CALYPTE BIOMEDICAL CORP
S-3, 1997-10-21
LABORATORY ANALYTICAL INSTRUMENTS
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<PAGE>
 
       As filed with the Securities and Exchange Commission on October 21, 1997
                                                              
                                                           Registration No. 333-
================================================================================

                      SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, DC 20549

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

                                   FORM S-3
                            REGISTRATION STATEMENT
                                     UNDER
                          THE SECURITIES ACT OF 1933

                        CALYPTE BIOMEDICAL CORPORATION
            (Exact name of registrant as specified in its charter)

          DELAWARE                     3826                     06-1226727
      (State or other           (Primary Standard            (I.R.S. employer 
        jurisdiction                Industrial                 identification
      of incorporation            Classification                  number)
      or organization)             Code Number)

        1440 FOURTH STREET, BERKELEY, CALIFORNIA 94710, (510) 526-2541
  (Address, including zip code, and telephone number, including area code, of
                   registrant's principal executive offices)

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

                                 JOHN P. DAVIS
                     President and Chief Executive Officer
                        Calypte Biomedical Corporation
                              1440 Fourth Street
                          Berkeley, California  94710
                                (510) 526-2541

          (Name, address, including zip code, and telephone number, 
                  including area code, of agent for service)

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

                                  Copies to:

                            RICHARD FRIEDMAN, ESQ.
                        Heller Ehrman White & McAuliffe
                             525 University Avenue
                          Palo Alto, California 94301
                             (650) 324-7000(phone)
                             (650) 324-0638 (fax)

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

       APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC:
As soon as practicable after the effective date of this Registration Statement.

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

If the only securities being registered on this Form are being offered pursuant
to dividend or interest reinvestment plans, please check the following box. [_]

If any of the securities being registered on this Form are to be offered on a
delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, as amended, other than securities offered only in connection with dividend
or interest reinvestment plans, check the following box. [X]

If this Form is filed to register additional securities for an offering pursuant
to Rule 462(b) under the Securities Act of 1933, as amended, please check the
following box and list the Securities Act registration statement number of the
earlier effective registration statement for the same offering. [_] ____________
        
If this Form is a post-effective amendment filed pursuant to Rule 462(c) under
the Securities Act of 1933, as amended, check the following box and list the
Securities Act registration statement number of the earlier effective
registration statement for the same offering. [_] _____________
                                                 

If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. [_]

                        CALCULATION OF REGISTRATION FEE
<TABLE> 
<CAPTION> 
================================================================================================================
                                                          Proposed              Proposed             
                                        Amount            Maximum               Maximum       
Title of Shares to be Registered        to be           Offering Price          Aggregate          Amount of 
                                      Registered        Per Share (1)         Offering Price    Registration Fee
- ----------------------------------------------------------------------------------------------------------------
<S>                                   <C>               <C>                   <C>                <C> 
Common Stock, $.001 par value...      2,600,999           $5.06               $13,161,055        $3,989
================================================================================================================
</TABLE> 
(1)  Estimated in accordance with Rule 457(c) for the purpose of computing the
     amount of the registration fee based on the average of the high and low
     prices of the Company's Common Stock on the Nasdaq SmallCap Market on
     October 15, 1997.

THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR DATES
AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL FILE
A FURTHER AMENDMENT THAT SPECIFICALLY STATES THAT THIS REGISTRATION STATEMENT
SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(a) OF THE
SECURITIES ACT OF 1933 OR UNTIL THIS REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE SECURITIES AND EXCHANGE COMMISSION, ACTING
PURSUANT TO SAID SECTION 8(a), MAY DETERMINE.
<PAGE>

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+INFORMATION CONTAINED HEREIN IS SUBJECT TO COMPLETION OR AMENDMENT. A         +
+REGISTRATION STATEMENT RELATING TO THESE SECURITIES HAS BEEN FILED WITH THE   +
+SECURITIES AND EXCHANGE COMMISSION. THESE SECURITIES MAY NOT BE SOLD NOR MAY  +
+OFFERS TO BUY BE ACCEPTED PRIOR TO THE TIME THE REGISTRATION STATEMENT        +
+BECOMES EFFECTIVE. THIS PROSPECTUS SHALL NOT CONSTITUTE AN OFFER TO SELL OR   +
+THE SOLICITATION OF AN OFFER TO BUY NOR SHALL THERE BE ANY SALE OF THESE      +
+SECURITIES IN ANY STATE IN WHICH SUCH OFFER, SOLICITATION OR SALE WOULD BE    +
+UNLAWFUL PRIOR TO REGISTRATION OR QUALIFICATION UNDER THE SECURITIES LAWS OF  +
+ANY SUCH STATE.                                                               +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


                SUBJECT TO COMPLETION, DATED OCTOBER 21, 1997

PROSPECTUS
- ----------
                        CALYPTE BIOMEDICAL CORPORATION
                       2,600,999 Shares of Common Stock


        All of the 2,600,999 shares (the "Shares") of common stock, $.001 par
value (the "Common Stock"), of Calypte Biomedical Corporation ("Calypte" or the
"Company") covered by this Prospectus are being offered by the holders of the
Shares (collectively, the "Selling Stockholders") named in this Prospectus, each
of whom acquired such Shares pursuant to an exemption from the registration
requirements of the Securities Act of 1933, as amended (the "Securities Act"),
provided by Section 4(2) thereof. The Shares are being registered by the Company
pursuant to the terms of that certain Stock Purchase Agreement, dated October
17, 1997, by and between the Company and the individual Selling Stockholders
(the "Purchase Agreement"). See "Selling Stockholders."

        Some or all of the Shares covered by this Prospectus may be offered for
sale from time to time by the Selling Stockholders at such prices and on such
terms as may then be obtainable, in negotiated transactions, or otherwise. This
Prospectus may be used by the Selling Stockholders or by any broker-dealer who
may participate in sales of the securities covered hereby. The Selling
Stockholders will pay all commissions, transfer taxes and other expenses
associated with the sales of securities by them. The Company has paid the
expenses of the preparation of this Prospectus. The Company has agreed to
indemnify the Selling Stockholders against certain liabilities, including
liabilities arising under the Securities Act. The Company will not receive any
of the proceeds from the sale of Shares by the Selling Stockholders.

        The Shares are quoted on the Nasdaq SmallCap Market under the symbol 
"CALY." On October 20, 1997, the closing price as reported on the Nasdaq
SmallCap Market was $5.13 per share.

        Calypte has filed with the Securities and Exchange Commission (the
"Commission") a Registration Statement under the Securities Act of 1933, as
amended (the "Securities Act"), with respect to the securities offered by this
Prospectus. As permitted by the rules and regulations of the Commission, this
Prospectus does not contain all of the information set forth in the Registration
Statement and the exhibits and schedules thereto. For further information with
respect to Calypte and the securities offered hereby, reference is made to the
Registration Statement and the exhibits thereto, which may be examined without
charge at the public reference facilities maintained by the Commission at
Judiciary Plaza, 450 Fifth Street, N.W., Washington, D.C. 20549, and copies of
which may be obtained from the Commission upon payment of the prescribed fees.



         THE SECURITIES OFFERED HEREBY INVOLVE A HIGH DEGREE OF RISK.
                    SEE "RISK FACTORS" BEGINNING ON PAGE 3.


   THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES
        AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR
            HAS THE SECURITIES AND EXCHANGE COMMISSION OR ANY STATE
                SECURITIES COMMISSION PASSED UPON THE ACCURACY
                     OR ADEQUACY OF THIS PROSPECTUS.  ANY
                        REPRESENTATION TO THE CONTRARY
                            IS A CRIMINAL OFFENSE.



            THE DATE OF THIS PROSPECTUS IS _______________, 1997
<PAGE>
 
        No person is authorized to give any information or to make any
representations other than those contained or incorporated by reference in this
Prospectus and, if given or made, such information or representations must not
be relied upon as having been authorized. This Prospectus does not constitute an
offer of any securities other than those to which it relates or an offer to any
person in any jurisdiction where such offer would be unlawful. The delivery of
this Prospectus at any time does not imply that the information herein is
correct as of any time subsequent to the date hereof.


                             AVAILABLE INFORMATION

        The Company is subject to the informational requirements of the
Securities Exchange Act of 1934, as amended (the "Exchange Act"), and in
accordance therewith files reports and other information with the Commission.
Reports, proxy and information statements and other information filed by the
Company with the Commission can be inspected and copied at the public reference
facilities maintained by the Commission at the following addresses: New York
Regional Office, Seven World Trade Center, New York, New York 10048 and Chicago
Regional Office, Northwestern Atrium Center, 500 West Madison Street, Chicago,
Illinois 60661-2511. Copies of such material can be obtained from the Public
Reference Section of the Commission at Judiciary Plaza, 450 Fifth Street, N.W.,
Washington, D.C. 20549 at prescribed rates. The Commission maintains a Web site
that contains reports, proxy and other information regarding issuers that file
electronically with the Commission. The address of such Web site is
http://www.sec.gov.


                      DOCUMENTS INCORPORATED BY REFERENCE

        The following documents filed by the Company with the Commission are
incorporated in this Prospectus by reference:

        (i)   the Company's annual report on Form 10-K for the fiscal year ended
December 31, 1996;

        (ii)  the Company's Quarterly Reports on Form 10-Q for the fiscal
quarters ended March 31, 1997 and June 30, 1997; and

        (iii) the description of the Company's Common Stock contained in its
Registration Statement on Form 8-A filed pursuant to Section 12 of the Exchange
Act on July 10, 1996.

        All documents subsequently filed by the Company pursuant to Sections
13(a), 13(c), 14 or 15(d) of the Exchange Act prior to the termination of the
offering of securities thereunder shall be deemed to be incorporated herein by
reference and shall be a part hereof from the date of the filing of such
documents. Any statements contained in a document incorporated or deemed to be
incorporated by reference herein shall be deemed to be modified or replaced for
purposes of this Prospectus to the extent that a statement contained herein or
in any other subsequently filed document which also is or is deemed to be
incorporated by reference herein modifies or replaces such statement. Any such
statement so modified or replaced shall not be deemed, except as so modified or
replaced, to constitute a part of this Prospectus.

        The Company will provide without charge to each person, including any
beneficial owner, to whom a Prospectus is delivered, upon written or oral
request of such person, a copy of any document incorporated by reference in this
Prospectus, other than exhibits to such documents not specifically incorporated
by reference. Such requests should be directed to 1440 Fourth Street, Berkeley,
California 94710, Attention: President, telephone (510) 526-2541.

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

                                       2
<PAGE>
 
                             RECENT DEVELOPMENTS 

        On September 18, 1997, Cambridge Biotech Corporation ("Cambridge
Biotech") received official notice from the U.S. Food and Drug Administration
(the "FDA") that the agency had completed its review of Cambridge Biotech's
application supplement for its Human Immunodeficiency Virus Type 1 ("HIV-1")
Western Blot kit for use with urine samples. The FDA "Review Complete" letter
indicated that the kit may be marketed once the Company has addressed the
labeling issues posed in the "Review Complete" letter and the product labeling
review process has been completed. The Urine HIV-1 Western Blot is a urine
confirmation test manufactured by Cambridge Biotech, a wholly owned subsidiary
of bioMerieux Vitek Inc. under a license from Calypte. The Urine HIV-1
confirmation test will be marketed as soon as the product's labeling is
finalized and approved by the FDA. There can be no assurance that the FDA will
grant approval of the Cambridge Biotech urine confirmatory test.

                                 RISK FACTORS

        The Company wishes to caution readers that the following important
factors, among others, may affect the Company's future results, events or
performance and could cause actual results, events or performance to differ
materially from those expressed in any forward-looking statements made by the
Company in this report or presented elsewhere by the Company from time to time.

        Dependence on Sole Source of Supply and Regulatory Approval of
        --------------------------------------------------------------
Confirmatory Test.  In order to minimize the possibility of false positive
- -----------------
reports, positive HIV screening results must be confirmed with an additional
test format before being reported to the physician or patient in the United
States and in most developed countries. The Company has entered into an
agreement with Cambridge Biotech under which both the Company and Cambridge
Biotech will market and distribute a urine-capable western blot confirmatory
test which uses technology licensed from the Company. The western blot kit
manufactured by Cambridge Biotech has already received FDA approval for blood
testing, and is the only confirmatory test for which application has been made
for FDA approval for use with urine. On September 18, 1997, Cambridge Biotech
received official notice from the FDA that the FDA had completed its review of
the HIV-1 western blot kit. Such notice indicated that Cambridge Biotech's
application was approvable pending the completion of product labeling. There can
be no assurance that the FDA will grant approval of the Cambridge Biotech urine
confirmatory test. Any significant delay in obtaining approval for the Cambridge
Biotech urine confirmatory test or the failure to obtain such approval at all
could have a material adverse effect on the Company's business, financial
condition and results of operations.

        Reliance on Proprietary Technology and Know-How; License Obligations.
        --------------------------------------------------------------------
The Company believes that its future success will depend in large part on its
ability to protect its patents and proprietary rights. Accordingly, the
Company's ability to compete effectively will depend in part on its ability to
develop and maintain proprietary aspects of its technology. In addition, the
Company has the right to utilize certain patents and proprietary rights under
licensing agreements with New York University, Cambridge Biotech, Repligen,
Texas A&M University System and Stanford University. These license arrangements
secure intellectual property rights for the manufacture and sale of the
Company's products. There can be no assurance that such intellectual property
rights will be sufficient or that such patents and proprietary rights can be
adequately protected.

        Uncertainty of Market Acceptance; Lack of Sales and Marketing
        -------------------------------------------------------------
Experience.  The Company's products represent a new method of determining the
- ----------
presence of HIV antibodies and there can be no assurance that these products
will gain any significant degree of market acceptance among physicians,
patients, or health care payors, even if necessary international and U.S.
regulatory and reimbursement approvals are obtained. The Company believes that
recommendations and endorsements by the medical community will be essential for
market acceptance of the products, and there can be no assurance that any such
recommendations or endorsements will be obtained. The Company has no experience
marketing and selling its products either directly or through its distributors.
The Company's marketing strategy relies upon its alliance with third-party
distributors for the success of its products. There can be no assurance that the
Company's direct sales force 

                                       3
<PAGE>
 
will be effective, that its distributors will market successfully the Company's
products or that, if such relationships are terminated, the Company will be able
to establish relationships with other distributors on satisfactory terms, if at
all. Any disruption in the Company's distribution, sales or marketing network,
or failure of the Company's products to achieve market acceptance, could have a
material adverse effect on the Company's business, financial condition and
results of operations.

        Dependence on a Single Product.  The Company's HIV-1 urine-based
        ------------------------------
screening test is the Company's only FDA-approved product. Because the screening
test is the Company's sole product, the Company could be required to cease
operations if Cambridge Biotech's confirmatory test does not receive FDA
approval or if the Company's test, together with the Cambridge Biotech urine
confirmatory test, fails to achieve market acceptance or generate significant
revenue.

        Dependence Upon Key Suppliers.  The Company purchases raw materials and
        -----------------------------
components used in the manufacture of its product from various suppliers and
relies on single sources for several of these components.  Establishment of
additional or replacement suppliers for these components cannot be accomplished
quickly.  The Company has a number of single-source components, and any delay or
interruption in supply of these components could significantly impair the
Company's ability to manufacture its products in sufficient quantities, and
therefore would have a material adverse effect on the Company's business,
financial condition and results of operations, particularly as the Company
scales up its manufacturing activities in support of commercial sales.

        Limited Manufacturing Experience; Scale-Up Risk. The Company has limited
        -----------------------------------------------
experience in manufacturing its products. The Company currently manufactures its
products in limited quantities for submission to the FDA for ongoing compliance,
international clinical trials and building its inventory in anticipation of
commercialization. The Company does not have experience in manufacturing its
products in commercial quantities. Manufacturers often encounter difficulties in
scaling-up production of new products, including problems involving production
yields, quality control and assurance, raw material supply and shortages of
qualified personnel. The larger Alameda facility will be needed if initial
demand exceeds the more limited capacity of the Berkeley facility. Difficulties
encountered by the Company in manufacturing scale-up to meet demand, including
delays in receiving FDA approval for the Alameda facility, could have a material
adverse effect on its business, financial condition and results of operations.

        Dependence Upon International Distributors and Sales. The Company
        ----------------------------------------------------
anticipates that a significant portion of its revenues for the next several
years will be derived from international distributor sales. International sales
and operations involve a number of inherent risks and may be limited or
disrupted by the imposition of government controls, export license requirements,
political instability, trade restrictions, changes in tariffs, difficulties in
managing international operations and fluctuations in foreign currency exchange
rates. Certain of the Company's distributors have limited international
marketing experience, and there can be no assurance that the Company's
distributors will be able to market successfully the Company's products in any
international market.

        Intense Competition in Company's Markets and Rapid Technological
        ----------------------------------------------------------------
Advances by Competitors.  Competition in the in vitro diagnostic market is
- -----------------------
intense and is expected to increase. Within the United States, the Company will
face competition from a number of well-established manufacturers of blood-based
enzyme immunoassays, plus at least one system for the detection of HIV
antibodies using oral fluid samples. In addition, the Company may face intense
competition from competitors with significantly greater financial, marketing and
distribution resources than the Company, several of whom may have already
submitted applications to the FDA for approval of their over-the-counter (OTC)
products. There can no assurance that the Company's competitors will not succeed
in developing or marketing technologies and products that are more effective
than those developed by the Company or that would render the Company's
technologies or products obsolete or otherwise commercially unattractive. In
addition, there can be no assurance that competitors will not succeed in
obtaining regulatory approval for such products, or introducing or
commercializing them prior to the Company. Such developments could have a
material adverse effect on the Company's business, financial condition and
results of operations.

        Potential Fluctuations in Quarterly Results. The Company expects that
        -------------------------------------------
its revenues and results of operations may fluctuate significantly from quarter
to quarter and will depend on a number of factors, many of which are outside the
Company's control. These factors include actions relating to regulatory matters,
the extent to which the Company's products gain market acceptance, the timing
and size of distributor purchases, introduction of alternative means for testing
for HIV, competition, the timing and cost of new product introductions, and
general economic conditions.

                                       4
<PAGE>
 
        Extensive Government Regulation.  The Company's products are subject to
        -------------------------------
extensive regulation by the FDA and, to varying degrees, by state and foreign
regulatory agencies. The Company's products are regulated by the FDA under the
Federal Food, Drug and Cosmetic Act (the "Act"), as amended by the Medical
Device Amendments of 1976 and the Safe Medical Devices Act of 1990, among other
laws. Under the Act, the FDA regulates the preclinical and clinical testing,
manufacturing, labeling, distribution, sale and promotion of medical devices in
the United States. The FDA prohibits a device, whether or not cleared under a
510(k) premarket notification or approved under a pre-market application, from
being marketed for unapproved clinical uses. If the FDA believes that a company
is not in compliance with the regulations, it can institute proceedings to
detain or seize a product, issue a recall, prohibit marketing and sales of such
company's products and assess civil and criminal penalties against such company,
its officers or its employees. Furthermore, the Company plans to sell products
in certain foreign countries which impose local regulatory requirements. The
preparation of required applications and subsequent FDA and foreign regulatory
approval process is expensive, lengthy and uncertain. Failure to comply with FDA
and similar foreign requirements could result in civil monetary penalties or
criminal sanctions, restrictions on or injunctions against marketing of the
Company's products. Additional enforcement actions potentially may include
seizure or recall of the Company's products, and other regulatory action. There
can be no assurance that the Company will be able to obtain necessary regulatory
approvals or clearances in a timely manner or at all, and delays in receipt of
or failure to receive such approvals or clearances, loss of previously received
approvals or clearances, or failure to comply with existing or future regulatory
requirements would have a material adverse effect on the Company's business,
financial condition and results of operations.

        Establishment and Regulation of Reference Laboratory.  The Company
        ----------------------------------------------------
intends to establish a clinical reference laboratory in connection with seeking
approval for an OTC home urine collection kit for HIV-1. There are a number of
risks in establishing a reference laboratory especially for testing for HIV. The
Company must, among other actions, seek to hire and retain key laboratory
personnel, purchase necessary equipment, secure required permits, incur
marketing expenses, obtain customers, and comply with government regulations.
The Company's planned laboratory would test for HIV using the Company's urine-
based HIV-1 test and, if approvals are obtained, receive home collected urine
for HIV testing. The Company may be required to offer counseling in connection
with the reporting of results to laboratory customers. There can be no assurance
that the Company can establish or receive the necessary approval for the
laboratory.

        Product Liability and Recall Risk; Limited Insurance Coverage. The
        -------------------------------------------------------------
manufacture and sale of medical diagnostic products entail the risk of product
liability claims or product recalls. While the Company maintains product
liability insurance, the Company faces the risk of litigation in the event of
false positive or false negative reports. There can be no assurance that the
Company's existing insurance coverage limits will be adequate to protect the
Company from any liabilities it might incur in connection with the clinical
trials or sales of its products. In addition, the Company may require increased
product liability coverage as its products are commercialized. Such insurance is
expensive and in the future may not be available on acceptable terms, if at all.
A successful product liability claim or series of claims brought against the
Company in excess of its insurance coverage, or a recall of the Company's
products, could have a material adverse effect on the Company's business,
financial condition and results of operations.

        Dependence Upon Key Personnel. The Company is dependent upon a number of
        -----------------------------
key management and technical personnel. The Company has employment agreements
with some members of its core management team. The Company's ability to manage
its transition to commercial-scale operations, and hence its success, will
depend on the efforts of these individuals, among others. The loss of the
services of one or more key employees could have a material adverse effect on
the Company. The Company's success will also depend on its ability to attract
and retain additional highly qualified management and technical personnel. The
Company faces intense competition for qualified personnel, many of whom are
often subject to competing employment offers, and there can be no assurance that
the Company will be able to attract and retain such personnel.

        Control by Directors, Executive Officers and Affiliated Entities.  The
        ----------------------------------------------------------------
Company's directors, executive officers and entities affiliated with them, in
the aggregate, beneficially own approximately 35% of the Company's outstanding
Common Stock. Accordingly, these stockholders, individually and as a group, may
be able to substantially influence the outcome of matters requiring approval by
the stockholders of the Company, including the election of directors and the
approval of mergers or other business combination transactions.

        Possible Volatility of Stock Price.  There can be no assurance than an
        ----------------------------------
active trading market will be maintained in the Company's Common Stock. The
Company's Common Stock is listed on the NASDAQ SmallCap Market System. The

                                       5
<PAGE>
 
stock market has from time to time experienced significant price and volume
fluctuations that are unrelated to the operating performance of particular
companies. These broad market fluctuations may adversely affect the market price
of the Company's Common Stock. In addition, the market price of the shares of
Common Stock is likely to be highly volatile. Factors such as fluctuations in
the Company's operating results, announcements of technological innovations or
new products by the Company or its competitors, FDA and international regulatory
actions, actions with respect to reimbursement matters, developments with
respect to patents or proprietary rights, public concern as to the safety of
products developed by the Company or others, changes in health care policy in
the United States. and internationally, changes in stock market analysts'
recommendations regarding the Company, other medical products companies or the
medical product industry generally and general market conditions may have a
significant effect on the market price of the Common Stock.

        Potential Adverse Effect on Market Price of Shares Eligible for Future
        ----------------------------------------------------------------------
Sale.  Substantially all of the shares of the Company's outstanding Common Stock
- ----
are freely tradable. Sales of Common Stock (including shares issued upon the
exercise of outstanding options) in the public market could materially adversely
affect the market price of the Common Stock. Such sales also might make it more
difficult for the Company to sell equity securities or equity-related securities
in the future at a time and price that the Company deems appropriate.

        Anti-Takeover Effect of Certain Charter Provisions.  Certain provisions
        --------------------------------------------------
of the Company's Certificate of Incorporation and Bylaws could discourage
potential acquisition proposals and could delay or prevent a change in control
of the Company. Such provisions could diminish the opportunities for a
stockholder to participate in tender offers, including tender offers at a price
above the then current market value of the Common Stock. Such provisions may
also inhibit increases in the market price of the Common Stock that could result
from takeover attempts. In addition, the Board of Directors of the Company,
without further stockholder approval, may issue preferred stock with such terms
as the Board of Directors may determine, that could have the effect of delaying
or preventing a change in control of the Company. The issuance of preferred
stock could also adversely affect the voting power of the holders of Common
Stock, including the loss of voting control to others.


                                       6
<PAGE>
 
                                CAPITALIZATION

        The following table sets forth the actual capitalization of the Company
at June 30, 1997 and the actual capitalization pro forma and as adjusted
assuming the sale by the Company of 2,600,999 shares of Common Stock pursuant to
the Purchase Agreement at a price of $4.25 per share and the application of the
net proceeds therefrom (after deduction of estimated commissions and estimated
offering expenses).

<TABLE>
<CAPTION>

                                                                            June 30, 1997
                                                                -----------------------------------------
                                                                                           Pro Forma
                                                                                             and As
                                                                      Actual               Adjusted(1)
                                                                ------------------      ------------------
                                                                       (in thousands, except share 
                                                                            and per share data)
<S>                                                             <C>                     <C>
Long-term portion of capital lease obligations...............       $    501               $     501
Mandatorily Redeemable Series A Preferred Stock,
$0.001 par value; no shares authorized; 100,000
shares issued and outstanding; aggregate
redemption and liquidation value of $1,000
plus cumulative dividends....................................          1,916                   1,916
Stockholders' equity (deficit):
     Preferred Stock, $0.001 par value,
        5,000,000 shares authorized;
        no shares issued and outstanding,
        actual and as adjusted...............................              -                       -
     Common Stock, $0.001 par value,
        20,000,000 shares authorized; 10,480,881
        shares issued and outstanding, as of
        June 30, 1997; 13,081,880 shares
        issued and outstanding, as adjusted(1)...............             10                      13
Additional paid-in capital...................................         46,271                  56,493
Deferred compensation........................................           (306)                   (306)
Deficit accumulated during development stage.................        (44,865)                (44,865)
                                                                     -------                --------
      Total stockholders' equity (deficit)...................          1,110                  11,335
                                                                     =======               =========
          Total capitalization................................       $(3,527)              $  13,752
                                                                     =======               =========
</TABLE>
- --------------------------------------
(1)  Includes 2,600,999 shares to be issued pursuant to the Purchase Agreement.
     Excludes (i) 2,940,992 shares reserved for issuance pursuant to the
     Company's stock option plans and (ii) 300,000 shares reserved for issuance
     pursuant to the Company's Employee Stock Purchase Plan.


                             SELLING STOCKHOLDERS

        The Shares covered by this Prospectus were acquired from the Company
pursuant to the Purchase Agreement for an aggregate purchase price of
$11,054,245 ($4.25 per share). The offer and sale by the Company of the Common
Stock to the Selling Stockholders pursuant to the Purchase Agreement was made
pursuant to an exemption from the registration requirements of the Securities
Act provided in Section 4(2) thereof. The Purchase Agreement contains
representations and warranties as to each Selling Stockholder's status as an
"accredited investor" as such term is defined in Rule 501 promulgated under the
Securities Act. Pacific Growth Equities, Inc., the placement agent, was paid a
fee equal to 7.0% of the aggregate purchase price in connection with the sale of
the Shares by the Company to the Selling Stockholders pursuant to the Purchase
Agreement. In addition, the Company agreed to reimburse such placement agent for
its reasonable out-of-pocket expenses incurred in connection with the sale of
the Shares by the Company to the Selling Stockholders, including the reasonable
fees and expenses of PGE's counsel, up to a maximum of $50,000.

        Pursuant to the Purchase Agreement, each Selling Stockholder has
represented that it acquired the Shares for investment and with no present
intention of distributing the Shares. The Company agreed, in such Purchase
Agreement, to prepare and file a registration statement as soon as practicable
and to bear all expenses other than fees and expenses of counsel 

                                       7
<PAGE>
 
 
for the Selling Stockholders and underwriting discounts and commissions and
brokerage commissions and fees. In addition, and in recognition of the fact that
the Selling Stockholders, even though purchasing the Shares without a view to
distribution, may wish to be legally permitted to sell the Shares when each
deems appropriate, the Company filed with the Commission a Registration
Statement on Form S-3, of which this Prospectus forms a part, with respect to,
among other things, the resale of the Shares from time to time at prevailing
prices in the over-the-counter market or in privately-negotiated transactions
and has agreed to prepare and file such amendments and supplements to the
Registration Statement as may be necessary to keep the Registration Statement
effective until the earliest of (A) the second anniversary date of the Closing,
(B) such date as all of the Shares have been resold or (C) such time as all of
the Shares held by the Purchasers can be sold within a given three-month period
pursuant to Rule 144 under the Securities Act.

        None of the Selling Stockholders has had a material relationship with
the Company within the past three years except as a result of the ownership of
the Shares or other securities of the Company and as set forth in the notes to
the following table.

        The following table sets forth the name of the Selling Stockholders, the
number of shares of Common Stock owned beneficially by the Selling Stockholders
as of October 17, 1997 (as adjusted to give effect to the purchases under
the Purchase Agreement) and the number of shares that may be offered pursuant to
this Prospectus. This information is based upon information provided by the
Selling Stockholders. There are currently no agreements, arrangements or
understandings with respect to the sale of any of the Shares. The Shares are
being registered to permit public secondary trading of the Shares, and the
Selling Stockholders may offer the Shares for resale from time to time.

<TABLE> 
<CAPTION>
                                                                                     Common                                       
                                                      Common Stock                    Stock                   Common Stock      
                                                   Beneficially Owned                 to be                Beneficially Owned 
                                                  Prior to Offering(1)                Sold                  After Offering(1)
                                                  -------------------              ----------               ---------------  
Holder                                        Number            Percent                              Number          Percent
- ------                                        ------            -------                              ------          -------     
<S>                                      <C>                                   <C>                <C>               <C>
Special Situations Fund III L.P.             400,000              3.0              400,000                --             -- 
                                                                                                                                  
Special Situations Cayman Fund L.P.          130,000              *                130,000                --             -- 
                                                                                                                                  
Special Situations Private Equity Fund  L.P. 176,000              1.3              176,000                --             --

WEC Partners, L.P.                            15,000              *                 15,000                --             --

East Peak Partners, LP                        50,000              *                 50,000                --             --

Bedford Enterprises, Inc.                      4,000              *                  3,000             1,000             *
                                                                                                      
Fidelity National Title Insurance            142,500              1.1               50,000            92,500             *
Company of New York                               
 
Lancaster Investment Partners, LP            100,000              *                100,000                --             --

Prism Partners I                             200,000              1.5              200,000                --             --

Viviana Partners, L.P.                        27,000              *                  7,000            20,000             *

Clarion Partners, LLP                         40,000              *                 40,000                --             --

Barrant V. Merrill                             5,000              *                  5,000                --             --

Allegro Partners, L.P.                        31,000              *                 25,000             6,000             *

Curran Partners L.P.                          25,000              *                 25,000                --             --

JTH Associates, Partnership                   25,000              *                 25,000                --             --

Veritas SG Investment Trust GmbH             100,000              *                100,000                --             --

Gary Rosenbach                                75,000              *                 75,000                --             --

Sonz Partners, L.P.                           30,000              *                 30,000                --             --

Bulldog Capital Partners L.P.                200,000              1.5              200,000                --             --

Porter Partners, LP                          100,000              *                100,000                --             --

Atlas II, L.P.                               117,000              *                 42,000            75,000             *

RJ Capital, L.P.                              79,706              *                 31,706            48,000             *

Gershon A. Stern                               5,000              *                  5,000                --             --

Teton Partners                               100,000              *                100,000                --             --

Trellus Management Co., LLC                   50,000              *                 50,000                --             --

Quantum Industrial Partners, LDC              50,000              *                 50,000                --             --

Winston Partners II, LLC                      50,000              *                 50,000                --             --

H&Q Life Sciences Investors                  332,417              2.5               94,117           238,300            1.8

H&Q Healthcare Investors                     501,476              3.8              141,176           360,400            2.7 

Brooks Industries of LI Profit Sharing        40,000              *                 40,000                --             --
Plan                                               
 
Anthony Kamin                                 10,000              *                 10,000                --             --

Gary W. Ross                                  50,000              *                 50,000                --             --

Schweizerische Treundhandgesellschat          25,000              *                 25,000                --             --

Pacific Growth Equities 401(k) Profit          2,000              *                  2,000                --             --
Sharing Plan FBO Stephen P. Schatz(2)
 
Pacific Growth Equities 401(k) Profit          4,000              *                  4,000                --             --
Sharing Plan FBO Thomas John Dietz(2)               
 
John Murray and Coralie Eddy Murray Trustees,
U/A/D 5-9-94 as amended, creating the 
Murray Family Trust(2)                        20,000              *                 20,000                --             --

Richard H. Osgood(2)                          20,000              *                 20,000                --             --

C. Fred Toney(2)                              23,000              *                 20,000             3,000             *

Robert Katz(2)                                 5,000              *                  5,000                --             --

Thomas J. Kumbatovic(2)                       10,000              *                 10,000                --             --

Thomas J. Levine(2)                           15,000              *                 15,000                --             --

Stephen J. Massocca(2)                        50,000              *                 50,000                --             --

John C. Coleman, Jr.(2)                       10,000              *                 10,000                --             --

TOTALS                                     3,445,199             26.1            2,600,999           844,200            6.4

</TABLE>
- -----------------------------
*    Less than 1%
(1)  Applicable percentage of ownership is based on 10,577,425 shares of Common
     Stock outstanding as of October 15, 1997, and assumes the sale and issuance
     of 2,600,999 shares of Common Stock pursuant to the Purchase Agreement.
(2)  Stockholder is affiliated with Pacific Growth Equities, Inc., the
     underwriter for the Company's initial public offering and the placement
     agent for the sale of the Shares to the Selling Stockholders.

                             PLAN OF DISTRIBUTION

        All or a portion of the Shares offered hereby by the Selling
Stockholders may be delivered and/or sold in transactions from time to time on
the over-the-counter market, on the Nasdaq SmallCap Market, in negotiated
transactions, or by a combination of such methods of sale, at market prices
prevailing at the time, at prices related to such prevailing prices or at
negotiated prices and/or may also be used to cover any short positions
previously established. The Selling Stockholders may effect such transactions by
selling to or through one or more broker-dealers, and such broker-dealers may
receive compensation 

                                       8
<PAGE>
 
in the form of underwriting discounts, concessions or commissions from the
Selling Stockholders. The Selling Stockholders and any broker-dealers that
participate in the distribution may under certain circumstances be deemed to be
"underwriters" within the meaning of the Securities Act, and any commissions
received by such broker-dealers and any profits realized on the resale of Shares
by them may be deemed to be underwriting discounts and commissions under the
Securities Act. The Selling Stockholders may agree to indemnify such broker-
dealers against certain liabilities, including liabilities under the Securities
Act. In addition, the Company has agreed to indemnify the Selling Stockholders
with respect to the Shares offered hereby against certain liabilities,
including, without limitation, certain liabilities under the Securities Act, or,
if such indemnity is unavailable, to contribute toward amounts required to be
paid in respect of such liabilities.

        Any broker-dealer participating in such transactions as agent may
receive commissions from the Selling Stockholders (and, if they act as agent for
the purchaser of such Shares, from such purchaser). Broker-dealers may agree
with the Selling Stockholders to sell a specified number of Shares at a
stipulated price per share, and, to the extent such a broker-dealer is unable to
do so acting as agent for the Selling Stockholders, to purchase as principal any
unsold Shares at the price required to fulfill the broker-dealer commitment to
the Selling Stockholders. Broker-dealers who acquire Shares as principal may
thereafter resell such Shares from time to time in transactions (which may
involve crosses and block transactions and which may involve sales to and
through other broker-dealers, including transactions of the nature described
above) in the over-the-counter market, in negotiated transactions or otherwise
at market prices prevailing at the time of sale or at negotiated prices, and in
connection with such resales may pay to or receive from the purchasers of such
Shares commissions computed as described above. To the extent required under the
Securities Act, a supplemental prospectus will be filed, disclosing (a) the name
of any such broker-dealers, (b) the number of Shares involved, (c) the price at
which such Shares are to be sold, (d) the commissions paid or discounts or
concessions allowed to such broker-dealers, where applicable, (e) that such
broker-dealers did not conduct any investigation to verify the information set
out or incorporated by reference in this prospectus, as supplemented, and (f)
other facts material to the transaction.

        Under applicable rules and regulations under the Exchange Act, any
person engaged in the distribution or the resale of Shares may not
simultaneously engage in market making activities with respect to the Common
Stock of the Company for a period of two business days prior to the commencement
of such distribution. In addition and without limiting the foregoing, the
Selling Stockholders will be subject to applicable provisions of the Exchange
Act, and the rules and regulations thereunder, including, without limitation,
Rules 10b-6 and 10b-7, which provisions may limit the timing of purchases and
sales of shares of the Company's Common Stock by the Selling Stockholders.

        The Selling Stockholders will pay all commissions, transfer taxes, and
other expenses associated with the sale of securities by them. The Shares
offered hereby are being registered pursuant to contractual obligations of the
Company, and the Company has paid the expenses of the preparation of this
Prospectus. The Company has not made any underwriting arrangements with respect
to the sale of Shares offered hereby.

                                USE OF PROCEEDS

        The Company will not receive any of the proceeds from the sale of the
shares by the Selling Stockholders.

                                 LEGAL MATTERS

        The validity of the securities offered hereby will be passed upon for
the Company by Heller Ehrman White & McAuliffe, Palo Alto, California, counsel
to the Company in connection with the offering.

                                    EXPERTS

        The financial statements of Calypte Biomedical Corporation as of
December 31, 1996 and 1995, and for each of the years in the three-year period
ended December 31, 1996 and for the period from February 18, 1988 (inception)
through December 31, 1996, have been incorporated by reference herein and in the
Registration Statement in reliance upon the report of KPMG Peat Marwick LLP,
independent auditors, incorporated by reference herein, and upon the authority
of said firm as experts in accounting and auditing.

                                       9
<PAGE>
 
                                    PART II

                    INFORMATION NOT REQUIRED IN PROSPECTUS

ITEM 14.  OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION.

        The following table sets forth the various expenses in connection with
the sale and distribution of the securities being registered. All of the amounts
shown are estimates except the Securities and Exchange Commission registration
fee.

<TABLE>
<CAPTION>
<S>                                                                     <C>
Securities and Exchange Commission
        Registration Fee.............................................   $ 3,989
Legal fees and expenses..............................................    30,000
Accounting fees and expenses.........................................     5,000
Miscellaneous........................................................     6,011
                                                                        --------
Total................................................................   $45,000
                                                                        ========
</TABLE>

ITEM 15.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

        Section 145 of the Delaware General Corporation Law permits a
corporation to include in its charter documents, and in agreements between the
corporation and its directors and officers, provisions expanding the scope of
indemnification beyond that specifically provided by the current law.
 
        Article VIII of the Registrant's Certificate of Incorporation provides
for the indemnification of directors to the fullest extent permissible under
Delaware law.
 
        Article VI of the Registrant's Bylaws provides for the indemnification
of officers, directors and third parties acting on behalf of the corporation if
such person acted in good faith and in a manner reasonably believed to be in and
not opposed to the best interest of the corporation, and, with respect to any
criminal action or proceeding, the indemnified party had no reason to believe
his conduct was unlawful.

        The Registrant has entered into indemnification agreements with its
directors and executive officers, in addition to indemnification provided for in
the Registrant's Bylaws, and intends to enter into indemnification agreements
with any new directors and executive officers in the future.

ITEM 16.  EXHIBITS
- -------   --------

Exhibit         Description
- -------         -----------
   4.1          Common Stock Purchase Agreement between Registrant and the
                Selling Stockholders, dated October 17, 1997

   5.1          Opinion of Heller Ehrman White & McAuliffe

  23.1          Consent of Heller Ehrman White & McAuliffe
                (filed as part of Exhibit 5.1)

  23.2          Consent of KPMG Peat Marwick LLP, Independent Auditors

  24.1          Power of Attorney (see pages II-3 and  II-4)


                                     II-1
<PAGE>
 
ITEM 17.  UNDERTAKINGS

        A.  The undersigned registrant hereby undertakes:

            (1)  To file, during any period in which offers or sales are being
made, a post-effective amendment to this registration statement;

                (i)   To include any prospectus required by Section 10(a)(3) of
     the Securities Act of 1933;

                (ii)  To reflect in the prospectus any facts or events arising
     after the effective date of the registration statement (or the most recent
     post-effective amendment thereof) which, individually or in the aggregate,
     represent a fundamental change in the information set forth in the
     registration statement;

                (iii) To include any material information with respect to the
     plan of distribution not previously disclosed in the registration statement
     or any material change to such information in the registration statement;

provided, however, that paragraphs A(1)(i) and A(1)(ii) do not apply if the
information required to be included in a post-effective amendment by those
paragraphs is contained in periodic reports filed by the registrant pursuant to
Section 13 or 15(d) of the Securities Exchange Act of 1934 that are incorporated
by reference in the registration statement.

            (2)  That, for the purpose of determining any liability under the
Securities Act of 1933, each such post-effective amendment shall be deemed to be
a new registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

            (3)  To remove from registration by means of a post-effective
amendment any of the securities being registered which remain unsold at the
termination of the offering.

        B.  The undersigned registrant hereby undertakes that, for purposes of
determining liability under the Securities Act of 1933, each filing of the
registrant's annual report pursuant to Section 13(a) or 15(d) of the Securities
Exchange Act of 1934 that is incorporated by reference in the registration
statement shall be deemed a new registration statement relating to the
securities offered therein, and the offering of such securities at that time
shall be deemed to be the initial bona fide offering thereof.

        C.  Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the registrant pursuant to the foregoing provisions, or otherwise,
the registrant has been advised that in the opinion of the Securities and
Exchange Commission such indemnification is against public policy as expressed
in the Act and is, therefore, unenforceable. In the event that a claim for
indemnification against such liabilities (other than the payment by the
registrant of expenses incurred or paid by a director, officer or controlling
person of the registrant in the successful defense of any action, suit or
proceeding) is asserted by such director, officer or controlling person in
connection with the securities being registered, the registrant will, unless in
the opinion of its counsel the matter has been settled by controlling precedent,
submit to a court of appropriate jurisdiction the question whether such
indemnification by it is against public policy as expressed in the Act and will
be governed by the final adjudication of such issue.


                                     II-2
<PAGE>
 
                                  SIGNATURES

        Pursuant to the requirements of the Securities Act of 1933, the
Registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form S-3 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the city of Berkeley, State of California, on October 21, 1997.

                                
                                                CALYPTE BIOMEDICAL CORPORATION

                                                 /s/ John P. Davis
                                                --------------------------------
                                                John P. Davis
                                                President and Chief Executive 
                                                Officer

                               POWER OF ATTORNEY

        Each person whose signature appears below constitutes and appoints John
P. Davis and John J. DiPietro his true and lawful attorneys-in-fact and agents,
each acting alone, with full power of substitution and resubstitution, for him
and in his name, place and stead, in any and all capacities, to sign any or all
amendments (including post-effective amendments) to the Registration Statement,
and to sign any registration statement for the same offering covered by this
Registration Statement that is to be effective upon filing pursuant to Rule
462(b) under the Securities Act of 1933, as amended, and all post-effective
amendments thereto, and to file the same, with all exhibits thereto, and all
documents in connection therewith, with the Securities and Exchange Commission,
granting unto said attorneys-in-fact and agents, full power and authority to do
and perform each and every act and thing requisite and necessary to be done in
and about the premises, as fully to all intents and purposes as he might or
could do in person, hereby ratifying and confirming all that said attorneys-in-
fact and agents, each acting alone, or his or her substitute or substitutes, may
lawfully do or cause to be done by virtue hereof.

        Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities and on the dates indicated:

<TABLE> 
<CAPTION> 
SIGNATURE                       TITLE                                   DATE
- ---------                       -----                                   ----
<S>                             <C>                                     <C> 

 /s/ William A. Boeger, III
- ----------------------------    Chairman of Board of Directors          October 21, 1997 
William A. Boeger, III                                                         

 /s/ John P. Davis
- ----------------------------    President, Chief Executive Officer      October 21, 1997 
John P. Davis                   and Director                                   
                                (Principal Executive Officer)   


 /s/ Howard B. Urnovitz
- -----------------------------   Chief Science Officer and Director      October 21, 1997 
Howard B. Urnovitz, Ph.D.                                                      

 /s/ John J. DiPierto
- -----------------------------   Vice President of Finance,              October 21, 1997 
John J. DiPietro                Chief Financial Officer and Secretary          
                                (Principal Financial and Accounting 
                                Officer) 

 /s/ David Collins
- -----------------------------   Director                                October 21, 1997 
David Collins                                                                  

 /s/ Julius R. Krevans
- -----------------------------   Director                                October 21, 1997 
Julius R. Krevans, M.D.                                                        

 /s/ Mark Novitch
- -----------------------------   Director                                October 21, 1997 
Mark Novitch, M.D.                                                             

 /s/ Zafar I. Randawa
- -----------------------------   Director                                October 21, 1997 
Zafar I. Randawa, Ph.D.                                                        
</TABLE> 

                                     II-3

<PAGE>
 
                        CALYPTE BIOMEDICAL CORPORATION

                               Index to Exhibits
                               -----------------

<TABLE> 
<CAPTION> 

Exhibit No.                             Description    
- -----------     ------------------------------------------------------------------------
<S>             <C> 
4.1             Common Stock Purchase Agreement between Registrant and, the Selling
                Stockholders, dated October 17, 1997

5.1             Opinion of Heller, Ehrman, White & McAuliffe  

23.1            Consent of Heller, Ehrman, White & McAuliffe (filed as part of Exhibit 5.1)   

23.2            Consent of KPMG Peat Marwick LLP, Independent Auditors  

24.1            Power of Attorney (See Page II-3)

</TABLE> 

<PAGE>

                                                                     EXHIBIT 4.1
 
                       CALYPTE BIOMEDICAL CORPORATION


                                COMMON STOCK

                             PURCHASE AGREEMENT


                              OCTOBER 17, 1997
<PAGE>
 
NOTICE TO PURCHASERS IN ALL STATES:



IN MAKING AN INVESTMENT DECISION INVESTORS MUST RELY ON THEIR OWN EXAMINATION OF
THE ISSUER AND THE TERMS OF THE OFFERING, INCLUDING THE MERITS AND RISKS
INVOLVED.  THESE SECURITIES HAVE NOT BEEN RECOMMENDED BY ANY FEDERAL OR STATE
SECURITIES COMMISSION OR REGULATORY AUTHORITY.  FURTHERMORE, THE FOREGOING
AUTHORITIES HAVE NOT CONFIRMED THE ACCURACY OR DETERMINED THE ADEQUACY OF THIS
DOCUMENT.  ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND RESALE AND
MAY NOT BE TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE SECURITIES ACT OF
1933, AS AMENDED, AND THE APPLICABLE STATE SECURITIES LAWS, PURSUANT TO
REGISTRATION OR EXEMPTION THEREFROM.  INVESTORS SHOULD BE AWARE THAT THEY WILL
BE REQUIRED TO BEAR THE FINANCIAL RISKS OF THIS INVESTMENT FOR AN INDEFINITE
PERIOD OF TIME.

<PAGE>
 

                                COMMON STOCK
                             PURCHASE AGREEMENT

     This Agreement ("Agreement") is made as of October 17, 1997 (the "Effective
Date"), by and among Calypte Biomedical Corporation, a Delaware corporation (the
"Company"), and each of those persons and entities, severally and not jointly,
listed as a Purchaser on the Schedule of Purchasers attached as Exhibit A
hereto.  Such persons and entities are hereinafter collectively referred to
herein as "Purchasers" and each individually as a "Purchaser."

                                  AGREEMENT

     In consideration of the mutual covenants contained in this Agreement, and
for other good and valuable consideration, the receipt of which is hereby
acknowledged, the Company and each Purchaser (severally and not jointly) hereby
agree as follows:


     SECTION 1.    AUTHORIZATION OF SALE OF THE SECURITIES.  Subject to the
terms and conditions of this Agreement, the Company has, or before the Closing
(as defined below) will have, authorized the sale and issuance of up to
3,000,000 shares of its Common Stock (the "Common Stock").  The shares of Common
Stock sold hereunder shall be referred to herein as the "Shares" or the
"Securities."

     SECTION 2.    AGREEMENT TO SELL AND PURCHASE THE SECURITIES.


     2.1 SALE OF SHARES.  At the Closing (as defined in Section 3), the
Company will sell to each Purchaser, and each Purchaser will purchase from the
Company, at a purchase price of four dollars and twenty-five cents ($4.25) per
Share, the number of Shares set forth next to such Purchaser's name on the
Schedule of Purchasers attached hereto as Exhibit A (the "Schedule of
Purchasers").

     2.2 SEPARATE AGREEMENT.  Each Purchaser shall severally, and not jointly,
be liable for only the purchase of the Shares that appear on Exhibit A hereto
and that relate to such Purchaser. The Company's agreement with each of the
Purchasers is a separate agreement, and the sale of Shares to each of the
Purchasers is a separate sale. The obligations of each Purchaser hereunder are
expressly not conditioned on the purchase by any or all of the other
Purchasers of the Shares such other Purchasers have agreed to purchase.
<PAGE>
 
     SECTION 3.    CLOSING AND DELIVERY.


     3.1 CLOSING.  The Closing of the purchase and sale of the Shares pursuant
to this Agreement (the "Closing") shall be held as soon as practicable after
the filing of the Registration Statement, as set forth in Section 9.1(a)
hereof, with the Securities and Exchange Commission (the "SEC" or the
"Commission"), and satisfaction or waiver of all other conditions to Closing
set forth in Sections 7 and 8 hereof, at the offices of Heller Ehrman White &
McAuliffe, 525 University Avenue, Palo Alto, California 94301, or on such
other date and place as may be agreed to by the Company and the Purchasers.

     The Company shall give at least one (1) business day prior written notice
to the Purchasers, in a manner provided for in Section 11 hereof, of the date,
time and location of the Closing.  At or prior to the Closing, each Purchaser
shall execute any related agreements or other documents required to be executed
hereunder, dated as of the date of the Closing (the "Closing Date").

     3.2 DELIVERY OF THE SHARES AT THE CLOSING.  At the Closing, the Company
shall deliver to each Purchaser stock certificates registered in the name of
such Purchaser, or in such nominee name(s) as designated by such Purchaser,
representing the number of shares of Common Stock to be purchased by such
Purchaser at the Closing as set forth in the Schedule of Purchasers against
payment of the purchase price for such shares. The name(s) in which the stock
certificates are to be issued to each Purchaser are set forth in the Stock
Certificate Questionnaire in the form attached hereto as Appendix I, as
completed by each Purchaser.



     SECTION 4.    REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE COMPANY.

     Except as set forth on the Schedule of Exceptions attached hereto as
Exhibit B, the Company hereby represents and warrants as of the date hereof to,
and covenants with, the Purchasers as follows:

     4.1 ORGANIZATION AND STANDING.  The Company has been duly incorporated
and is validly existing as a corporation in good standing under the laws of
Delaware, has full corporate power and authority to own or lease its
properties and conduct its business as presently conducted, and is duly
qualified as a foreign corporation and in good standing in all jurisdictions
in which the character of the property owned or leased or the nature of the
business transacted by it makes qualification necessary (except where the
failure to be so qualified would not have a material adverse effect on the
business, properties, financial condition or results or operations of the
Company). The Company has no subsidiaries or equity interest in any other
entity.

                                       2
<PAGE>
 
     4.2 CORPORATE POWER; AUTHORIZATION.  The Company has all requisite
corporate power, and has taken all requisite corporate action, to execute and
deliver this Agreement, sell and issue the Shares and carry out and perform
all of its obligations under this Agreement. This Agreement constitutes the
legal, valid and binding obligation of the Company, enforceable in accordance
with its terms, except (i) as limited by applicable bankruptcy, insolvency,
reorganization, moratorium or similar laws relating to or affecting the
enforcement of creditors' rights generally, (ii) as limited by equitable
principles generally, including any specific performance, and (iii) as to
those provisions of Section 9.3 relating to indemnity or contribution. The
execution and delivery of this Agreement does not, and the performance of this
Agreement and the compliance with the provisions hereof and the issuance, sale
and delivery of the Shares by the Company will not conflict with, or result in
a breach or violation of the terms, conditions or provisions of, or constitute
a default under, or result in the creation or imposition of any lien pursuant
to the terms of, the Certificate of Incorporation or Bylaws of the Company or
any statute, law, rule applicable to the Company or regulation or any state or
federal order, judgment or decree applicable to the Company or any indenture,
mortgage, lease or other agreement or instrument to which the Company or any
of its properties is subject, where such conflict, breach or violation would
have a material adverse effect on the Company.

     4.3 ISSUANCE AND DELIVERY OF THE SHARES.  The Shares, when issued and
paid for in compliance with the provisions of this Agreement, will be validly
issued, fully paid and nonassessable. The issuance and delivery of the Shares
is not subject to preemptive, co-sale, right of first refusal or any other
similar rights of the stockholders of the Company or any liens or
encumbrances.

     4.4 SEC DOCUMENTS; FINANCIAL STATEMENTS.  The Company has filed in a timely
manner all documents that the Company was required to file with the SEC under
Sections 13, 14(a) and 15(d) of the Securities Exchange Act of 1934, as amended
(the "Exchange Act"), during the twelve (12) months preceding the date of this
Agreement.  As of their respective filing dates (or, if amended prior to the
date of this Agreement, when amended), all documents filed by the Company with
the SEC (the "SEC Documents") complied in all material respects with the
requirements of the Exchange Act.  None of the SEC Documents as of their
respective dates contained any untrue statement of material fact or omitted to
state a material fact required to be stated therein or necessary to make the
statements made therein, in light of the circumstances under which they were
made, not misleading.  The financial statements of the Company included in the
SEC Documents (the "Financial Statements") comply as to form in all material
respects with applicable accounting requirements and with the published rules
and regulations of the SEC with respect thereto.  The Financial Statements have
been prepared in accordance with generally accepted accounting principles
consistently applied and fairly present the financial position of the Company at
the dates thereof and the results of its operations and 

                                       3
<PAGE>
 
cash flows for the periods then ended (subject, in the case of unaudited
statements, to normal, recurring adjustments).

     4.5 INTELLECTUAL PROPERTY.  The Company owns or possesses adequate rights
to use all material patents, patent rights, inventions, trade secrets and know-
how described or referred to in the SEC Documents as owned or used by it or
that are necessary for the conduct of its business as presently conducted and
as described in the SEC Documents. Except as set forth in the SEC Documents,
the Company has not received any notice of, nor has any knowledge of, any
infringement of or conflict with asserted rights of others with respect to any
patent, patent right, invention, trade secret or know-how that, individually
or in the aggregate, if the subject of an unfavorable decision, ruling or
finding, would have a material adverse effect on the business, properties,
financial condition or results or operations of the Company.

     4.6 CAPITALIZATION.  All of the Company's outstanding shares of capital
stock have been duly authorized and validly issued and are fully paid and
nonassessable, have been issued in compliance with all federal and state
securities laws, and were not issued in violation of or subject to any
preemptive right or other rights to subscribe for or purchase securities. The
actual authorized and outstanding capital stock of the Company as of the date
hereof is as set forth in Section 4.6 of Exhibit B. Except as set forth in
Exhibit B, there are no outstanding options to purchase, or any preemptive
rights or other rights to subscribe for or to purchase, any securities or
obligations convertible into, or any contracts or commitments to issue or sell
shares of the company's capital stock or any such options, rights, convertible
securities or obligations.

     4.7 LITIGATION.   There is no pending or, to the Company's knowledge,
threatened, action, suit or other proceeding to which the Company is a party or
to which its property or assets are subject.

     4.8 GOVERNMENTAL CONSENTS.  No consent, approval, order or authorization
of, or registration, qualification, designation, declaration or filing with,
any federal, state, or local governmental authority on the part of the Company
is required in connection with the consummation of the transactions
contemplated by this Agreement except for (a) compliance with the securities
and blue sky laws in the states and other jurisdictions in which shares of
Common Stock are offered and/or sold, which compliance will be effected in
accordance with such laws, and (b) the filing of a registration statement and
all amendments thereto with the SEC as contemplated by Section 9.1 of this
Agreement.

     4.9 NO MATERIAL ADVERSE CHANGE.  Since June 30, 1997, there have not been
any changes in the assets, liabilities, financial condition or operations of
the Company from that reflected in the Financial Statements except changes
which have not been, either individually or in the aggregate, materially
adverse.

                                       4
<PAGE>
 
     4.10 LISTING; MAINTENANCE OF LISTING.  The Company's Common Stock is
traded on the Nasdaq SmallCap Market. For so long as the Company is obligated
to keep in effect the Registration Statement provided for in Section 9 hereof,
the Company will use its reasonable best efforts to maintain its listing on
the Nasdaq SmallCap Market, the Nasdaq National Market or a national
securities exchange, as defined in the Exchange Act.


     SECTION 5.    REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE
                   PURCHASERS.

      5.1  Each Purchaser, severally and not jointly, represents and warrants
to and covenants with the Company that:

      (a) Purchaser, taking into account the personnel and resources it can
practically bring to bear on the purchase of the Securities contemplated hereby,
either alone or together with the advice of such Purchaser's purchaser
representative, is knowledgeable, sophisticated and experienced in making, and
is qualified to make, decisions with respect to investments in shares presenting
an investment decision like that involved in the purchase of the Securities,
including investments in securities issued by the Company, and has requested,
received, reviewed and considered, either alone or with such Purchaser's
purchaser representative, all information Purchaser deems relevant (including
the SEC documents) in making an informed decision to purchase the Securities.

      (b) Purchaser is acquiring the Securities being acquired by Purchaser
pursuant to this Agreement in the ordinary course of its business and for its
own account for investment only and with no present intention of distributing
any of such Securities or any arrangement or understanding with any other
persons regarding the distribution of such Securities, except in compliance with
Section 5.1(c).

      (c) Purchaser will not, directly or indirectly, offer, sell, pledge,
transfer or otherwise dispose of (or solicit any offers to buy, purchase or
otherwise acquire or take a pledge of) any of the securities purchased hereunder
except in compliance with the Securities Act of 1933, as amended (the
"Securities Act"), applicable blue sky laws, and the rules and regulations
promulgated thereunder.

      (d) Purchaser has completed or caused to be completed the Stock
Certificate Questionnaire and the Registration Questionnaire, attached hereto as
Appendix I and Appendix II, respectively, for use in preparation of the
Registration Statement to be filed by the Company, and the answers thereto are
true and correct as of the date hereof and will be true and correct as of the
effective date of the applicable Registration Statement (provided that Purchaser
shall be entitled to update such information by providing notice thereof to the
Company prior to the effective date of such Registration Statement).

                                       5
<PAGE>
 
      (e) Purchaser has, in connection with its decision to purchase the
Securities, relied with respect to the Company and its affairs solely upon the
SEC Document, the representations and warranties of the Company contained
herein and oral statements made by management of the Company at meetings with 
Purchaser.

      (f) Purchaser is an "accredited investor" within the meaning of Rule 501
of Regulation D promulgated under the Securities Act or a Qualified
Institutional Buyer within the meaning of Rule 144A promulgated under the
Securities Act.

      (g) Purchaser has full right, power, authority and capacity to enter into
this Agreement and to consummate the transactions contemplated hereby and has
taken all necessary action to authorize the execution, delivery and performance
of this Agreement.  Upon the execution and delivery of this Agreement by
Purchaser, this Agreement shall constitute a valid and binding obligation of
Purchaser, enforceable in accordance with its terms, except (i) as limited by
applicable bankruptcy, insolvency, reorganization, moratorium or similar laws
relating to or affecting the enforcement of creditors' rights generally, (ii) as
limited by equitable principles generally, including any specific performance,
and (iii) as to those provisions of Section 9.3 relating to indemnity or
contribution.

 5.2 Purchaser represents and warrants to and covenants with the Company that
Purchaser has not engaged and will not engage in any short sales of the
Company's Common Stock prior to the effectiveness of the Registration Statement,
except to the extent that any such short sale is fully covered by shares of
Common Stock of the Company other than the Shares.

 5.3 Purchaser understands that nothing in this Agreement or any other materials
presented to Purchaser in connection with the purchase and sale of the Shares
constitutes legal, tax or investment advice and that no independent legal
counsel has reviewed these documents and materials on Purchaser's behalf.
Purchaser has consulted such legal, tax and investment advisors as it, in its
sole discretion, has deemed necessary or appropriate in connection with its
purchase of the Shares.



     SECTION 6.    SURVIVAL OF REPRESENTATIONS, WARRANTIES AND AGREEMENTS.

     Notwithstanding any investigation made by any party to this Agreement, all
covenants, agreements, representations and warranties made by the Company and
each Purchaser herein and in the certificates for the securities delivered
pursuant hereto shall survive the execution of this Agreement, the delivery to
the Purchasers of the securities being purchased and the payment therefor.

                                       6
<PAGE>
 
     SECTION 7.    CONDITIONS TO COMPANY'S OBLIGATIONS AT THE CLOSING.

     The Company's obligation to complete the sale and issuance of the
Securities and deliver shares of Common Stock to each Purchaser, individually,
as set forth in the Schedule of Purchasers shall be subject to the following
conditions to the extent not waived by the Company:

     7.1 RECEIPT OF PAYMENT.  The Company shall have received payment, by
check or wire transfer of immediately available funds, in the full amount of
the purchase price for the number of Shares being purchased by such Purchaser
at the Closing as set forth in the Schedule of Purchasers.

     7.2 REGISTRATION STATEMENT FILED.  The Registration Statement shall have
been filed by the Company pursuant to Section 9 with the Securities and
Exchange Commission.

     7.3 REPRESENTATIONS AND WARRANTIES CORRECT.  The representations and
warranties made by such Purchaser in Section 5 hereof shall be true and
correct when made, and shall be true and correct on the Closing Date.



     SECTION 8.    CONDITIONS TO PURCHASERS' OBLIGATIONS AT THE CLOSING.

     Each Purchaser's obligation to accept delivery of the Shares and to pay for
the Shares shall be subject to the following conditions to the extent not waived
by such Purchaser:

     8.1 REGISTRATION STATEMENT FILED.  The Registration Statement required
pursuant to Section 9 shall have been filed with the Commission.

     8.2 REPRESENTATIONS AND WARRANTIES CORRECT.  The representations and
warranties made by the Company in Section 4 hereof shall be true and correct
when made, and shall be true and correct on the Closing Date.

     8.3 LEGAL OPINION.  Purchasers shall have received from Heller Ehrman
White & McAuliffe, counsel to the Company, an opinion letter addressed to the
Purchasers, dated as of the Closing Date, covering the matters set forth in
Exhibit C hereto, subject to customary assumptions and qualifications.

     8.4 TERMINATION.  This Agreement may be terminated by any Purchaser with
respect to such Purchaser only if the Closing has not transpired by December 31,
1997.



     SECTION 9.    REGISTRATION OF THE SHARES; COMPLIANCE WITH THE 
                   SECURITIES ACT.

     9.1 REGISTRATION PROCEDURES AND EXPENSES.  The Company is obligated to do
the following:

                                       7
<PAGE>
 
      (a) As soon as practicable following the Effective Date and in any event
no later than ten (10) days following the Effective Date, the Company shall
prepare and file with the Commission one or more registration statements in
order to register with the Commission the resale by the Purchasers, from time to
time, of the Shares through Nasdaq or the facilities of any national securities
exchange on which the Company's Common Stock is then traded, or in privately-
negotiated transactions (a "Registration Statement"). The Company shall use
its best efforts to cause such Registration Statement to be declared effective
as soon thereafter as reasonably possible.

      (b) The Company shall prepare and file with the Commission (i) such
amendments and supplements to the Registration Statement and the prospectus used
in connection therewith, (ii) such SEC Reports and (iii) such other filings
required by the Commission, in each case as may be necessary to keep the
Registration Statement continuously effective and not misleading until the
earliest of (A) the second anniversary date of the Closing, (B) such date as all
of the Shares have been resold or (C) such time as all of the Shares held by the
Purchasers can be sold within a given three-month period pursuant to Rule 144
under the Securities Act.  Notwithstanding the foregoing, following the
effectiveness of the Registration Statement, the Company may, at any time,
suspend the effectiveness of the Registration Statement for up to no longer than
30 days, as appropriate (a "Suspension Period"), by giving notice to the
Purchasers, if the Company shall have determined that the Company may be
required to disclose any material corporate development.  The Company will use
its best efforts to minimize the length of any Suspension Period.
Notwithstanding the foregoing, the Company may not suspend the effectiveness of
the Registration Statement more than twice in any twelve (12) month period.
Each Purchaser agrees that, upon receipt of any notice from the Company of a
Suspension Period, such Purchaser will not sell any Shares pursuant to the
Registration Statement until (i) such Purchaser is advised in writing by the
Company that the use of the applicable prospectus may be resumed, (ii) such
Purchaser has received copies of any additional or supplemental or amended
prospectus, if applicable, and (iii) such Purchaser has received copies of any
additional or supplemental filings which are incorporated or deemed to be
incorporated by reference in such prospectus.

      (c) In order to facilitate the public sale or other disposition of all or
any of the shares by each Purchaser, the Company shall furnish to each Purchaser
with respect to the Shares registered under the Registration Statement such
number of copies of prospectuses, prospectus supplements and preliminary
prospectuses as such Purchaser reasonably requests in conformity with the
requirements of the Securities Act.

      (d) The Company shall file any documents required of the Company for
normal blue sky clearance in states specified in writing by each Purchaser;
provided, however, that the Company shall not be required to qualify to do
business or consent to service of process in any jurisdiction in which it is not
now so qualified or has not so consented.

                                       8
<PAGE>
 
      (e) Other than fees and expenses, if any, of counsel or other advisers to
the Purchasers, which fees and expenses shall be borne by the Purchasers, the
Company shall bear all expenses (exclusive of any brokerage fees, underwriting
discounts and commissions) in connection with the procedures in paragraphs (a)
through (d) of this Section 9.1.

      (f) With a view to making available to the Purchasers the benefits of Rule
144 promulgated under the Securities Act ("Rule 144") and any other rule or
regulation of the SEC that may at any time permit a Purchaser to sell Shares to
the public without registration or pursuant to registration, the Company
covenants and agrees to: (i) make and keep public information available, as
those terms are understood and defined in Rule 144, until the earlier of (A) the
second anniversary of the Closing Date or (B) such date as all of the Shares
shall have been resold; (ii) file with the SEC in a timely manner all reports
and other documents required of the Company under the Exchange Act; and (iii)
furnish to any Purchaser upon request, as long as the Purchaser owns any Shares,
(A) a written statement by the Company that it has complied with the reporting
requirements of the Exchange Act, (B) a copy of the most recent annual or
quarterly report of the Company, and (C) such other information as may be
reasonably requested in order to avail any Purchaser of any rule or regulation
of the SEC that permits the selling of any such Shares without registration
under the Securities Act.

 9.2 Transfer of Securities After Registration.  Each Purchaser agrees that such
Purchaser will not effect any disposition of the Shares that would constitute a
sale within the meaning of the Securities Act, except:

      (i) pursuant to the Registration Statement, in which case such Purchaser
shall submit the certificates evidencing the Shares to the Company's transfer
agent, accompanied by a separate "Purchaser's Certificate" (A) in the form of
Appendix III attached hereto, (B) executed by such Purchaser or by an officer
of, or other authorized person designated by, such Purchaser, and (C) to the
effect that (1) the Shares have been sold in accordance with the Registration
Statement and (2) the requirement of delivering a current prospectus has been
satisfied; or

     (ii) in a transaction exempt from registration under the Securities Act, in
which case such Purchaser shall, prior to effecting such disposition, submit to
the Company an opinion of counsel in form and substance reasonably satisfactory
to the Company to the effect that the proposed transaction is in compliance with
the Securities Act.

     9.3 INDEMNIFICATION.  As used in this Section 9.3 the following terms shall
have the following respective meanings:

                                       9
<PAGE>
 
      (a) "Selling Stockholder" shall mean a Purchaser of Securities under this
Agreement and any transferee of such a Purchaser who is entitled to resell
Shares pursuant to the Registration Statement;

      (b) "Registration Statement" shall include any final prospectus, exhibit,
supplement or amendment included in or relating to the Registration Statement
referred to in Section 9.1; and

      (c) "Untrue Statement" shall include any untrue statement or alleged
untrue statement, or any omission or alleged omission to state in the
Registration Statement a material fact required to be stated therein or
necessary to make the statements therein, in the light of the circumstances
under which they were made, not misleading.

     The Company agrees to indemnify and hold harmless each Selling Stockholder
from and against any losses, claims, damages or liabilities to which such
Selling Stockholder may become subject (under the Securities Act or otherwise)
insofar as such losses, claims, damages or liabilities (or actions or
proceedings in respect thereof) arise out of, or are based upon, any Untrue
Statement on or after the effective date of the Registration Statement, or on or
after the date of any prospectus or prospectus supplement or the date of any
sale by Purchaser thereunder, or arise out of any failure by the Company to
fulfill any undertaking included in the Registration Statement and the Company
will reimburse such Selling Stockholder for any reasonable legal or other
expenses reasonably incurred in investigating, defending or preparing to defend
any such action, proceeding or claim; provided, however, that the Company shall
not be liable to such Selling Stockholder in any such case to the extent that
such loss, claim, damage or liability arises out of, or is based upon, an Untrue
Statement made in such Registration Statement in reliance upon and in conformity
with written information furnished to the Company by or on behalf of such
Selling Stockholder specifically for use in preparation of the Registration
Statement, or the failure of such Selling Stockholder to comply with the
covenants and agreements contained in Section 9.1 or 9.2 hereof respecting sale
of the Shares or any statement or omission in any Prospectus that is corrected
in any subsequent prospectus that was delivered to the Selling Stockholder prior
to the pertinent sale or sales by the Selling Stockholder.

     Each Purchaser, severally and not jointly, agrees to indemnify and hold
harmless the Company (and each person, if any, who controls the Company within
the meaning of Section 15 of the Securities Act, each officer of the Company who
signs the Registration Statement and each director of the Company) from and
against any losses, claims, damages or liabilities to which the Company (or any
such officer, director or controlling person) may become subject (under the
Securities Act or otherwise), insofar as such losses, claims, damages or
liabilities (or actions or proceedings in respect thereof) arise out of, or are
based upon, any failure to comply with the covenants and agreements 

                                       10
<PAGE>
 
contained in Section 9.1 or 9.2 hereof respecting sale of the Shares, or any
Untrue Statement contained in the Registration Statement on or after the
effective date thereof, or in any prospectus supplement as of its issue date
or date of any sale by Purchaser thereunder, if such Untrue Statement was made
in reliance upon and in conformity with written information furnished by or on
behalf of such Purchaser specifically for use in preparation of the
Registration Statement, and such Purchaser will reimburse the Company (or such
officer, director or controlling person), as the case may be, for any legal or
other expenses reasonably incurred in investigating, defending or preparing to
defend any such action, proceeding or claim; provided that in no event shall any
indemnity by a Purchaser under this Section 9.3 exceed the gross proceeds
received by such Purchaser from the sale of Shares covered by such Registration
Statement.

     Promptly after receipt by any indemnified person of a notice of a claim or
the beginning of any action in respect of which indemnity is to be sought
against an indemnifying person pursuant to this Section 9.3, such indemnified
person shall notify the indemnifying person in writing of such claim or of the
commencement of such action, and, subject to the provisions hereinafter stated,
in case any such action shall be brought against an indemnified person and such
indemnifying person shall have been notified thereof, such indemnifying person
shall be entitled to participate therein, and, to the extent it shall wish, to
assume the defense thereof, with counsel reasonably satisfactory to such
indemnified person.  After notice from the indemnifying person to such
indemnified person of its election to assume the defense thereof, such
indemnifying person shall not be liable to such indemnified person for any legal
expenses subsequently incurred by such indemnified person in connection with the
defense thereof; provided, however, that if there exists or shall exist a
conflict of interest that would make it inappropriate, in the opinion of counsel
to the indemnified person, for the same counsel to represent both the
indemnified person and such indemnifying person or any affiliate or associate
thereof, the indemnified person shall be entitled to retain its own counsel at
the expense of such indemnifying person; provided, however, that no indemnifying
person shall be responsible for the fees and expenses of more than one separate
counsel for all indemnified parties.

     9.4 TERMINATION OF CONDITIONS AND OBLIGATIONS.  The conditions precedent
imposed by Section 4, Section 5 or this Section 9 upon the transferability of
the Shares shall cease and terminate as to any particular number of the Shares
when such Shares shall have been sold or otherwise disposed of in accordance
with the intended method of disposition set forth in the Registration Statement
covering such Shares or at such time as an opinion of counsel satisfactory to
the Company shall have been rendered to the effect that such conditions are not
necessary in order to comply with the Securities Act.

                                       11
<PAGE>
 
     9.5 INFORMATION AVAILABLE.  So long as the Registration Statement is
effective covering the resale of Shares owned by the Purchasers, the Company
will furnish to the Purchasers:

      (a) as soon as practicable after available (but in the case of the
Company's Annual Report to Stockholders, within 150 days after the end of each
fiscal year of the Company), one copy of (i) its Annual Report to Stockholders
(which Annual Report shall contain financial statements audited in accordance
with generally accepted auditing standards certified by a national firm of
certified public accountants); (ii) its Annual Report on Form 10-K; (iii) its
quarterly reports on Form 10-Q (the foregoing, in each case, excluding
exhibits); (iv) its Proxy Statement; and (v) its current reports on Form 8-K,
if any;

      (b) upon the request of any Purchaser, all exhibits excluded by the
parenthetical to subparagraph (a)(iii) of this Section 9.5, in the form
generally available to the public; and

      (c) upon the reasonable request of any Purchaser, an adequate number of
copies of the prospectuses and supplements to supply to any other party
requiring such prospectuses.



     9.6 CHANGES IN PURCHASER INFORMATION.  Each Purchaser agrees to promptly
notify the Company of any changes in the information set forth in the
Registration Statement regarding Purchaser or such Purchaser's plan of
distribution set forth in such Registration Statement.

                                       12
<PAGE>
 
     SECTION 10.  BROKER'S FEE.

     The Company and each Purchaser (severally and not jointly) hereby represent
that, except for amounts to be paid to the Placement Agent by the Company as
described in Section 12.8 hereof, there are no brokers or finders entitled to
compensation in connection with the sale of the Shares, and shall indemnify each
other for any such fees for which they are responsible.


     SECTION 11.  NOTICES.

     All notices, requests, consents and other communications hereunder shall be
in writing, shall be sent by confirmed facsimile or mailed by first-class
registered or certified airmail, or nationally recognized overnight express
courier, postage prepaid, and shall be deemed given when so sent in the case of
facsimile transmission, or when so received in the case of mail or courier, and
addressed as follows:

(a) if to the Company, to:

     Calypte Biomedical Corporation
     1440 Fourth Street
     Berkeley, California  94710
     Attention:  President and Chief Executive Officer
     Facsimile:  (510) 814-8408

   with a copy so mailed to:

     Heller Ehrman White & McAuliffe
     525 University Avenue
     Palo Alto, California  94301
     Attention:  Richard Friedman, Esq.
     Facsimile:  (650) 324-0638

     or to such other person at such other place as the Company shall designate
to the Purchasers in writing; and

(b) if to the Purchasers, at the address as set forth at the end of this
Agreement, or at such other address or addresses as may have been furnished to
the Company in writing.



     SECTION 12.  MISCELLANEOUS.

     12.1 WAIVERS AND AMENDMENTS.  Neither this Agreement nor any provision
hereof may be changed, waived, discharged, terminated, modified or amended
except upon the written consent of the Company and holders of at least a
majority of the Shares.

                                       13
<PAGE>
 
     12.2 HEADINGS.  The headings of the various sections of this Agreement
have been inserted for convenience of reference only and shall not be deemed
to be part of this Agreement.

     12.3 SEVERABILITY.  In case any provision contained in this Agreement
should be invalid, illegal or unenforceable in any respect, the validity,
legality and enforceability of the remaining provisions contained herein shall
not in any way be affected or impaired thereby.

     12.4 GOVERNING LAW.  This Agreement shall be governed by and construed in
accordance with the laws of the State of California as applied to contracts
entered into and performed entirely in California by California residents,
without regard to conflicts of law principles.

     12.5 COUNTERPARTS.  This Agreement may be executed in two or more
counterparts, each of which shall constitute an original, but all of which,
when taken together, shall constitute but one instrument, and shall become
effective when one or more counterparts have been signed by each party hereto
and delivered to the other parties.

     12.6 SUCCESSORS AND ASSIGNS.  Except as otherwise expressly provided
herein, the provisions hereof shall inure to the benefit of, and be binding
upon, the successors, assigns, heirs, executors and administrators of the
parties hereto.

     12.7 ENTIRE AGREEMENT.  This Agreement and other documents delivered
pursuant hereto, including the exhibits, constitute the full and entire
understanding and agreement between the parties with regard to the subjects
hereof and thereof.

     12.8 PAYMENT OF FEES AND EXPENSES.  Each of the Company and the
Purchasers shall bear its own expenses and legal fees incurred on its behalf
with respect to this Agreement and the transactions contemplated hereby (the
"Offering"); provided, that the Company shall reimburse the placement agent
retained in connection with the Offering (the "Placement Agent") for certain
fees and expenses incurred by the Placement Agent in connection with the
Offering. Purchasers acknowledge that the Placement Agent will receive a
commission. If any action at law or in equity is necessary to enforce or
interpret the terms of this Agreement, the prevailing party shall be entitled
to reasonable attorney's

                                       14
<PAGE>
 
fees, costs and necessary disbursements in addition to any other relief to which
such party may be entitled.

     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
executed by their duly authorized representatives as of the day and year first
above written.



                              CALYPTE BIOMEDICAL CORPORATION



                              By: /s/ John P. Davis
                                 ___________________________________________
                              Name:  John P. Davis
                              Title:  President and Chief Executive Officer


                              PURCHASER

                              Purchaser Name:
                                             _______________________________


                              By:
                                 ___________________________________________
                              Name:
                                   _________________________________________
                              Title:
                                    ________________________________________

                         Address:
                                 ___________________________________________

                                 ___________________________________________

                                 ___________________________________________
 

                         Facsimile:
                                 ___________________________________________

                                       15
<PAGE>
 
                                                                      APPENDIX I

                       CALYPTE BIOMEDICAL CORPORATION

                       STOCK CERTIFICATE QUESTIONNAIRE

     Pursuant to Section 3 of the Agreement, please provide us with the
following information:

1.  The exact name that your Shares are to     _________________________________
    be registered in (this is the name that
    will appear on your stock certificate(s)).
    You may use a nominee name if appropriate:

2.  The relationship between the Purchaser     _________________________________
    of the Securities and the Registered Holder
    listed in response to item 1 above:
3.  The mailing address and facsimile number   _________________________________
    of the Registered Holder listed in response_________________________________
    to item 1 above:                           _________________________________
                                               Facsimile: ______________________
 
 
4.  The Social Security Number or Tax          _________________________________
    Identification Number of the Registered
    Holder listed in the response to item 1
    above:


                              Signature:
                                        ________________________________________
                              Print Name:
                                         _______________________________________
                              Title:
                                    ___________________________________________
<PAGE>
 
                                                                     APPENDIX II
                                                                                
                       CALYPTE BIOMEDICAL CORPORATION

                    REGISTRATION STATEMENT QUESTIONNAIRE


     In connection with the preparation of the Registration Statement, please
provide us with the following information:

     1.    Please state your or your organization's name exactly as it should
appear in the Registration Statement:


     2.    Please provide the following information, as of September 30, 1997:

Number of Shares that you are          Number of shares of Common Stock that you
purchasing and seek to include in      already beneficially own or that you are
the Registration Statement             purchasing and do NOT seek to include in
                                             the Registration Statement

     3.    Have you or your organization had any position, office or other
material relationship within the past three years with the Company or its
affiliates other than as disclosed in the Proxy Statement in connection with
the Company's 1997 Annual Meeting of Stockholders?

                               Yes ___  No ___

     If yes, please indicate the nature of any such relationships: 
                                                                  ___________

_____________________________________________________________________________
            
 
                              Signature:
                                        _____________________________________
                              Print Name:
                                         ____________________________________
                              Title:
                                    _________________________________________
<PAGE>
 
                                                                    APPENDIX III

               PURCHASER'S CERTIFICATE OF RESALE OF THE SHARES

     The undersigned, an officer of, or other person duly authorized by
______________________________________ [fill in official name of individual or
institution] hereby certifies that he/she [said institution] is the Purchaser of
the Shares evidenced by the attached stock certificate(s) and as such, sold such
Shares on ________________ [date] in accordance with registration statement
number _________________________________ [fill in the number of or otherwise
identify registration statement] and the requirement of delivering a current
prospectus and current annual, quarterly and reports (Forms 10-K, 10-Q, and 8-K)
by the Company has been complied with in connection with such sale.


Print or Type:

Name of Purchaser (Individual or Institution):
                                              ________________________________
Name of Individual representing Purchaser

(if an Institution):
                                              ________________________________
Title of Individual representing Purchaser

(if an Institution):
                                              ________________________________


Signature by:


Individual Purchaser or Individual

representing Purchaser:
                                              ________________________________

<PAGE>
 
                                                                     EXHIBIT 5.1

                               October 21, 1997
                                      

                                                                      24073-0001


Calypte Biomedical Corporation
1440 Fourth Street
Berkeley, California 94710


                      Registration Statement on Form S-3
                      ----------------------------------

Ladies and Gentlemen:

  We have acted as counsel to Calypte Biomedical Corporation, a Delaware
corporation (the "Company"), in connection with the Registration Statement on
Form S-3 (the "Registration Statement") to be filed with the Securities and
Exchange Commission on or about October 21, 1997, for the purpose of registering
under the Securities Act of 1933, as amended, 2,600,999 shares of its Common
Stock, $.001 par value (the "Shares").  The Shares were issued to the holders
thereof pursuant to the Common Stock Purchase Agreement, dated October 17,
1997, (the "Agreement") among the Company and the purchasers named therein.

  In connection with this opinion, we have assumed the authenticity of all
records, documents and instruments submitted to us as originals, the genuineness
of all signatures, the legal capacity of natural persons and the conformity to
the originals of all records, documents and instruments submitted to us as
copies.  We have based our opinion upon our review of the following records,
documents and instruments:

          (a)  The Certificate of Incorporation of the Company certified by the
               Secretary of State of the State of Delaware as of October 10,
               1997 and certified to us by the Chief Financial Officer of the
               Company as being complete and in full force and effect as of the
               date of this opinion;

          (b)  The By-laws of the Company certified to us by the Chief Financial
               Officer and Secretary of the Company as being complete and in
               full force and effect as of the date of this opinion;

          (c)  Records certified to us by an officer of the Company as
               constituting all records of proceedings and actions of the Board
               of Directors of the Company relating to the issuance of the
               Shares;

          (d)  A letter from ChaseMellon Shareholder Services L.L.C., the
               Company's Transfer Agent, dated October 16, 1997 as to the number
               of shares of Common Stock that were outstanding as of October 15,
               1997;

          (e)  The Registration Statement; and

          (f)  The Agreement.
<PAGE>
 
Calypte Biomedical Corporation
October 21, 1997                                                          Page 2
       

  This opinion is limited to the federal law of the United States of America and
the General Corporation Law of the State of Delaware.  We disclaim any opinion
as to any other statute, rule, regulation, ordinance, order or other
promulgation of any other jurisdiction or any regional or local governmental
body.

  Our opinion expressed herein assumes that the Agreement was duly authorized,
executed and delivered by the parties thereto in the form that we have reviewed
as of the date of this opinion, and that the full consideration stated in the
Agreement and the Board of Directors minutes authorizing the issuance of the
Shares was paid.

  Based upon the foregoing and our examination of such questions of law as we
have deemed necessary or appropriate for the purpose of this opinion and
assuming that (i) the Registration Statement becomes and remains effective
during the period when the Shares are offered and sold; (ii) the Shares were
issued in accordance with the terms of the Agreement and the resolutions
authorizing their issuance; (iii) appropriate stock certificates evidencing the
Shares were executed and delivered; and (iv) all applicable securities laws are
complied with, it is our opinion that the Shares were duly authorized and
validly issued, and are fully paid and nonassessable.

  This opinion is rendered to you in connection with the Registration Statement
and is solely for your benefit.  This opinion may not be relied upon by you for
any other purpose, or relied upon by any other person, firm, corporation or
other entity for any purpose, without our prior written consent.  We disclaim
any obligation to advise you of any change of law that occurs, or any facts
which we become aware after the date of this opinion.
<PAGE>
 
Calypte Biomedical Corporation
October 21, 1997                                                          Page 3
       

  We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement.


                                           Very truly yours,

                                           /s/ Heller Ehrman White & McAuliffe  
                                           -----------------------------------  
                                             HELLER EHRMAN WHITE & MCAULIFFE

<PAGE>
 
                                                                    Exhibit 23.2


                      CONSENT OF INDEPENDENT ACCOUNTANTS
                      ----------------------------------


The Board of Directos 
Calypte Biomedical Corporation:

We consent to the use of our report incorporated hereon by reference and to the 
reference to our firm under the heading "Experts" in the Prospectus.



                                               /s/  KPMG Peat Marwick LLP


San Francisco, California
October 20, 1997


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