus”** means
      the prospectus included in a Registration Statement (including, without
      limitation, a prospectus that includes any information previously omitted from
      a
      prospectus filed as part of an effective registration statement in reliance
      upon
      Rule 430A promulgated under the Securities Act), as amended or supplemented
      by
      any prospectus supplement, with respect to the terms of the offering of any
      portion of the Registrable Securities covered by a Registration Statement,
      and
      all other amendments and supplements to the Prospectus, including post-effective
      amendments, and all material incorporated by reference or deemed to be
      incorporated by reference in such Prospectus.





**“Registrable
      Securities”** means
      the (a) Underlying Shares issuable upon conversion of the Notes (assuming such
      Notes are held until the maturity date thereof and all interest is accreted
      to
      principal thereunder together with any securities issued or issuable upon any
      stock split, dividend or other distribution, recapitalization or similar event,
      or any conversion price adjustment with respect thereto), and (b) Warrant Shares
      issuable upon exercise of the Warrants.




**“Registration
      Statement”** means
      the initial registration statement required to be filed in accordance with
      Section 2(a) and any additional registration statement, if any, contemplated
      by
      Section 2(b), and including, in each case, the Prospectus, amendments and
      supplements to each such registration statement or Prospectus, including pre-
      and post-effective amendments, all exhibits thereto, and all material
      incorporated by reference or deemed to be incorporated by reference in such
      registration statement.




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**“Rule
      144”** means
      Rule 144 promulgated by the Commission pursuant to the Securities Act, as such
      Rule may be amended from time to time, or any similar rule or regulation
      hereafter adopted by the Commission having substantially the same effect as
      such
      Rule.




**“Rule
      415”** means
      Rule 415 promulgated by the Commission pursuant to the Securities Act, as such
      Rule may be amended from time to time, or any similar rule or regulation
      hereafter adopted by the Commission having substantially the same effect as
      such
      Rule.




**“Rule
      424”** means
      Rule 424 promulgated by the Commission pursuant to the Securities Act, as such
      Rule may be amended from time to time, or any similar rule or regulation
      hereafter adopted by the Commission having substantially the same effect as
      such
      Rule.




**“Securities
      Act”** means
      the Securities Act of 1933, as amended.




2.  Registration .




(a)  On
      or
      prior to each Filing Date, the Company shall prepare and file with the
      Commission a Registration Statement covering the resale of all Registrable
      Securities not already covered by an existing and effective Registration
      Statement for an offering to be made on a continuous basis pursuant to Rule
      415.
      The Registration Statement shall be on Form SB-2 or Form S-3 (except if the
      Company is not then eligible to register for resale the Registrable Securities
      on Form SB-2 or Form S-3, in which case such registration shall be on
      another appropriate form for such purpose) and shall contain (except if
      otherwise required pursuant to written comments received from the Commission
      upon a review of such Registration Statement) the “Plan of Distribution”
attached hereto as Annex
      A .
      The
      Company shall use its best efforts to cause each Registration Statement to
      be
      declared effective under the Securities Act within 120 days following the
      Closing Date and shall use its best efforts to keep each Registration Statement
      continuously effective under the Securities Act until the second year after
      the
      date that the Registration Statement is declared effective by the Commission
      or
      such earlier date when all Registrable Securities covered by the Registration
      Statement 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 Investors (the **“Effectiveness
      Period”** ).
      The
      initial Registration Statement shall include a number of Registrable Securities
      equal to the sum of (a) 100,000,000, the
      number of Shares issued at the Closing, and (b) 150,000,000, the
      number of shares issuable upon exercise in full of the Warrants.




(b)  If
      for
      any reason the Commission does not permit all of the Registrable Securities
      to
      be included in the Registration Statement filed pursuant to Section 2(a) or
      for
      any other reason all such Registrable Securities are not then included in an
      effective Registration Statement, then the Company shall prepare and file as
      soon as possible after the date on which the Commission shall indicate as being
      the first date or time that such filing may be made, but in any event by the
      Filing Date therefor, an additional Registration Statement covering the resale
      of all Registrable Securities not already covered by an existing and effective
      Registration Statement for an offering to be made on a continuous basis pursuant
      to Rule 415, on Form SB-2 or Form S-3 (except if the Company is not then
      eligible to register for resale the Registrable Securities on Form SB-2 or
      Form S-3, in which case such registration shall be on another appropriate form
      for such purpose). Each such Registration Statement shall contain (except if
      otherwise required pursuant to written comments received from the Commission
      upon a review of such Registration Statement) the “Plan of Distribution”
attached hereto as Annex
      A .
      The
      Company shall cause each such Registration Statement to be declared effective
      under the Securities Act as soon as possible but, in any event, no later than
      its Effective Date, and shall use its best efforts to keep such Registration
      Statement continuously effective under the Securities Act during the entire
      Effectiveness Period.




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(c)  If
      a
      Registration Statement is not filed on or prior to its Filing Date (such failure
      being referred to as an **“Event,”** and the
      date on which such Event occurs being referred to as **“Event
      Date”** ),
      then
      in addition to any other rights the Investors may have under applicable law
      or
      at equity: (x) on the Event Date the Company shall pay to each Investor an
      amount, as partial liquidated damages and not as a penalty, equal to 1.0% of
      the
      amount of such Investor’s investment, such payment in cash; and (y) beginning
      with the one (1) month anniversary following each such Event Date, and on each
      monthly anniversary thereafter (if the applicable Event shall not have been
      cured by such date) until the applicable Event is cured, the Company shall
      pay
      to each Investor an amount, as partial liquidated damages and not as a penalty,
      equal to 2.0% of the aggregate amount of such Investor’s investment, such
      payment being in cash. The parties agree that the Company will not be liable for
      liquidated damages under this Section in respect of the Warrants. The partial
      liquidated damages pursuant to the terms hereof shall apply on a daily pro-rata
      basis for any portion of a month prior to the cure of an Event, including in
      the
      case of the first Event Date.




(d)  Each
      Investor agrees to furnish to the Company a completed Questionnaire in the
      form
      attached to this Agreement as Annex
      B (a **“Selling
      Securityholder Questionnaire”** ).
      The
      Company shall not be required to include the Registrable Securities of a
      Investor in a Registration Statement and shall not be required to pay any
      liquidated or other damages under Section 2(c) to any Investor who fails to
      furnish to the Company a fully completed Selling Securityholder Questionnaire
      at
      least two Trading Days prior to the Filing Date.




3.  Registration
      Procedures .




In
      connection with the Company's registration obligations hereunder, the Company
      shall:




(a)  (i)
      Prepare and file with the Commission such amendments, including post-effective
      amendments, to each Registration Statement and the Prospectus used in connection
      therewith as may be necessary to keep such Registration Statement continuously
      effective as to the applicable Registrable Securities for its Effectiveness
      Period and prepare and file with the Commission such additional Registration
      Statements in order to register for resale under the Securities Act all of
      the
      Registrable Securities; (ii) cause the related Prospectus to be amended or
      supplemented by any required Prospectus supplement, and as so supplemented
      or
      amended to be filed pursuant to Rule 424; (iii) respond as promptly as
      reasonably possible to any comments received from the Commission with respect
      to
      each Registration Statement or any amendment thereto; and (iv) comply in all
      material respects with the provisions of the Securities Act and the Exchange
      Act
      with respect to the Registration Statements and the disposition of all
      Registrable Securities covered by each Registration Statement.




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(b)  Notify
      the Investors as promptly as reasonably possible (and, in the case of (i)(A)
      below, not less than three Trading Days prior to such filing) and (if requested
      by any such Person) confirm such notice in writing no later than one Trading
      Day
      following the day (i)(A) when a Prospectus or any Prospectus supplement or
      post-effective amendment to a Registration Statement is proposed to be filed;
      and (B) with respect to each Registration Statement or any post-effective
      amendment, when the same has become effective; (ii) of any request by the
      Commission or any other Federal or state governmental authority for amendments
      or supplements to a Registration Statement or Prospectus or for additional
      information; (iii) of the issuance by the Commission of any stop order
      suspending the effectiveness of a Registration Statement covering any or all
      of
      the Registrable Securities or the initiation of any Proceedings for that
      purpose; (iv) of the receipt by the Company of any notification with respect
      to
      the suspension of the qualification or exemption from qualification of any
      of
      the Registrable Securities for sale in any jurisdiction, or the initiation
      or
      threatening of any Proceeding for such purpose; and (v) of the occurrence of
      any
      event or passage of time that makes the financial statements included in a
      Registration Statement ineligible for inclusion therein or any statement made
      in
      such Registration Statement or Prospectus or any document incorporated or deemed
      to be incorporated therein by reference untrue in any material respect or that
      requires any revisions to such Registration Statement, Prospectus or other
      documents so that, in the case of such Registration Statement or the Prospectus,
      as the case may be, it will not contain any untrue statement of a material
      fact
      or omit to state any material fact required to be stated therein or necessary
      to
      make the statements therein, in light of the circumstances under which they
      were
      made, not misleading.




(c)  Use
      its
      reasonable best efforts to avoid the issuance of, or, if issued, obtain the
      withdrawal of (i) any order suspending the effectiveness of a Registration
      Statement, or (ii) any suspension of the qualification (or exemption from
      qualification) of any of the Registrable Securities for sale in any
      jurisdiction, at the earliest practicable moment.




(d)  Furnish
      to each Investor, without charge, at least one conformed copy of each
      Registration Statement and each amendment thereto and all exhibits to the extent
      requested by such Person (excluding those previously furnished or incorporated
      by reference) promptly after the filing of such documents with the
      Commission.




(e)  Upon
      notification by the Commission that a Registration Statement will not be
      reviewed or is no longer subject to further review and comments, the Company
      shall request acceleration of such Registration Statement such that it becomes
      effective at 5:00 p.m. (New York City time) on the Effective Date.




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(f)  Deliver
      to each Investor, by 9:00 a.m. (New York City time) on the day following the
      Effective Date, without charge, as many copies of each Prospectus or
      Prospectuses (including each form of prospectus) and each amendment or
      supplement thereto as such Persons may reasonably request. The Company hereby
      consents to the use of such Prospectus and each amendment or supplement thereto
      by each of the selling Investors in connection with the offering and sale of
      the
      Registrable Securities covered by such Prospectus and any amendment or
      supplement thereto.




(g)  Prior
      to
      any public offering of Registrable Securities, use its best efforts to register
      or qualify or cooperate with the selling Investors in connection with the
      registration or qualification (or exemption from such registration or
      qualification) of such Registrable Securities for offer and sale under the
      securities or Blue Sky laws of all jurisdictions within the United States,
      to
      keep each such registration or qualification (or exemption therefrom) effective
      during the Effectiveness Period and to do any and all other acts or things
      necessary or advisable to enable the disposition in such jurisdictions of the
      Registrable Securities covered by the Registration Statements; provided ,
      that
      the Company shall not be required to qualify generally to do business in any
      jurisdiction where it is not then so qualified or subject the Company to any
      material tax in any such jurisdiction where it is not then so
      subject.




(h)  Cooperate
      with the Investors to facilitate the timely preparation and delivery of
      certificates representing Registrable Securities to be delivered to a transferee
      pursuant to the Registration Statements, which certificates shall be free,
      to
      the extent permitted by the Purchase Agreement, of all restrictive legends,
      and
      to enable such Registrable Securities to be in such denominations and registered
      in such names as any such Investors may request.




4.  Registration
      Expenses .
      All
      fees and expenses incident to the performance of or compliance with this
      Agreement by the Company shall be borne by the Company whether or not any
      Registrable Securities are sold pursuant to a Registration Statement. The fees
      and expenses referred to in the foregoing sentence shall include, without
      limitation, (i) all registration and filing fees (including, without limitation,
      fees and expenses (A) with respect to filings required to be made with any
      Trading Market on which the Common Stock is then listed for trading, and (B)
      in
      compliance with applicable state securities or Blue Sky laws), (ii) printing
      expenses (including, without limitation, expenses of printing certificates
      for
      Registrable Securities and of printing prospectuses if the printing of
      prospectuses is reasonably requested by the Investors of a majority of the
      Registrable Securities included in the Registration Statement), (iii) messenger,
      telephone and delivery expenses, (iv) fees and disbursements of counsel for
      the
      Company, (v) Securities Act liability insurance, if the Company so desires
      such
      insurance, and (vi) fees and expenses of all other Persons retained by the
      Company in connection with the consummation of the transactions contemplated
      by
      this Agreement. In addition, the Company shall be responsible for all of its
      internal expenses incurred in connection with the consummation of the
      transactions contemplated by this Agreement (including, without limitation,
      all
      salaries and expenses of its officers and employees performing legal or
      accounting duties), the expense of any annual audit and the fees and expenses
      incurred in connection with the listing of the Registrable Securities on any
      securities exchange as required hereunder.




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5.  Indemnification .




(a)  Indemnification
      by the Company .
      The
      Company shall, notwithstanding any termination of this Agreement, indemnify
      and
      hold harmless each Investor, the officers, directors, agents, investment
      advisors, partners, members, shareholders and employees of each of them, each
      Person who controls any such Investor (within the meaning of Section 15 of
      the
      Securities Act or Section 20 of the Exchange Act) and the officers, directors,
      agents and employees of each such controlling Person, to the fullest extent
      permitted by applicable law, from and against any and all losses, claims,
      damages, liabilities, costs (including, without limitation, reasonable costs
      of
      preparation and reasonable attorneys' fees) and expenses (collectively, **“Losses”** ),
      as
      incurred, arising out of or relating to any untrue or alleged untrue statement
      of a material fact contained in any Registration Statement, any Prospectus
      or
      any form of prospectus or in any amendment or supplement thereto or in any
      preliminary prospectus, or arising out of or relating to any omission or alleged
      omission of a material fact required to be stated therein or necessary to make
      the statements therein (in the case of any Prospectus or form of prospectus
      or
      supplement thereto, in light of the circumstances under which they were made)
      not misleading, except to the extent, but only to the extent, that (1) such
      untrue statements or omissions are based solely upon information regarding
      such
      Investor furnished in writing to the Company by such Investor expressly for
      use
      therein, or to the extent that such information relates to such Investor or
      such
      Investor's proposed method of distribution of Registrable Securities and was
      reviewed and expressly approved in writing by such Investor expressly for use
      in
      the Registration Statement, such Prospectus or such form of Prospectus or in
      any
      amendment or supplement thereto (it being understood that the Investor has
      approved Annex A hereto for this purpose) or (2) in the case of an occurrence
      of
      an event of the type specified in Section 3(b)(ii)-(v), the use by such Investor
      of an outdated or defective Prospectus after the Company has notified such
      Investor in writing that the Prospectus is outdated or defective and prior
      to
      the receipt by such Investor of an Advice or an amended or supplemented
      Prospectus, but only if and to the extent that following the receipt of the
      Advice or the amended or supplemented Prospectus the misstatement or omission
      giving rise to such Loss would have been corrected. The Company shall notify
      the
      Investors promptly of the institution, threat or assertion of any Proceeding
      of
      which the Company is aware in connection with the transactions contemplated
      by
      this Agreement.




(b)  Indemnification
      by Investors .
      Each
      Investor shall, severally and not jointly, indemnify and hold harmless the
      Company, its directors, officers, agents and employees, each Person who controls
      the Company (within the meaning of Section 15 of the Securities Act and Section
      20 of the Exchange Act), and the directors, officers, agents or employees of
      such controlling Persons, to the fullest extent permitted by applicable law,
      from and against all Losses, as incurred, arising solely out of or based solely
      upon: (x) such Investor's failure to comply with the prospectus delivery
      requirements of the Securities Act or (y) any untrue statement of a material
      fact contained in any Registration Statement, any Prospectus, or any form of
      prospectus, or in any amendment or supplement thereto, or arising solely out
      of
      or based solely upon any omission of a material fact required to be stated
      therein or necessary to make the statements therein not misleading to the
      extent, but only to the extent that, (1) such untrue statements or omissions
      are
      based solely upon information regarding such Investor furnished in writing
      to
      the Company by such Investor expressly for use therein, or to the extent that
      such information relates to such Investor or such Investor's proposed method
      of
      distribution of Registrable Securities and was reviewed and expressly approved
      in writing by such Investor expressly for use in the Registration Statement
      (it
      being understood that the Investor has approved Annex A hereto for this
      purpose), such Prospectus or such form of Prospectus or in any amendment or
      supplement thereto or (2) in the case of an occurrence of an event of the type
      specified in Section 3(b)(ii)-(v), the use by such Investor of an outdated
      or
      defective Prospectus after the Company has notified such Investor in writing
      that the Prospectus is outdated or defective and prior to the receipt by such
      Investor of an Advice or an amended or supplemented Prospectus, but only if
      and
      to the extent that following the receipt of the Advice or the amended or
      supplemented Prospectus the misstatement or omission giving rise to such Loss
      would have been corrected. In no event shall the liability of any selling
      Investor hereunder be greater in amount than the dollar amount of the net
      proceeds received by such Investor upon the sale of the Registrable Securities
      giving rise to such indemnification obligation.




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(c)  Conduct
      of Indemnification Proceedings .
      If any
      Proceeding shall be brought or asserted against any Person entitled to indemnity
      hereunder (an **“Indemnified
      Party”** ),
      such
      Indemnified Party shall promptly notify the Person from whom indemnity is sought
      (the **“Indemnifying
      Party”** )
      in
      writing, and the Indemnifying Party shall assume the defense thereof, including
      the employment of counsel reasonably satisfactory to the Indemnified Party
      and
      the payment of all fees and expenses incurred in connection with defense
      thereof; provided, that the failure of any Indemnified Party to give such notice
      shall not relieve the Indemnifying Party of its obligations or liabilities
      pursuant to this Agreement, except (and only) to the extent that it shall be
      finally determined by a court of competent jurisdiction (which determination
      is
      not subject to appeal or further review) that such failure shall have
      proximately and materially adversely prejudiced the Indemnifying
      Party.




An
      Indemnified Party shall have the right to employ separate counsel in any such
      Proceeding and to participate in the defense thereof, but the fees and expenses
      of such counsel shall be at the expense of such Indemnified Party or Parties
      unless: (1) the Indemnifying Party has agreed in writing to pay such fees and
      expenses; (2) the Indemnifying Party shall have failed promptly to assume the
      defense of such Proceeding and to employ counsel reasonably satisfactory to
      such
      Indemnified Party in any such Proceeding; or (3) the named parties to any such
      Proceeding (including any impleaded parties) include both such Indemnified
      Party
      and the Indemnifying Party, and such Indemnified Party shall have been advised
      by counsel that a conflict of interest is likely to exist if the same counsel
      were to represent such Indemnified Party and the Indemnifying Party (in which
      case, if such Indemnified Party notifies the Indemnifying Party in writing
      that
      it elects to employ separate counsel at the expense of the Indemnifying Party,
      the Indemnifying Party shall not have the right to assume the defense thereof
      and such counsel shall be at the expense of the Indemnifying Party). The
      Indemnifying Party shall not be liable for any settlement of any such Proceeding
      effected without its written consent, which consent shall not be unreasonably
      withheld. No Indemnifying Party shall, without the prior written consent of
      the
      Indemnified Party, effect any settlement of any pending Proceeding in respect
      of
      which any Indemnified Party is a party, unless such settlement includes an
      unconditional release of such Indemnified Party from all liability on claims
      that are the subject matter of such Proceeding.




8




All
      reasonable fees and expenses of the Indemnified Party (including reasonable
      fees
      and expenses to the extent incurred in connection with investigating or
      preparing to defend such Proceeding in a manner not inconsistent with this
      Section) shall be paid to the Indemnified Party, as incurred, within ten Trading
      Days of written notice thereof to the Indemnifying Party (regardless of whether
      it is ultimately determined that an Indemnified Party is not entitled to
      indemnification hereunder; provided, that the Indemnifying Party may require
      such Indemnified Party to undertake to reimburse all such fees and expenses
      to
      the extent it is finally judicially determined that such Indemnified Party
      is
      not entitled to indemnification hereunder).




(d)  Contribution .
      If a
      claim for indemnification under Section 5(a) or 5(b) is unavailable to an
      Indemnified Party (by reason of public policy or otherwise), then each
      Indemnifying Party, in lieu of indemnifying such Indemnified Party, shall
      contribute to the amount paid or payable by such Indemnified Party as a result
      of such Losses, in such proportion as is appropriate to reflect the relative
      fault of the Indemnifying Party and Indemnified Party in connection with the
      actions, statements or omissions that resulted in such Losses as well as any
      other relevant equitable considerations. The relative fault of such Indemnifying
      Party and Indemnified Party shall be determined by reference to, among other
      things, whether any action in question, including any untrue or alleged untrue
      statement of a material fact or omission or alleged omission of a material
      fact,
      has been taken or made by, or relates to information supplied by, such
      Indemnifying Party or Indemnified Party, and the parties' relative intent,
      knowledge, access to information and opportunity to correct or prevent such
      action, statement or omission. The amount paid or payable by a party as a result
      of any Losses shall be deemed to include, subject to the limitations set forth
      in Section 5(c), any reasonable attorneys' or other reasonable fees or expenses
      incurred by such party in connection with any Proceeding to the extent such
      party would have been indemnified for such fees or expenses if the
      indemnification provided for in this Section was available to such party in
      accordance with its terms.




The
      parties hereto agree that it would not be just and equitable if contribution
      pursuant to this Section 5(d) were determined by pro rata allocation or by
      any
      other method of allocation that does not take into account the equitable
      considerations referred to in the immediately preceding paragraph.
      Notwithstanding the provisions of this Section 5(d), no Investor shall be
      required to contribute, in the aggregate, any amount in excess of the amount
      by
      which the proceeds actually received by such Investor from the sale of the
      Registrable Securities subject to the Proceeding exceeds the amount of any
      damages that such Investor has otherwise been required to pay by reason of
      such
      untrue or alleged untrue statement or omission or alleged omission.




9




The
      indemnity and contribution agreements contained in this Section are in addition
      to any liability that the Indemnifying Parties may have to the Indemnified
      Parties.




6.  Miscellaneous .




(a)  Remedies .
      In the
      event of a breach by the Company or by a Investor, of any of their obligations
      under this Agreement, each Investor or the Company, as the case may be, in
      addition to being entitled to exercise all rights granted by law and under
      this
      Agreement, including recovery of damages, will be entitled to specific
      performance of its rights under this Agreement. The Company and each Investor
      agree that monetary damages would not provide adequate compensation for any
      losses incurred by reason of a breach by it of any of the provisions of this
      Agreement and hereby further agrees that, in the event of any action for
      specific performance in respect of such breach, it shall waive the defense
      that
      a remedy at law would be adequate.




(b)  Compliance .
      Each
      Investor covenants and agrees that it will comply with the prospectus delivery
      requirements of the Securities Act as applicable to it in connection with sales
      of Registrable Securities pursuant to the Registration Statement.




(c)  Discontinued
      Disposition .
      Each
      Investor agrees by its acquisition of such Registrable Securities that, upon
      receipt of a notice from the Company of the occurrence of any event of the
      kind
      described in Section 3(c), such Investor will forthwith discontinue disposition
      of such Registrable Securities under the Registration Statement until such
      Investor's receipt of the copies of the supplemented Prospectus and/or amended
      Registration Statement or until it is advised in writing (the **“Advice”** )
      by the
      Company that the use of the applicable Prospectus may be resumed, and, in either
      case, has received copies of any additional or supplemental filings that are
      incorporated or deemed to be incorporated by reference in such Prospectus or
      Registration Statement. The Company may provide appropriate stop orders to
      enforce the provisions of this paragraph. The
      Company will use its best efforts to ensure that the use of the Prospectus
      may
      be resumed as promptly as is practicable. The
      Company agrees and acknowledges that any periods during which the Investor
      is
      required to discontinue the disposition of the Registrable Securities hereunder
      shall be subject to the provisions of Section 2(c).





(d)  Piggy-Back
      Registrations .
      If at
      any time during the Effectiveness Period there is not an effective Registration
      Statement covering all of the Registrable Securities and the Company shall
      determine to prepare and file with the Commission a registration statement
      relating to an offering for its own account or the account of others under
      the
      Securities Act of any of its equity securities, other than on Form S-4 or Form
      S-8 (each as promulgated under the Securities Act) 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, then the Company
      shall send to each Investor written notice of such determination and, if within
      fifteen days after receipt of such notice, any such Investor shall so request
      in
      writing, the Company shall include in such registration statement all or any
      part of such Registrable Securities such Investor requests to be registered,
      subject to customary underwriter cutbacks applicable to all holders of
      registration rights.




10




(e)  Amendments
      and Waivers .
      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 the Investors representing at least a majority of
      all
      of the then issued or issuable Notes and Warrants. Notwithstanding the
      foregoing, a waiver or consent to depart from the provisions hereof with respect
      to a matter that relates exclusively to the rights of certain Investors and
      that
      does not directly or indirectly affect the rights of other Investors may be
      given by Investors of at least a majority of the Registrable Securities to
      which
      such waiver or consent relates, provided ,
      that
      the provisions of this sentence may not be amended, modified, or supplemented
      except in accordance with the provisions of the immediately preceding
      sentence.




(f)  Notices .
      Any and
      all notices or other communications or deliveries required or permitted to
      be
      provided hereunder shall be in writing and shall be deemed given and effective
      on the earliest of (i) the date of transmission, if such notice or communication
      is delivered via facsimile at the facsimile telephone number specified in this
      Section prior to 6:30 p.m. (New York City time) on a Trading Day, (ii) the
      Trading Day after the date of transmission, if such notice or communication
      is
      delivered via facsimile at the facsimile telephone number specified in this
      Agreement later than 6:30 p.m. (New York City time) on any date and earlier
      than
      11:59 p.m. (New York City time) on such date, (iii) the Trading Day following
      the date of mailing, if sent by nationally recognized overnight courier service,
      or (iv) upon actual receipt by the party to whom such notice is required to
      be
      given. The address for such notices and communications shall be as
      follows:




If
                  to the Company:
              Calypte
                  Biomedical Corporation5
                  Centerpointe Drive, Suite 400Lake
                  Oswego, OR 97035Facsimile
                  No.: (971) 204-0284Attn:
                  Chief Executive OfficerIf to an
                Investor:
              To the address
                set
                forth under such Investor's name on the signature pages
                hereto





or
      such
      other address as may be designated in writing hereafter, in the same manner,
      by
      such Person.




(g)  Successors
      and Assigns .
      This
      Agreement shall inure to the benefit of and be binding upon the successors
      and
      permitted assigns of each of the parties and shall inure to the benefit of
      each
      Investor. The Company may not assign its rights or obligations hereunder without
      the prior written consent of each Investor. Each Investor may assign its
      respective rights hereunder in the manner and to the Persons as permitted under
      the Subscription Agreement so long as such assignment complies with the
      Subscription Agreement.




11




(h)  Execution
      and Counterparts .
      This
      Agreement 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.




(i)  Governing
      Law .
      All
      questions concerning the construction, validity, enforcement and interpretation
      of this Agreement shall be governed by and construed and enforced in accordance
      with the internal laws of the State of Oregon, without regard to the principles
      of conflicts of law thereof. Each party agrees that all Proceedings concerning
      the interpretations, enforcement and defense of the transactions contemplated
      by
      this Agreement (whether brought against a party hereto or its respective
      Affiliates, employees or agents) shall be commenced exclusively in the state
      and
      federal courts sitting in the City of Portland (the **“Portland
      Courts”** ).
      Each
      party hereto hereby irrevocably submits to the exclusive jurisdiction of the
      Portland Courts for the adjudication of any dispute hereunder or in connection
      herewith or with any transaction contemplated hereby or discussed herein, and
      hereby irrevocably waives, and agrees not to assert in any Proceeding, any
      claim
      that it is not personally subject to the jurisdiction of any Oregon Court,
      or
      that such Proceeding has been commenced in an improper or inconvenient forum.
      Each party hereto hereby irrevocably waives personal service of process and
      consents to process being served in any such Proceeding by mailing a copy
      thereof via registered or certified mail or overnight delivery (with evidence
      of
      delivery) to such party at the address in effect for notices to it under this
      Agreement and agrees that such service shall constitute good and sufficient
      service of process and notice thereof. Nothing contained herein shall be deemed
      to limit in any way any right to serve process in any manner permitted by law.
      Each party hereto hereby irrevocably waives, to the fullest extent permitted
      by
      applicable law, any and all right to trial by jury in any Proceeding arising
      out
      of or relating to this Agreement or the transactions contemplated hereby. If
      either party shall commence a Proceeding to enforce any provisions of this
      Agreement, then the prevailing party in such Proceeding shall be reimbursed
      by
      the other party for its attorney’s fees and other costs and expenses incurred
      with the investigation, preparation and prosecution of such
      Proceeding.




(j)  Cumulative
      Remedies .
      The
      remedies provided herein are cumulative and not exclusive of any remedies
      provided by law.




(k)  Severability .
      If any
      term, provision, covenant or restriction of this Agreement is held by a court
      of
      competent jurisdiction to be invalid, illegal, void or unenforceable, the
      remainder of the terms, provisions, covenants and restrictions set forth herein
      shall remain in full force and effect and shall in no way be affected, impaired
      or invalidated, and the parties hereto shall use their reasonable efforts to
      find and employ an alternative means to achieve the same or substantially the
      same result as that contemplated by such term, provision, covenant or
      restriction. It is hereby stipulated and declared to be the intention of the
      parties that they would have executed the remaining terms, provisions, covenants
      and restrictions without including any of such that may be hereafter declared
      invalid, illegal, void or unenforceable.




12




(l)  Headings .
      The
      headings in this Agreement are for convenience of reference only and shall
      not
      limit or otherwise affect the meaning hereof.




(m)  Independent
      Nature of Investors' Obligations and Rights .
      The
      obligations of each Investor under this Agreement are several and not joint
      with
      the obligations of each other Investor, and no Investor shall be responsible
      in
      any way for the performance of the obligations of any other Investor under
      this
      Agreement. Nothing contained herein or in any Transaction Document, and no
      action taken by any Investor pursuant thereto, shall be deemed to constitute
      the
      Investors as a partnership, an association, a joint venture or any other kind
      of
      entity, or create a presumption that the Investors are in any way acting in
      concert or as a group with respect to such obligations or the transactions
      contemplated by this Agreement or any other Transaction Document. Each Investor
      acknowledges that no other Investor has acted as agent for such Investor in
      connection with making its investment hereunder and that no Investor will be
      acting as agent of such Investor in connection with monitoring its investment
      in
      the Securities or enforcing its rights under the Transaction Documents. Each
      Investor shall be entitled to independently protect and enforce its rights,
      including without limitation the rights arising out of this Agreement, and
      it
      shall not be necessary for any other Investor to be joined as an additional
      party in any Proceeding for such purpose. The Company acknowledges that each
      of
      the Investors has been provided with the same Registration Rights Agreement
      for
      the purpose of closing a transaction with multiple Investors and not because
      it
      was required or requested to do so by any Investor.




[REMAINDER
      OF PAGE INTENTIONALLY LEFT BLANK


SIGNATURE
      PAGES TO FOLLOW]




13




IN
      WITNESS WHEREOF, the parties have executed this Registration Rights Agreement
      as
      of the date first written above.




**CALYPTE
              BIOMEDICAL CORPORATION**By:Name:
                Richard BrounsteinTitle:
              Executive Vice President[REMAINDER OF PAGE INTENTIONALLY LEFT BLANKSIGNATURE PAGES OF INVESTORS TO
              FOLLOW]




14


IN
      WITNESS WHEREOF, the parties have executed this Registration Rights Agreement
      as
      of the date first written above.




**NAME
                  OF INVESTING ENTITY****AUTHORIZED
                  SIGNATORY**By:Name:Title:**ADDRESS
                  FOR NOTICE**c/o:Street:City/State/Zip:Attention:Tel:Fax:Email:






15




Annex
      A




Plan
      of
      Distribution




The
      Selling Stockholders and any of their pledgees, donees, transferees, assignees
      and successors-in-interest may, from time to time, sell any or all of their
      shares of Common Stock on any stock exchange, market or trading facility on
      which the shares are traded or in private transactions. These sales may be
      at
      fixed or negotiated prices. The Selling Stockholders may use any one or more
      of
      the following methods when selling shares:




·
            ordinary
                brokerage transactions and transactions in which the broker-dealer
                solicits Investors;




·
            block
                trades in which the broker-dealer will attempt to sell the shares
                as agent
                but may position and resell a portion of the block as principal to
                facilitate the transaction;




·
            purchases
                by a broker-dealer as principal and resale by the broker-dealer for
                its
                account;




·
            an
                exchange distribution in accordance with the rules of the applicable
                exchange;




·
            privately
                negotiated transactions;




·
            to
                cover short sales made after the date that this Registration Statement
                is
                declared effective by the Commission;




·
            broker-dealers
                may agree with the Selling Stockholders to sell a specified number
                of such
                shares at a stipulated price per
                share;




·
            a
                combination of any such methods of sale;
                and




·
            any
                other method permitted pursuant to applicable
                law.




The
      Selling Stockholders may also sell shares under Rule 144 under the Securities
      Act, if available, rather than under this prospectus.




Broker-dealers
      engaged by the Selling Stockholders may arrange for other brokers-dealers to
      participate in sales. Broker-dealers may receive commissions or discounts from
      the Selling Stockholders (or, if any broker-dealer acts as agent for the
      purchaser of shares, from the purchaser) in amounts to be negotiated. The
      Selling Stockholders do not expect these commissions and discounts to exceed
      what is customary in the types of transactions involved.




The
      Selling Stockholders may from time to time pledge or grant a security interest
      in some or all of the Shares owned by them and, if they default in the
      performance of their secured obligations, the pledgees or secured parties may
      offer and sell shares of Common Stock from time to time under this prospectus,
      or under an amendment to this prospectus under Rule 424(b)(3) or other
      applicable provision of the Securities Act of 1933 amending the list of selling
      stockholders to include the pledgee, transferee or other successors in interest
      as selling stockholders under this prospectus.




16




Upon
      the
      Company being notified in writing by a Selling Stockholder that any material
      arrangement has been entered into with a broker-dealer for the sale of Common
      Stock through a block trade, special offering, exchange distribution or
      secondary distribution or a purchase by a broker or dealer, a supplement to
      this
      prospectus will be filed, if required, pursuant to Rule 424(b) under the
      Securities Act, disclosing (i) the name of each such Selling Stockholder and
      of
      the participating broker-dealer(s), (ii) the number of shares involved, (iii)
      the price at which such the shares of Common Stock were sold, (iv)the
      commissions paid or discounts or concessions allowed to such broker-dealer(s),
      where applicable, (v) that such broker-dealer(s) did not conduct any
      investigation to verify the information set out or incorporated by reference
      in
      this prospectus, and (vi) other facts material to the transaction. In addition,
      upon the Company being notified in writing by a Selling Stockholder that a
      donee
      or pledge intends to sell more than 500 shares of Common Stock, a supplement
      to
      this prospectus will be filed if then required in accordance with applicable
      securities law.




The
      Selling Stockholders also may transfer the shares of Common Stock in other
      circumstances, in which case the transferees, pledgees or other successors
      in
      interest will be the selling beneficial owners for purposes of this
      prospectus.




The
      Selling Stockholders and any broker-dealers or agents that are involved in
      selling the shares may be deemed to be “underwriters” within the meaning of the
      Securities Act in connection with such sales. In such event, any commissions
      received by such broker-dealers or agents and any profit on the resale of the
      shares purchased by them may be deemed to be underwriting commissions or
      discounts under the Securities Act. Discounts, concessions, commissions and
      similar selling expenses, if any, that can be attributed to the sale of
      Securities will be paid by the Selling Stockholder and/or the purchasers. Each
      Selling Stockholder has represented and warranted to the Company that it
      acquired the securities subject to this registration statement in the ordinary
      course of such Selling Stockholder’s business and, at the time of its purchase
      of such securities such Selling Stockholder had no agreements or understandings,
      directly or indirectly, with any person to distribute any such securities.




Each
      Selling Stockholder has acknowledged that Shares registered on this Registration
      Statement may not be used to cover short sales of Common Stock made prior to
      the
      date on which this Registration Statement shall have been declared effective
      by
      the Commission. If a Selling Stockholder uses this prospectus for any sale
      of
      the Common Stock, it will be subject to the prospectus delivery requirements
      of
      the Securities Act. The Selling Stockholders will be responsible to comply
      with
      the applicable provisions of the Securities Act and Exchange Act, and the rules
      and regulations thereunder promulgated, including, without limitation,
      Regulation M, as applicable to such Selling Stockholders in connection with
      resales of their respective shares under this Registration
      Statement.




17




The
      Company is required to pay all fees and expenses incident to the registration
      of
      the shares, but the Company will not receive any proceeds from the sale of
      the
      Common Stock. The Company has agreed to indemnify the Selling Stockholders
      against certain losses, claims, damages and liabilities, including liabilities
      under the Securities Act.




18




Annex
      B




CALYPTE
      BIOMEDICAL CORPORATION




**Selling
      Securityholder Notice and Questionnaire**




The
      undersigned beneficial owner of common stock (the **“Common
      Stock”** ),
      of **Calypte
      Biomedical Corporation** (the **“Company”** )
      understands that the Company has filed or intends to file with the Securities
      and Exchange Commission (the **“Commission”** )
      a
      Registration Statement for the registration and resale of the Registrable
      Securities, in accordance with the terms of the Registration Rights Agreement,
      dated as of February [ ], 2007(the **“Registration
      Rights Agreement”** ),
      among
      the Company and the Investors named therein. A copy of the Registration Rights
      Agreement is available from the Company upon request at the address set forth
      below. All capitalized terms used and not otherwise defined herein shall have
      the meanings ascribed thereto in the Registration Rights Agreement.




The
      undersigned hereby provides the following information to the Company and
      represents and warrants that such information is accurate:




**QUESTIONNAIRE**


**1.**
              **Name.**(a)
              Full
                  Legal Name of Selling Securityholder(b)
              Full
                  Legal Name of Registered Holder (if not the same as (a) above)
                  through
                  which Registrable Securities Listed in Item 3 below are held:(c)
              Full
                  Legal Name of Natural Control Person (which means a natural person
                  who
                  directly or indirectly alone or with others has power to vote or
                  dispose
                  of the securities covered by the questionnaire):**2. 
Address
                for Notices to Selling
                Securityholder:**


Telephone:Fax:Contact
              Person:




19




**3.  Beneficial
              Ownership of Registrable Securities:**Type
              and Principal Amount of Registrable Securities beneficially
              owned:








**4.
      Broker-Dealer Status:**




(a)
            Are
                you a broker-dealer?




Yes
o  No
o




Note:
            If
                yes, the Commission’s staff has indicated that you should be identified as
                an underwriter in the Registration
                Statement.




(b)
            Are
                you an affiliate of a
                broker-dealer?




Yes
oNo
o




(c)
            If
                you are an affiliate of a broker-dealer, do you certify that you
                bought
                the Registrable Securities in the ordinary course of business, and
                at the
                time of the purchase of the Registrable Securities to be resold,
                you had
                no agreements or understandings, directly or indirectly, with any
                person
                to distribute the Registrable
                Securities?




Yes
oNo
o




Note:
            If
                no, the Commission’s staff has indicated that you should be identified as
                an underwriter in the Registration
                Statement.




**5.
      Beneficial Ownership of Other Securities of the Company Owned by the Selling
      Securityholder.**




*Except
      as set forth below in this Item 5, the undersigned is not the beneficial or
      registered owner of any securities of the Company other than the Registrable
      Securities listed above in Item 3.*




Type
                and Amount of Other Securities beneficially owned by the Selling
                Securityholder:








20




**6.
      Relationships with the Company:**




*Except
      as set forth below, neither the undersigned nor any of its affiliates, officers,
      directors or principal equity holders (owners of 5% of more of the equity
      securities of the undersigned) has held any position or office or has had any
      other material relationship with the Company (or its predecessors or affiliates)
      during the past three years.*




State
      any
      exceptions here:












The
      undersigned agrees to promptly notify the Company of any inaccuracies or changes
      in the information provided herein that may occur subsequent to the date hereof
      and prior to the Effective Date for the Registration Statement.




By
      signing below, the undersigned consents to the disclosure of the information
      contained herein in its answers to Items 1 through 6 and the inclusion of such
      information in the Registration Statement and the related prospectus. The
      undersigned understands that such information will be relied upon by the Company
      in connection with the preparation or amendment of the Registration Statement
      and the related prospectus.




IN
      WITNESS WHEREOF the undersigned, by authority duly given, has caused this Notice
      and Questionnaire to be executed and delivered either in person or by its duly
      authorized agent.


Dated:
              
              
              Beneficial
                Owner:By:Name:Title:





**PLEASE
      FAX A COPY OF THE COMPLETED AND EXECUTED NOTICE AND QUESTIONNAIRE, AND RETURN
      THE ORIGINAL BY OVERNIGHT MAIL,**





**TO:**  **CALYPTE
      BIOMEDICAL CORPORATION**


925-905-3836




21