CALYPTE BIOMEDICAL CORP
S-3, 2000-03-13
LABORATORY ANALYTICAL INSTRUMENTS
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<PAGE>

        As filed with the Securities and Exchange Commission on March 13, 2000

                                                    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 Industrial         (I.R.S. employer
jurisdiction of)           Classification Code Number)         incorporation or
                                                                organizational)

      1265 HARBOR BAY PARKWAY, ALAMEDA, CALIFORNIA 94502, (510) 749-5100
  (Address, including zip code, and telephone number, including area code, of
                   registrant's principal executive offices)

                            ------------------------
                                  NANCY E. KATZ
                        President, Chief Operating Officer,
                       Chief Financial Officer and Director
                         Calypte Biomedical Corporation
                             1265 Harbor Bay Parkway
                            Alameda, California 94502
                                 (510) 749-5100

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

                            ------------------------
                                   Copies to:

                              BRUCE W. JENETT, 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. / /

<TABLE>
<CAPTION>
                                      CALCULATION OF REGISTRATION FEE

===============================================================================================================
                                                     PROPOSED             PROPOSED
                                    AMOUNT           MAXIMUM              MAXIMUM
TITLE OF SHARES TO BE REGISTERED    TO BE          OFFERING PRICE        AGGREGATE              AMOUNT OF
                                  REGISTERED (1)    PER SHARE (2)      OFFERING PRICE        REGISTRATION FEE
===============================================================================================================
<S>                                <C>              <C>                 <C>                   <C>
Common Stock, $.001 par value...   4,196,000        $ 3.91              $16,406,360           $4,331.28
===============================================================================================================
</TABLE>

(1)  In accordance with Rule 416 under the Securities Act of 1933, Common Stock
     offered shall also be deemed to cover additional securities to be offered
     or issued to prevent dilution resulting from stock splits, stock dividends
     or similar transactions.

(2)  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 March
     8, 2000.

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 MARCH 13, 2000

PROSPECTUS

                         CALYPTE BIOMEDICAL CORPORATION
                        4,196,000 Shares of Common Stock

         The stockholders of Calypte Biomedical Corporation identified on page
__ may offer and sell the shares covered by this prospectus from time to time.
The selling stockholders will receive all of the proceeds from the sale of the
shares and will pay all underwriting discounts and selling commissions, if any,
applicable to the sale of the shares. Calypte will pay the expenses of
registration of the sale of the shares.

    Our common stock trades on the Nasdaq SmallCap Market under the symbol
"CALY". On March 9, 2000, the last reported sale price of our common stock on
the Nasdaq SmallCap Market was $5.13 per share.

BEGINNING ON PAGE 2, WE HAVE LISTED SEVERAL "RISK FACTORS" WHICH YOU SHOULD
CONSIDER. YOU SHOULD READ THE ENTIRE PROSPECTUS CAREFULLY BEFORE YOU MAKE YOUR
INVESTMENT DECISION.

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

         The Securities and Exchange Commission and state regulatory authorities
have not approved or disapproved these securities, or determined if this
prospectus is truthful or complete. Any representation to the contrary is a
criminal offense.

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


         The Date of this Prospectus is                , 2000

<PAGE>

                                  RISK FACTORS

YOU SHOULD CONSIDER CAREFULLY THE FOLLOWING RISK FACTORS, ALONG WITH THE OTHER
INFORMATION CONTAINED OR INCORPORATED BY REFERENCE IN THIS PROSPECTUS, IN
DECIDING WHETHER TO INVEST IN OUR SHARES. THESE FACTORS, AMONG OTHERS, MAY CAUSE
ACTUAL RESULTS, EVENTS OR PERFORMANCE TO DIFFER MATERIALLY FROM THOSE EXPRESSED
IN ANY FORWARD-LOOKING STATEMENTS MADE IN THIS PROSPECTUS.

UNCERTAIN MARKET ACCEPTANCE OF OUR NEW METHOD OF DETERMINING THE PRESENCE OF HIV
ANTIBODIES. Our products incorporate a new method of determining the presence of
HIV antibodies. There can be no assurance that we will obtain:

     - any significant degree of market acceptance among physicians, patients or
       health care payors; or

     - recommendations and endorsements by the medical community which are
       essential for market acceptance of the products.

We have FDA approval to market our urine HIV-1 screening and confirmatory test
in the United States and in July, 1998 we began marketing this product. However,
to date this product has only generated limited revenues and not achieved
significant market penetration. The failure of our products to obtain market
acceptance would have a material adverse effect on us.

WE HAVE LIMITED EXPERIENCE SELLING AND MARKETING OUR HIV-1 URINE-BASED
SCREENING TEST.We have little experience marketing and selling our products
either directly or through our distributors. The success of our products
depends upon alliances with third-party distributors including the
distribution agreement announced in September, 1999 with Carter Wallace Inc.
There can be no assurance that:

     - our direct selling efforts will be effective;

     - our distributors will successfully market our products; or

     - if our relationships with distributors terminate, we will be able to
       establish relationships with other distributors on satisfactory terms, if
       at all.

Any disruption in our distribution, sales or marketing network could have a
material adverse effect on us.

WE HAVE SUSTAINED LOSSES IN THE PAST AND WE EXPECT TO SUSTAIN LOSSES IN THE
FUTURE. We have incurred losses in each year since our inception. Our net loss
for the nine months ended September 30, 1999 was $7.6 million and our
accumulated deficit as of September 30, 1999 was $64.3 million. We expect
operating losses to continue as we continue our marketing and sales activities
of our FDA-approved products and conduct additional research and development for
subseqent products.

OUR QUARTERLY RESULTS MAY FLUCTUATE DUE TO CERTAIN REGULATORY, MARKETING AND
COMPETITIVE FACTORS OVER WHICH WE HAVE LITTLE OR NO CONTROL. The factors listed
below, some of which we can not control, may cause our revenues and results of
operations to fluctuate significantly:

     - actions taken by the FDA or foreign regulatory bodies relating to our
       products;

     - the extent to which our products and our Sentinel HIV and STD testing
       service gain market acceptance;

     - the timing and size of distributor purchases; and

     - introductions of alternative means for testing for HIV by competitors.

WE MAY NOT BE ABLE TO OBTAIN ADDITIONAL FINANCING THAT WE MAY NEED IN THE
FUTURE. The report of KPMG LLP covering the December 31, 1998, consolidated
financial statements contains an explanatory paragraph that states that our
recurring losses from operations and accumulated deficit raise substantial
doubt about our ability to continue as a going concern. The consolidated
financial statements do not include any adjustments that might result from
the outcome of that uncertainty. We believe that we may need to raise more
money to continue to finance our operations. We may not be able to obtain
additional financing on acceptable terms, or at all. Any failure to raise
additional financing will likely place us in significant financial jeopardy.

We believe that we may need to raise more money to continue to finance our
operations. We may not be able to obtain additional financing on acceptable
terms. Any failure to obtain additional financing will likely place us in
significant financial jeopardy.

                                       2

<PAGE>

WE DEPEND UPON THE VIABILITY OF THREE PRODUCTS--OUR HIV-1 URINE-BASED SCREENING
TEST AND OUR URINE AND BLOOD-BASED SUPPLEMENTAL TESTS. Our HIV-1 urine-based
screening test and our urine and blood-based supplemental tests are our only
products. Accordingly, we may have to cease operations if our tests fail to
achieve market acceptance or generate significant revenues.

WE WILL DEPEND UPON THE SUCCESS OF THE SENTINEL HIV AND STD TESTING SERVICE
FOR SIGNIFICANT FUTURE REVENUES. The service is expected to be launched to
medical clinics and physicians in the second quarter of 2000. Accordingly, we
may have to cease operations if the Sentinel service fails to achieve market
acceptance or generate significant revenues.

OUR PRODUCTS DEPEND UPON RIGHTS TO TECHNOLOGY THAT WE HAVE LICENSED FROM
THIRD PARTY PATENT HOLDERS AND THERE CAN BE NO ASSURANCE THAT THE RIGHTS WE
HAVE UNDER THESE LICENSING AGREEMENTS ARE SUFFICIENT OR THAT WE CAN
ADEQUATELY PROTECT THOSE RIGHTS. We currently have the right to use patent
and proprietary rights which are material to the manufacture and sale of our
HIV-1 urine-based screening test under licensing agreements with New York
University, Repligen and the Texas A&M University System.

WE RELY ON SOLE SOURCE SUPPLIERS THAT WE CANNOT QUICKLY REPLACE FOR CERTAIN
COMPONENTS CRITICAL TO THE MANUFACTURE OF OUR PRODUCTS. Any delay or
interruption in the supply of these components could have a material adverse
effect on us by significantly impairing our ability to manufacture products in
sufficient quantities, particularly as we increase our manufacturing activities
in support of commercial sales.

WE HAVE LIMITED EXPERIENCE IN MANUFACTURING OUR PRODUCTS AND LITTLE EXPERIENCE
IN MANUFACTURING OUR PRODUCTS IN COMMERCIAL QUANTITIES. We may 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 SUCCESS OF OUR PLANS TO ENTER INTERNATIONAL MARKETS MAY BE LIMITED OR
DISRUPTED DUE TO RISKS RELATED TO INTERNATIONAL TRADE AND MARKETING AND THE
CAPABILITIES OF OUR DISTRIBUTORS. We anticipate that international distributor
sales will generate a significant portion of our revenues for the next several
years. We believe that our urine-based test can provide significant benefits in
countries that do not have the facilities or personnel to safely and effectively
collect and test blood samples. The following risks may limit or disrupt our
international sales:

     - 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.

    Some of our distributors have limited international marketing experience.
There can be no assurance that these distributors will be able to market
successfully our products in foreign markets.

WE FACE INTENSE COMPETITION IN THE MEDICAL DIAGNOSTIC PRODUCTS MARKET AND RAPID
TECHNOLOGICAL ADVANCES BY COMPETITORS. Competition in our diagnostic market is
intense and we expect it to increase. Within the United States, our competitors
include a number of well-established manufacturers of HIV tests using blood
samples, plus at least one system for the detection of HIV antibodies using oral
fluid samples. Many of our competitors have significantly greater financial,
marketing and distribution resources than we do. Our competitors may succeed in
developing or marketing technologies and products that are


                                       3
<PAGE>

more effective than ours. These developments could render our technologies or
products obsolete or noncompetitive or otherwise have a material adverse effect
on us.

OUR ABILITY TO MARKET OUR PRODUCTS DEPENDS UPON OBTAINING AND MAINTAINING FDA
AND FOREIGN REGULATORY APPROVALS. Numerous governmental authorities in the
United States and other countries regulate our products. The FDA regulates
our products under federal statutes and regulations related to pre-clinical
and clinical testing, manufacturing, labeling, distribution, sale and
promotion of medical devices in the United States.

    If we fail to comply with FDA regulations, or the FDA believes that we are
not in compliance with such regulations, the FDA can:

     - detain or seize our products;

     - issue a recall of our products;

     - prohibit marketing and sales of our products; and

     - assess civil and criminal penalties against us, our officers or our
       employees.

    We also plan to sell our products in certain foreign countries where they
may be subject to similar local regulatory requirements. The imposition of any
of the sanctions described above could have a material adverse effect on us.

    The regulatory approval process in the United States and other countries is
expensive, lengthy and uncertain. We may not obtain necessary regulatory
approvals or clearances in a timely manner, if at all. We may lose previously
obtained approvals or clearances or fail to comply with regulatory requirements.
The occurrence of any of these events would have a material adverse effect on
Calypte.

    Before we begin to manufacture our product at the Alameda facility, we must
obtain FDA approval for that facility. Delays in receiving the FDA's approval or
other difficulties which we encounter in scaling-up our manufacturing capacity
to meet demand could have a material adverse effect on us.

WE HAVE RECEIVED WARNING LETTERS FROM THE FDA REGARDING THE SUFFICIENCY OF
OUR MANUFACTURING RECORDS AND PRODUCTION PROCEDURES AND WE MUST SATISFY THE
FDA'S CONCERNS IN ORDER TO AVOID REGULATORY ACTION AGAINST US. On November
19, 1998, we received a Warning Letter from the FDA following an inspection
of our manufacturing facility in Berkeley, California. On December 11, 1998
we responded to the Warning Letter in writing to each of the alleged
deficiencies cited in the Warning Letter. Subsequently we received a letter
from the FDA in which the FDA requested further responses from the Company
with regard to certain of the alleged deficiencies. We responded to the
subsequent letter on June 1, 1999. On September 28, 1999, the FDA conducted a
follow up inspection of the our Berkeley and Alameda, California facilities
which resulted in observations requiring corrective action or response from
us. On November 4, 1999 we responded in writing to each of the FDA's
observations and we are awaiting the FDA's reply. If the FDA is not satisfied
with our responses and our corrective actions, it could take regulatory
actions against us including license suspension, revocation, and/or denial,
seizure and/or injunction, and/or civil penalties or criminal sanctions. Any
such FDA action is likely to have a material adverse effect upon our ability
to conduct operations. In addition, failure to satisfy the FDA as to the
Warning Letter may adversely affect receiving approval for the Alameda
facility. [UPDATE]

In May 1999, we received a Warning Letter from the FDA following an
inspection by the FDA of our manufacturing plant in Rockville, Maryland. The
Warning Letter was based upon an inspection of the Rockville manufacturing
facility that was conducted between November 30 and December 11, 1998, which
cited a number of significant observations. On May 24, 1999, we responded in
writing to each of the alleged deficiencies cited in the Warning Letter. On
November 19, 1999 we received a letter from the FDA stating that our
responses were considered adequate, and the Warning Letter was formally
closed. Between November 30 and December 9, 1999 the FDA conducted a
follow-up inspection of our Rockville manufacturing facility which resulted
in observations requiring corrective action or response from us. On January
7, 2000, we responded in writing to each of the FDA observations and we are
awaiting the FDA's reply. If the FDA is not satisfied with our responses and
our corrective actions, it could take regulatory actions against us including
license suspension, revocation, or denial, seizure of products or injunction,
or civil penalties or criminal sanctions. Any such FDA action would have a
material adverse effect upon the Company's ability to conduct operations. In
addition, failure of the Company to satisfy the FDA as to such Warning Letter
could adversely affect the Company's pending FDA license application for the
Rockville facility.

AS A SMALL MANUFACTURER OF A MEDICAL DIAGNOSTIC PRODUCT, WE ARE EXPOSED TO
PRODUCT LIABILITY AND RECALL RISKS FOR WHICH INSURANCE COVERAGE IS EXPENSIVE,
LIMITED AND POTENTIALLY INADEQUATE. We manufacture medical diagnostic products
which subjects us to risks of product liability claims or product recalls,
particularly in the event of false positive or false negative reports. A product
recall or a successful product liability claim or claims which exceed our
insurance coverage could have a material adverse effect on us. We maintain a
$10,000,000 claims-made policy of product liability insurance. However, product
liability insurance is expensive. In the future we may not be able to obtain
coverage on acceptable terms, if at all. Moreover, our insurance coverage may
not adequately protect us from liabilities which we incur in connection with
clinical trials or sales of our products.


                                       4

<PAGE>

OUR CHARTER DOCUMENTS MAY INHIBIT A TAKEOVER. Certain provisions of our
Certificate of Incorporation and Bylaws could:

     - discourage potential acquisition proposals;

     - delay or prevent a change in control of Calypte;

     - diminish stockholders' opportunities to participate in tender offers for
       our common stock, including tender offers at prices above the then
       current market price; or

     - inhibit increases in the market price of our common stock that could
       result from takeover attempts.

WE HAVE ADOPTED A STOCKHOLDER RIGHTS PLAN THAT HAS CERTAIN ANTI-TAKEOVER
EFFECTS. On December 15, 1998, the Board of Directors of Calypte declared a
dividend distribution of one preferred share purchase right for each outstanding
share of Common Stock of the Company. The dividend is payable to the
stockholders of record on January 5, 1999 with respect to each share of Common
Stock issued thereafter until a subsequent "distribution date" defined in a
Rights Agreement and, in certain circumstances, with respect to shares of Common
Stock issued after the Distribution Date.

    The rights have certain anti-takeover effects. The rights will cause
substantial dilution to a person or group that attempts to acquire the Company
without conditioning the offer on the rights being redeemed or a substantial
number of rights being acquired. However, the rights should not interfere with
any tender offer, or merger, which is approved by us because the rights do not
become exercisable in the event of an offer or other acquisition exempted by
Calypte's Board of Directors.

AN INVESTOR'S ABILITY TO TRADE OUR COMMON STOCK MAY BE LIMITED BY TRADING
VOLUME. The trading volume in our common shares has been relatively limited. A
consistently active trading market for our common stock may not develop.

WE MAY BE REMOVED FROM THE NASDAQ SMALLCAP MARKET IF WE FAIL TO MEET CERTAIN
MAINTENANCE CRITERIA. The Nasdaq Stock Market inquired on two occasions whether
we continue to meet the maintenance criterion for trading on the Nasdaq SmallCap
Market. We currently meet the maintenance criterion but our ability to continue
to do so will depend on whether we are able to maintain net tangible assets of
at least $2,000,000 and whether the minimum bid price for our common stock
exceeds $1.00 per share for at least ten consecutive business days during any
period of 120 consecutive business days. The public trading volume of our common
stock and the ability of our stockholders to sell their shares could be
significantly impaired if we fail to meet the maintenance criteria and are
removed from the Nasdaq SmallCap Market. In that case, our common stock would
trade on either the OTC bulletin board, a regional exchange or in the pink
sheets, which would likely result in an even more limited trading volume.

THE PRICE OF CALYPTE'S COMMON STOCK HAS BEEN HIGHLY VOLATILE DUE TO SEVERAL
FACTORS WHICH WILL CONTINUE TO EFFECT THE PRICE OF OUR STOCK. Our common stock
has traded as low as $0.69 per share and as high as $4.88 per share between
early-November 1999 and early-March 2000. Some of the factors leading to this
volatility include:

     - price and volume fluctuations in the stock market at large which do not
       relate to our operating performance;

     - fluctuations in our operating results;

     - announcements of technological innovations or new products which we or
       our competitors make;

     - FDA and international regulatory actions;

     - availability of reimbursement for use of our products from private health
       insurers, governmental health administration authorities and other
       third-party payors;

     - developments with respect to patents or proprietary rights;

     - public concern as to the safety of products that we or others develop;


                                       5

<PAGE>

     - changes in health care policy in the United States or abroad;

     - changes in stock market analysts' recommendations regarding Calypte,
       other medical products companies or the medical product industry
       generally; and

     - fluctuations in market demand for and supply of our products.

CALYPTE AND THE PRICE OF CALYPTE SHARES MAY BE ADVERSELY EFFECTED BY THE PUBLIC
SALE OF A SIGNIFICANT NUMBER OF THE SHARES ELIGIBLE FOR FUTURE SALE. All
outstanding shares of our common stock are freely tradable. Sales of common
stock in the public market could materially adversely affect the market price of
our common stock. Such sales also may inhibit our ability to obtain future
equity or equity-related financing on acceptable terms.

OUR RESEARCH AND DEVELOPMENT OF HIV URINE TESTS INVOLVES THE CONTROLLED USE OF
HAZARDOUS MATERIALS. There can be no assurance that our safety procedures for
handling and disposing of hazardous materials such as azide will comply with
applicable regulations. In addition, we cannot eliminate the risk of accidental
contamination or injury from these materials. We may be held liable for damages
from such an accident and that liability could have a material adverse effect on
us.

WE MAY NOT BE ABLE TO RETAIN OUR KEY EXECUTIVES AND RESEARCH AND DEVELOPMENT
PERSONNEL. As a small company with only 60 employees, our success depends on
the services of key employees in executive and research and development
positions. The loss of the services of one or more of such employees could have
a material adverse effect on us.


                                       6

<PAGE>

     You should rely only on the information contained in this prospectus. We
have not authorized anyone to provide you with information different from that
contained in this prospectus. The selling stockholders are offering to sell, and
seeking offers to buy, shares of our common stock only in jurisdictions where
offers and sales are permitted. The information contained in this prospectus is
accurate only as of the date of this prospectus, regardless of the time of
delivery of this prospectus or of any sale of the shares.

                       WHERE YOU CAN FIND MORE INFORMATION

    We file annual, quarterly, and current reports, proxy statements, and other
documents with the Securities and Exchange Commission. You may read and copy any
document we file at the SEC's public reference room at Judiciary Plaza Building,
450 Fifth Street, NW, Room 1024, Washington, D.C. 20549. You should call
1-800-SEC-0330 for more information on the public reference room. The SEC
maintains an internet site at http://www.sec.gov where certain information
regarding issuers (including Calypte) may be found.

    This prospectus is part of a registration statement that we filed with the
SEC (Registration No. 333-______). The registration statement contains more
information than this prospectus regarding Calypte and its common stock,
including certain exhibits and schedules. You can get a copy of the registration
statement from the SEC at the address listed above or from its internet site.

                       DOCUMENTS INCORPORATED BY REFERENCE

    The SEC allows us to "incorporate" into this prospectus information we file
with the SEC in other documents. This means that we can disclose important
information to you by referring to other documents that contain that
information. The information may include documents filed after the date of this
prospectus which update and supersede the information you read in this
prospectus. We incorporate by reference the documents listed below, except to
the extent information in those documents is different from the information
contained in this prospectus, and all future documents filed with the SEC under
Sections 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act of 1934 until
we terminate the offering of these shares.

<TABLE>
<CAPTION>
             SEC FILING
          (FILE NO. 0-20985)                  PERIOD/FILING DATE
- ------------------------------------    ---------------------------------------
<S>                                    <C>
Annual Report on Form 10-K               Year ended December 31, 1998

Quarterly Report on Form 10-Q            Quarter ended March 31, 1999
Quarterly Report on Form 10-Q            Quarter ended June 30, 1999
Quarterly Report on Form 10-Q            Quarter ended September 30, 1999

Description of common stock contained    July 10, 1996
in Registration Statements on Form 8-A   December 16, 1998
</TABLE>

     You may request a copy of these documents, at no cost, by writing to:

        Calypte Biomedical Corporation
        1265 Harbor Bay Parkway
        Alameda, California 94502
        Attention: President
        Telephone: (510) 749-5100.

                           FORWARD-LOOKING INFORMATION

    Statements made in this prospectus or in the documents incorporated by
reference herein that are not statements of historical fact are forward-looking
statements within the meaning of Section 27A of the Securities Act of 1933, and
Section 21E of the Securities Exchange Act of 1934. A number of risks and
uncertainties, including those discussed under the caption "Risk Factors" above
and the documents incorporated by reference herein could affect such
forward-looking statements and could cause actual results to differ materially
from the statements made.

                                       7
<PAGE>

                                 CAPITALIZATION

         The following table sets forth the actual capitalization of Calypte
at September 30, 1999. The table also sets forth the actual capitalization
pro forma and as adjusted for the sale of the 4,096,000 shares that
purchasers in the Common Stock Purchase Agreement dated March 2, 2000 agreed
to buy at a price of $2.05 per share and for the issuance of 100,000 shares
upon the exercise of a warrant held by Trilobite Lakes Corp., one of the
selling stockholders, at $3.62 per share. The table includes the application
of the net proceeds receivable upon closing of the sale and exercise of the
warrants after payment of the estimated expenses of the sale.

<TABLE>
<CAPTION>
                                                                                             SEPTEMBER 30, 1999
                                                                                          -----------------------
                                                                                                       PRO FORMA
                                                                                                        AND AS
                                                                                           ACTUAL       ADJUSTED
                                                                                          ----------  -----------
                                                                                           (IN THOUSANDS, EXCEPT
                                                                                            SHARE AND PER SHARE
                                                                                                   DATA)
<S>                                                                                       <C>          <C>
Long-term portion of capital lease obligations..........................................  $       60   $      60
                                                                                          ----------  -----------
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......................................................       2,186       2,186
                                                                                          ----------  -----------
Stockholders' equity
  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, 30,000,000 shares authorized; 20,415,650 shares issued
    and outstanding, as of September 30, 1999; 24,611,650 shares issued and outstanding,
    as adjusted.........................................................................          20          24
Additional paid-in capital..............................................................      68,143      76,893
Deferred compensation...................................................................         (51)        (51)
Accumulated deficit.....................................................................     (64,271)    (64,271)
                                                                                          ----------  -----------
Total stockholders' equity..............................................................  $    3,841  $   12,595

Total capitalization....................................................................  $    6,087  $   14,841
                                                                                          ----------  -----------
                                                                                          ----------  -----------
</TABLE>


                                       8

<PAGE>

                              SELLING STOCKHOLDERS

         The following table sets forth the names of the selling stockholders
and the number of shares that may be offered pursuant to this prospectus. The
table also includes the number of shares of common stock issuable upon the
exercise of a warrant owned beneficially by the one of the selling stockholders,
Trilobite Lakes Corp. 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.

         On March 2, 2000, Calypte sold 4,096,000 shares of common stock in a
private placement to the selling stockholders at a price of $2.05 per share. The
prospectus covers the resale by those selling stockholders of the 4,096,000
shares issued in the private placement and 100,000 shares issuable upon the
exercise of a warrant at $3.62 per share issued to Trilobite Lakes Corp., one of
the selling stockholders. The warrant was issued to Trilobite in connection with
a credit line of $1,000,000 provided to Calypte by Trilobite in the form of a
convertible bridge loan. The private placement was exempt from the registration
requirements of the Securities Act of 1933 pursuant to Rule 506 of Regulation D
of the Act.

         The applicable percentage of ownership listed below is based on
20,481,153 shares of Common Stock outstanding as of March 1, 2000 and, with
respect to Trilobite, assumes the exercise of Trilobite's warrant for the
purchase of Common Stock.

         The individuals and entities listed in parentheses in the table have
certain affiliations with the selling stockholder listed immediately above such
individuals and entities. However, the individuals and entities so listed
disclaim beneficial ownership of the shares.

<TABLE>
<CAPTION>
                                                     COMMON STOCK                              COMMON STOCK
                                                     BENEFICIALLY OWNED          COMMON        BENEFICIALLY OWNED
                                                     PRIOR TO OFFERING           STOCK         AFTER OFFERING
                                                                                 TO BE
HOLDER                                                   NUMBER    PERCENT       SOLD          NUMBER   PERCENT
- -----------------------------------------------------------------------------------------------------------------
<S>                                                   <C>          <C>         <C>          <C>          <C>
Apollo Medical Partners LP..............................200,000       *          200,000          --         --
  (Brandon Fradd, Managing Director)
Atlas II, LP............................................718,895      2.93%       318,895       400,000     1.63 %
  (Richard Jacinto, General Partner)
Brooks Industry of Long Island Profit Sharing Trust......76,080       *           76,080          --         --
  (David Brooks)
Clarion Group (1).......................................680,055      3.10%       487,805       192,250        *
  (Morton A. Cohen)
Hollis Capital..........................................122,000       *          122,000          --         --
  (Paul J. Siegal, Principal)
Kane & Co...............................................802,500      3.27%       200,000       602,500     2.45 %
  (Hathaway Associates, Investment Advisor)
Minotaur Fund L.P.......................................900,000      3.66%       150,000       750,000     3.05 %
  (Corfman Capital, Investment Advisor)
Special Situations Private Equity Fund, LP..............590,000      2.40%       590,000          --         --
  (Austin Marxe, Managing Director)
Trilobite Lakes Corp. (2) (3).........................2,051,220      8.31%     2,051,220          --         --

                                                      -----------------------------------------------------------
TOTALS                                                6,140,750     23.07%     4,196,000     1,944,750     7.91 %
</TABLE>

- -------------------------------------
*    Less than 1%

(1) Includes 436,152 shares held by Clarion Capital Corporation, 207,318
shares held by Clarion Partners, LP and 36,585 shares held by Clarion
Offshore Fund, Ltd. prior to the offering and 192,250 shares held by Clarion
Capital Corporation after the offering. Each entity so listed shares certain
affiliations with one another. However, each such entity disclaims beneficial
ownership of shares held in the name of any other such entity.

(2) Pursuant to the Common Stock Purchase Agreement dated March 2, 2000, a
representative designated by Trilobite Lakes Corp. will be elected to Calypte's
Board of Directors to serve until the 2000 annual stockholders meeting. The
Calypte board will also nominate a representative selected by Trilobite for
election to the Calypte board at each subsequent annual meeting for so long as
Trilobite holds at least one-half of the shares it acquired through the Common
Stock Purchase Agreement.

(3) Trilobite Lakes Corp. is an affiliate of Claneil Enterprises, Inc. David
Collins, the Chief Executive Officer and a director of Calypte serves on the
Board of Directors of Claneil and is chairman of Claneil's compensation
committee.

                                       9

<PAGE>

                              PLAN OF DISTRIBUTION

    The selling stockholders may offer their shares at various times in one or
more of the following transactions:

     - on the Nasdaq SmallCap Market (or any other exchange on which the shares
       may be listed);

     - in the over-the-counter market;

     - in negotiated transactions other than on such exchanges;

     - by pledge to secure debts and other obligations;

     - in connection with the writing of non-traded and exchange-traded call
       options, in hedge transactions, in covering previously established short
       positions and in settlement of other transactions in standardized or
       over-the-counter options; or

     - in a combination of any of the above transactions.

    The selling stockholders may sell their shares at market prices prevailing
at the time of sale, at prices related to such prevailing market prices, at
negotiated prices or at fixed prices. The selling stockholders may use
broker-dealers to sell their shares. The broker-dealers will either receive
discounts or commissions from the selling stockholders, or they will receive
commissions from purchasers of shares.

    Under certain circumstances the selling stockholders and any broker-dealers
that participate in the distribution may be deemed to be "underwriters" within
the meaning of the Securities Act. Any commissions received by such
broker-dealers and any profits realized on the resale of shares by them may be
considered 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,
Calypte has agreed to indemnify the selling stockholders with respect to the
shares offered hereby against certain liabilities, including certain liabilities
under the Securities Act. Alternatively, Calypte may contribute toward amounts
paid due to such liabilities.

    Under the rules and regulations of the Exchange Act, any person engaged in
the distribution of the resale of shares may not simultaneously engage in market
making activities with respect to the Calypte's common stock for a period of two
business days prior to the commencement of such distribution. The selling
stockholders will also be subject to applicable provisions of the Exchange Act
and regulations under the Exchange Act which may limit the timing of purchases
and sales of shares of Calypte'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
Calypte, and Calypte has paid the expenses of the preparation of this
prospectus. We have not made any underwriting arrangements with respect to the
sale of shares offered hereby.

                                 USE OF PROCEEDS

    We will not receive any of the proceeds from the sale of the shares by the
selling stockholders.


                                       10
<PAGE>

                                  LEGAL MATTERS

    Heller Ehrman White & McAuliffe of Palo Alto, California, our counsel in
connection with the offering, has issued an opinion about the validity of the
securities being offered.

                                     EXPERTS

     The consolidated financial statements of Calypte Biomedical Corporation and
subsidiary as of December 31, 1998 and 1997, and for each of the years in the
three-year period ended December 31, 1998, have been incorporated by reference
herein and in the registration statement in reliance upon the report of KPMG
LLP, independent certified public accountants, incorporated by reference herein,
and upon the authority of said firm as experts in accounting and auditing.

     The report of KPMG LLP covering the December 31, 1998, consolidated
financial statements contains an explanatory paragraph that states that the
Company's recurring losses from operations and accumulated deficit raise
substantial doubt about the entity's ability to continue as a going concern.
The consolidated financial statements do not include any adjustments that
might result from the outcome of that uncertainty.


                                       11

<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>
<S>                                                                 <C>
     Securities and Exchange Commission Registration Fee  . . . . . $  4,561
     Legal fees and expenses . . . . . . . . . . . . . .  . . . . .   30,000
     Accounting fees and expenses. . . . . . . . . . . .  . . . . .   15,000
     Miscellaneous . . . . . . . . . . . . . . . . . . .  . . . . .    6,011
                                                                     -------
     Total . . . . . . . . . . . . . . . . . . . . . . .  . . . . . $ 55,572
                                                                     -------
                                                                     -------
</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.

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

ITEM 16. EXHIBITS

<TABLE>
<CAPTION>
  EXHIBIT                  DESCRIPTION
- --------------------------------------------------------------------------------
  <S>                      <C>
       4.1                 Common Stock Purchase Agreement between Calypte and
                           the selling stockholders, dated March 2, 2000
       4.2                 Bridge Loan Agreement  between Calypte and Trilobite
                           Lakes Corp., dated as of March 2, 2000.
       4.3                 Form of Convertible Bridge Promissory Note.
       4.4                 Form of Warrant
       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 LLP, Independent Auditors
      24.1                 Power of Attorney (See page II-3)

- - ------------------------
</TABLE>

                                      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 on Form S-3 to be signed on its behalf by the undersigned, thereunto
duly authorized, in the city of Alameda, State of California, on March 10, 2000.

                                   CALYPTE BIOMEDICAL CORPORATION


                                   By: /s/ Nancy E. Katz
                                      -----------------------------------------
                                                   Nancy E. Katz
                                          PRESIDENT, CHIEF OPERATING OFFICER,
                                         CHIEF FINANCIAL OFFICER AND DIRECTOR

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement on Form S-3 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/ David Collins                               Chief Executive Officer and Director                       March 10, 2000
- ---------------------------------------
              David Collins

/s/ Nancy E. Katz*                              President, Chief Operating Officer, Chief Financial        March 10, 2000
- ---------------------------------------         Officer and Director

              Nancy E. Katz

/s/ William A. Boeger                           Chairman of Board of Directors                             March 10, 2000
- ---------------------------------------
            William A. Boeger

/s/ Howard B. Urnovitz, Ph.D.                   Chief Science Officer and Director                         March 10, 2000
- ---------------------------------------
        Howard B. Urnovitz, Ph.D.

/s/ John J. DiPietro                            Director                                                   March 10, 2000
- ---------------------------------------
             John J. DiPietro


/s/ Paul Freiman                                Director                                                   March 10, 2000
- ---------------------------------------
               Paul Freiman


/s/ Julius R. Krevans, M.D.                     Director                                                   March 10, 2000
- ---------------------------------------
         Julius R. Krevans, M.D.


/s/ Mark Novitch, M.D.                          Director                                                   March 10, 2000
- ---------------------------------------
            Mark Novitch, M.D.


/s/ Zafar I. Randawa, Ph.D.                     Director                                                   March 10, 2000
- ---------------------------------------
         Zafar I. Randawa, Ph.D.

/s/ Nancy E. Katz
- ---------------------------------------
              *Nancy E. Katz
            (Attorney-in-Fact)
</TABLE>


                                      II-3
<PAGE>

                         CALYPTE BIOMEDICAL CORPORATION

                                INDEX TO EXHIBITS
<TABLE>
<CAPTION>
      EXHIBIT NO.      DESCRIPTION
- -------------------------------------------------------------------------------
<S>              <C>
         4.1      Common Stock Purchase Agreement between Calypte and the
                  selling stockholders, dated March 2, 2000

         4.2      Bridge Loan Agreement between Calypte and Trilobite Lakes
                  Corp., dated as of March 2, 2000

         4.3      Form of Promissory Note

         4.4      Form of Warrant

         5.1      Opinion of Heller Ehrman White & McAuliffe

         23.1     Consent of Heller Ehrman White & McAuliffe (filed as part of
                  Exhibit 5)

         23.2     Consent of KPMG LLP, Independent Auditors

         24.1     Power of Attorney (See page II-3)
</TABLE>
- -------------------------

<PAGE>
                                                                     Exhibit 4.1

                         CALYPTE BIOMEDICAL CORPORATION


                                  COMMON STOCK

                               PURCHASE AGREEMENT


                                 MARCH 2, 2000



<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 March 2, 2000 (the
"Execution 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 4,096,000 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 Two Dollars and Five Cents ($2.05)
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.

         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 effectiveness of the Registration Statement, as set
forth in Section 9.1(a) hereof, to be filed 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.

<PAGE>

         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.

         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


                                       2
<PAGE>

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 shareholders of the Company or any liens or
encumbrances. Such issuance and delivery will not cause neither an increase in
the number of shares issuable pursuant to any securities of the Company that are
outstanding as of the Execution Date nor a decrease in the exercise or
conversion price, of any such securities.

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

         4.5      INTELLECTUAL PROPERTY. 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 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


                                       3
<PAGE>

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 September 30, 1999, 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.

         4.10     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      REPRESENTATIONS AND WARRANTIES. 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


                                       4
<PAGE>

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).

                  (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 Documents, the representations and warranties of the Company
contained herein and oral statements of the Company's management made at
meetings with the 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      RESTRICTION ON SHORT SALES. 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      NO ADVICE PROVIDED. 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


                                       5
<PAGE>

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.

         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 EFFECTIVE. The Registration Statement
filed by the Company pursuant to Section 9 shall have become effective, and no
stop order suspending the effectiveness thereof shall have been issued and no
proceedings therefor shall be pending or threatened by the Securities and
Exchange Commission, ("the 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 EFFECTIVE. The Registration Statement
required pursuant to Section 9 shall have become effective, and no stop order
suspending the effectiveness thereof shall have been issued and no proceedings
therefor shall be pending or threatened by the Commission.


                                       6
<PAGE>

         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 assumption and qualifications.

         8.4      TERMINATION. This Agreement may be terminated by any Purchaser
with respect to such Purchaser only if the Closing has not occurred by May 30,
2000.

         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:

                  (a)      As soon as practicable following the Execution Date
and in any event no later than ten (10) days following the Execution 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


                                       7
<PAGE>

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 in any jurisdiction in which it is not now so qualified.

                  (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


                                       8
<PAGE>

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:

                  (a)      "Selling Shareholder" 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
Shareholder from and against any losses, claims, damages or liabilities to which
such Selling Shareholder 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 Shareholder 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 Shareholder 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 Shareholder specifically for use in preparation of the Registration
Statement, or the failure of such Selling Shareholder 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 Shareholder prior
to the pertinent sale or sales by the Selling Shareholder.

         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 contained in
Section 9.1 or 9.2 hereof respecting sale of the Shares, or


                                       9
<PAGE>

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.

         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)      upon the request of any Purchaser, as soon as
practicable after available (but in the case of the Company's Annual Report to
Shareholders, within 150 days after the end of each fiscal year of the Company),
one copy of (i) its Annual Report to Shareholders (which Annual Report shall
contain financial statements audited in accordance with generally accepted


                                       10
<PAGE>

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.

         SECTION 10. REPRESENTATIVE OF TRILOBITE LAKES CORP. ON THE COMPANY'S
                     BOARD.

         As practicable after the Closing, the Board of Directors of the Company
(the "Board") will take all steps legally necessary to elect as a member of the
Board a representative designated by Trilobite Lakes Corp. ("Trilobite"), one of
the Purchasers, who is acceptable to the other members of the Board.

         After the initial Board nominee of Trilobite has been elected, a
nominee designated by Trilobite thereafter will be nominated by the Company for
election to the Board at annual meetings of the Company's stockholders or upon
resignation, death or removal of the nominee, until the earlier of (a) such time
as Trilobite declines in writing to the Company to continue to have such
representative serving on the Board, or (b) the date on which Trilobite holds
less than half of the total number of shares which Trilobite purchases in this
Agreement. After Trilobite declines to have such representative or ceases to
hold such requisite number of shares, the nominee then serving will not be
renominated for re-election unless the Board determines on its own to renominate
such individual for election.

         SECTION 11. BROKER'S FEE.

         The Company and each Purchaser (severally and not jointly) hereby
represent that 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 12. 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


                                       11
<PAGE>

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
                           1265 Harbor Bay Pkwy
                           Alameda, CA  94502
                           Attention:  President and Chief Executive Officer
                           Facsimile:  (510) 814-8505


                          with a copy so mailed to:

                           Heller Ehrman White & McAuliffe
                           525 University Avenue
                           Palo Alto, California  94301
                           Attention:  Bruce W. Jenett, 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 13. MISCELLANEOUS.

         13.1     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.

         13.2     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.

         13.3     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.

         13.4     GOVERNING LAW. Except to the extent that the Delaware General
Corporation Law shall be applicable with respect to matters relating to the
internal corporate affairs of the Company, this Agreement shall be governed by
and construed in accordance with the laws of the State of California applicable
to contracts entered into and wholly performed within the State of California by
California residents..


                                       12
<PAGE>

         13.5     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.

         13.6     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.

         13.7     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.

         13.8     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"). 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 fees, costs and necessary disbursements in addition to any
other relief to which such party may be entitled.


                                       13
<PAGE>

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/  Nancy E. Katz
                                     ----------------------------------------
                                 Name:    Nancy E. Katz
                                 Title:   President and Chief Operating Officer

                                 PURCHASER

                                 Purchaser Name: /s/ Purchaser
                                                -----------------------------

                                 By :
                                     ----------------------------------------
                                 Name:
                                      ---------------------------------------
                                 Title:
                                       --------------------------------------
                           Address:
                                   ------------------------------------------

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

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

                           Facsimile:
                                     ----------------------------------------


                                       14


<PAGE>
                                                                     Exhibit 4.2

                         CALYPTE BIOMEDICAL CORPORATION

                              BRIDGE LOAN AGREEMENT


         This Agreement is made effective as of March 2, 2000 (the "EFFECTIVE
DATE") between Calypte Biomedical Corporation, a Delaware corporation (the
"COMPANY"), and Trilobite Lakes Corp., a Delaware corporation ("LENDER").

         1.       LENDER COMMITMENT. Lender hereby commits to loan to the
Company, on an unsecured basis, under the terms and conditions hereof, up to a
total in principal amount, for all amounts so loaned, of one million dollars
($1,000,000.00), with each such loan to be evidenced by a Convertible Bridge
Promissory Note (a "BRIDGE NOTE") of the Company to Lender in the form of
EXHIBIT A attached hereto and incorporated herein by reference. The Initial
Bridge Note, as defined in Section 2(a) hereof, as well as all Additional Bridge
Notes referred to in Section 2(c) hereof, will constitute the Bridge Notes.

         2.       INITIAL DRAWDOWN AND INITIAL BRIDGE NOTE; SUBSEQUENT DRAWDOWN
REQUESTS; ADDITIONAL BRIDGE NOTES; NO REBORROWING; EQUAL RANKING OF BRIDGE
NOTES; EXTENSION OF DUE DATE OF BRIDGE NOTES; INTEREST DURING EXTENSION.

                  (a)      INITIAL DRAWDOWN AND INITIAL BRIDGE NOTE. As soon
as practicable following the execution of this agreement, Lender will loan to
the Company five hundred thousand dollars ($500,000.00) in principal amount,
as the initial drawdown by the Company from Lender pursuant to this
Agreement, receipt of which funds the Company acknowledges, in exchange for
the issuance by the Company to Lender of a Bridge Note (the "INITIAL BRIDGE
NOTE") in the form attached hereto as Exhibit A, receipt of which executed
Initial Bridge Note is acknowledged by Lender.

                  (b)      SUBSEQUENT DRAWDOWN REQUESTS. Amounts loaned to the
Company by Lender pursuant to this Agreement, beyond the initial loan by Lender
to the Company pursuant to this Agreement evidenced by the Initial Bridge Note,
will be made only in response to a written request of the Company to Lender
therefor (each such request referred to herein as a "DRAWDOWN REQUEST"). Each
Drawdown Request will (i) be given at least five (5) business days (defined as a
day when U.S. national banks are open for business) prior to the date upon which
such funds are requested, and (ii) be for a minimum of one hundred thousand
dollars ($100,000.00) or such lesser amount as is available after subtracting,
from the one million dollar ($1,000,000.00) maximum aggregate principal amount
limit set forth in Section 1 hereof, the aggregate principal amount of all
then-outstanding Bridge Notes.

                  (c)      ADDITIONAL BRIDGE NOTES. Each such additional loan
will be made under additional Convertible Promissory Notes of the Company
(the "ADDITIONAL BRIDGE NOTES") delivered by the Company, at the date of such
subsequent borrowing, to the Lender, which will be identical in form to the
Initial Bridge Note except as to the date(s) and principal amount(s) thereof,
and, as applicable, the interest rate thereof. As will be provided in the
Additional Bridge Notes, (i) the Bridge Notes will rank equally among
themselves as to all rights, (ii) all Bridge Notes will have the same due
date, which will be May 30, 2000, and (iii) the interest rate for such
Additional Bridge Notes will be 6.75%. Each such Additional Bridge Note will
be deemed subject to this Agreement upon its issuance.

<PAGE>


                  (d)      MAXIMUM TOTAL PRINCIPAL AMOUNT; NO REBORROWING. The
maximum total principal amount under all outstanding Bridge Notes, together,
will not exceed one million dollars ($1,000,000.00). No amount repaid by the
Company under any of the Bridge Notes may be reborrowed by the Company from the
Lender.

                  (e)      EQUAL RANKING OF BRIDGE NOTES. Without the express
prior written consent of Lender, (i) each of the Bridge Notes will rank equally
(PARI PASSU) among themselves as to payment, and (ii) no payment of any amount
of principal and/or interest under any Bridge Note will be paid by the Company
to Lender unless an amount prorated among the Bridge Notes in proportion to the
principal amounts of each Bridge Note is simultaneously paid by the Company to
Lender.

         3.       BRIDGE LOAN WARRANT; REGISTRATION ON FORM S-3; SEC REPORTING
AND RELATED MATTERS.

                  (a)      BRIDGE LOAN WARRANT. On the Effective Date, the
Company has issued to Lender a Warrant (the "BRIDGE LOAN WARRANT") in the form
of EXHIBIT B attached hereto and incorporated herein by reference.

                  (b)      REGISTRATION OF BRIDGE LOAN WARRANT SHARES ON FORM
S-3; TRANSFER OF BRIDGE LOAN WARRANT SHARES AFTER REGISTRATION; SEC REPORTING
AND RELATED MATTERS.

                           (i)      REGISTRATION OF BRIDGE LOAN WARRANT SHARES
ON FORM S-3. The Company will do the following:

                                    (A)      As soon as practicable following
the Effective Date, the Company will include the shares for which the Bridge
Loan Warrant is exerciseable (the "BRIDGE LOAN WARRANT Shares") in a
registration statement (the "REGISTRATION STATEMENT") which the Company will
file with the Securities and Exchange Commission (the "SEC") in connection with
a Common Stock Purchase Agreement dated as of the Effective Date (the "COMMON
STOCK PURCHASE AGREEMENT"), which agreement provides for the sale of shares of
the Company's Common Stock (the "FINANCING SHARES") to certain investors. The
Company will use its best efforts to cause such Registration Statement to be
declared effective as soon thereafter as reasonably possible.

                                    (B)      The Company will prepare and file
with the SEC (1) such amendments and supplements to the Registration Statement
and the prospectuses used in connection therewith, (2) such SEC reports and
filings required to be filed by the Company, and (3) such other filings required
by the SEC, 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 date of the closing of the Common Stock Purchase
Agreement, (b) such date as all of the Financing Shares have been resold or (c)
such time as all of the Financing Shares held by the holders thereof under the
Common Stock Purchase Agreement can be sold within a given three-month period
pursuant to Rule 144 under the Securities Act.


                                      -2-
<PAGE>

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 Lender, if the Company has 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 Statements more than twice in any twelve (12)
month period. Lender agrees that, upon receipt of any notice from the Company of
a Suspension Period, Lender will not sell any of the Bridge Loan Warrant Shares
pursuant to the Registration Statement until (1) Lender is advised in writing by
the Company that the use of the applicable prospectus may be resumed, (2) Lender
has received copies of any additional or supplemental or amended prospectus, if
applicable, and (3) Lender 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 by Lender of all or any of the Bridge Loan Warrant
Shares, the Company will furnish to Lender, with respect to the Bridge Loan
Warrant Shares which have been registered under the Registration Statements,
such number of copies of prospectuses, prospectus supplements and preliminary
prospectuses as Lender reasonably requests in conformity with the requirements
of the Securities Act of 1933, as amended (the "SECURITIES ACT").

                                    (D)      The Company will file any documents
required of the Company for normal blue sky clearance in states specified in
writing by Lender; provided, however, that the Company will not be required to
qualify to do business in any jurisdiction in which it is not now so qualified.

                                    (E)      Other than fees and expenses, if
any, of counsel or other advisers to Lender, which fees and expenses will be
borne by Lender, the Company will bear all expenses, (exclusive of any brokerage
fees, underwriting discounts and commissions) in connection with the procedures
in this Section 3(c).

                                    (F)      With a view to making available to
Lender 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 the Bridge Loan Warrant Shares to the public without
registration or pursuant to registration, the Company covenants and agrees to:
(1) 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 Bridge Loan Warrant Shares have been
resold; (2) file with the SEC in a timely manner all reports and other documents
required of the Company under the Securities Exchange Act of 1934 (the "EXCHANGE
ACT"); and (3) furnish to any Purchaser upon request, as long as the Purchaser
owns any Bridge Loan Warrant 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 Bridge
Loan Warrant Shares without registration under the Securities Act.

                           (ii)     TRANSFER OF BRIDGE LOAN WARRANT SHARES AFTER
REGISTRATION. Lender agrees that Lender will not effect any disposition of the
Bridge Loan


                                      -3-
<PAGE>

Warrant Shares that would constitute a sale within the meaning of the Securities
Act, except:

                                    (A)      pursuant to the applicable
Registration Statement, in which case Lender will submit the certificates
evidencing the Bridge Loan Warrant Shares to the Company's transfer agent,
accompanied by a separate certificate (1) in customary form as will be required
for such transfer of any of the Financing Shares under the Common Stock Purchase
Agreement, (2) executed by Lender or by an officer of, or other authorized
person designated by, Lender, and (3) to the effect that (a) the Bridge Loan
Warrant Shares have been sold in accordance with the applicable Registration
Statement and (b) the requirement of delivering a current prospectus has been
satisfied; or

                                    (B)      in a transaction exempt from
registration under the Securities Act, in which case Lender will, 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.

                           (iii)    SEC REPORTING AND RELATED MATTERS. The
Company will, at all times prior the declaration of effectiveness of the Form
S-3 covering the public resale of the Bridge Loan Warrant Shares:

                                    (A)      use its best efforts to make and
keep public information available, as those terms are understood and defined in
Rule 144, as promulgated under the Securities Act;

                                    (B)      use its best efforts to file with
the SEC in a timely manner all reports and other documents required of the
Company under the Securities Act and the Exchange Act;

                                    (C)      furnish to Lender, so long as
Lender owns any Bridge Loan Warrant Shares, forthwith upon request (1) a written
statement by the Company as to the Company's compliance with the reporting
requirements of Rule 144, the Securities Act and the Exchange Act (during such
time after the Company is subject to such reporting requirements), or as to its
qualification as a registrant whose securities may be resold pursuant to Form
S-3 (at any time it so qualifies), (2) a copy of the most recent annual or
quarterly report of the Company and such other reports and documents so filed by
the Company, and (3) such other information as may be reasonably requested in
availing Lender of any rule or regulation of the SEC which permits the selling
of any such securities without registration or pursuant to such form; and

                                    (D)      at all times during which the
Company is neither subject to the reporting requirements of Section 13 or 15(d)
of the Exchange Act, provide in written form, upon the written request of
Lender, or a prospective purchaser or securities of the Company from Lender, all
information required by Rule 144A(d)(4)(i) of the General Regulations
promulgated by the SEC under the Securities Act ("144A INFORMATION"); the
Company further agrees, upon written request, to cooperate with and assist
Lender or any member of the National Association of Securities Dealers, Inc.
system for Private Offerings Resales and Trading through Automated Linkages
("PORTAL") in applying to designate and thereafter maintaining the eligibility
of the Company's securities for trading through


                                      -4-
<PAGE>

PORTAL. The Company's obligations under this Section 3(c)(iii) will at all times
be contingent upon Lender's obtaining from a prospective purchaser an agreement
to take all reasonable precautions to safeguard the 144A Information from
disclosure to anyone other than employees of the prospective purchaser who
require access to the 144A Information for the sole purpose of evaluating its
purchase of the Company's securities.

         4.       USE OF PROCEEDS. All proceeds to the Company from the Bridge
Notes will be used by the Company only for operating capital, including regular
payments by the Company of debt of the Company to institutional or other
financial lenders to the Company incurred (a) prior to the Effective Date or (b)
after the Effective Date, in each case in the ordinary course of the Company's
business.

         5.       MISCELLANEOUS.

                  (a)      COUNTING OF TIME. Whenever days are to be counted
under this Agreement, the first day will not be counted and the last day will be
counted.

                  (b)      NOTICES. All notices, requests, consents and other
communications hereunder to any party will be deemed to be sufficient if
contained in a written instrument delivered in person, including delivery by
recognized express courier, fees prepaid, or sent by facsimile transmission or
duly sent by first class registered or certified mail, return receipt requested,
postage prepaid, in each case addressed as set forth below such party's
signature below, or to such other address as may hereinafter be designated in
writing by the recipient to the sender pursuant to this Section 4(b). All such
notices, requests, consents and other communications will be deemed to have been
received in the case of personal delivery, including delivery by express
courier, on the date of such delivery; in the case of facsimile transmission, on
the date of transmission; and in the case of mailing, on the third day after
deposit in the U.S. mail, proper postage prepaid.

                  (c)      TERMINATION. When the Company has repaid to Lender
all amounts owed to Lender under all Bridge Notes, whether by payment in cash,
or conversion to equity securities of the Company, or any combination thereof,
this Agreement will terminate automatically without the need for any other or
further signature of any party or any other action.

                  (d)      AMENDMENTS AND WAIVERS. Neither this Agreement or any
term hereof may be amended, modified or waived, except by written instrument
signed by the Company and by Lender. No course of dealing between the parties
will operate as a waiver of either party's rights under this Agreement. A waiver
on any one occasion will not be construed as a bar to or waiver of any right or
remedy on any future occasion. The Company acknowledges that the giving by
Lender of any notice or information to the Company, or the securing of any
consent by the Company, not required by the express terms hereof to be given or
secured, will not by implication constitute an amendment to or waiver or
modification of any provision hereof, or impose upon Lender any duty to give any
such notice or information or to secure any such consent on any future occasion.

                  (e)      ATTORNEYS' FEES. If either party hereto commences or
maintains any action at law or in equity (including counterclaims or
cross-complaints) against the other


                                      -5-
<PAGE>

party by reason of the breach or claimed breach of any term or provision of this
Agreement by such other party, then the prevailing party in such action will be
entitled to recover its reasonable attorney's fees and court costs incurred
therein from the other party to such action.

                  (f)      SUCCESSORS AND ASSIGNS. The provisions of this
Agreement will inure to the benefit of, and be binding on, each party's
respective successors and assigns. This Agreement is not assignable in whole or
in part by either party hereto without the prior written consent of both
parties, which will not be unreasonably withheld or delayed.

                  (g)      SEVERABILITY; ENTIRE AGREEMENT. The invalidity or
unenforceability of any term or provision of this Agreement will not affect the
validity or enforceability of any other term or provision hereof. The headings
in this Agreement are for convenience of reference only and will not alter or
otherwise affect the meaning of this Agreement. This Agreement and the Bridge
Notes, and the Exhibits hereto and thereto, together constitute the entire
agreement of the parties regarding the specific subject matter hereof and
supersede any and all prior understandings or agreements between the parties
with respect to such specific subject matter.

                  (h)      GOVERNING LAW. This Agreement will be governed by and
construed in accordance with the laws of the State of California, excluding that
body of law pertaining to conflict of laws or choice of law.

                           (i)      EXECUTION IN COUNTERPARTS. This Agreement
may be executed in counterparts, which together will constitute one instrument.

CALYPTE BIOMEDICAL CORPORATION                TRILOBITE LAKES CORP.

By:                                           By:
   ----------------------------------            -------------------------------
Name:                                         Name:
     --------------------------------              -----------------------------
Title:                                        Title:
      -------------------------------               ----------------------------
Date signed:  March __, 2000                  Date signed:  March __, 2000
Address:  Attention: President                Address:  Attention:
          1265 Harbor Bay Parkway                                 --------------
          Alameda, CA 94502
                                              ----------------------------------

                                              ----------------------------------
Fax:      (510) 814-8403                      Fax:        (___)-___-____


                                      -6-
<PAGE>

                                    EXHIBIT A

                               FORM OF BRIDGE NOTE


<PAGE>

                                    EXHIBIT B

                           FORM OF BRIDGE LOAN WARRANT

<PAGE>
                                                                     Exhibit 4.3

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "ACT"), OR UNDER THE SECURITIES LAWS OF CERTAIN
STATES. THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND
RESALE AND MAY NOT BE TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE ACT
AND THE APPLICABLE STATE SECURITIES LAWS, PURSUANT TO REGISTRATION OR EXEMPTION
THEREFROM. HOLDERS SHOULD BE AWARE THAT THEY MAY BE REQUIRED TO BEAR THE
FINANCIAL RISKS OF THIS INVESTMENT FOR AN INDEFINITE PERIOD OF TIME. THE ISSUER
OF THESE SECURITIES MAY REQUIRE AN OPINION OF COUNSEL IN FORM AND SUBSTANCE
SATISFACTORY TO THE ISSUER TO THE EFFECT THAT ANY PROPOSED TRANSFER OR RESALE IS
IN COMPLIANCE WITH THE ACT AND ANY APPLICABLE STATE SECURITIES LAWS.


                       CONVERTIBLE BRIDGE PROMISSORY NOTE


$__________.00                                  Date of Issuance:  ____________



         Subject to the terms and conditions of this Bridge Note, for good and
valuable consideration received, CALYPTE BIOMEDICAL CORPORATION, a Delaware
corporation, (the "COMPANY"), promises to pay to TRILOBITE LAKES CORP., a
Delaware corporation (the "HOLDER"), whose address is Suite 14 Silverside
Carr Executive Center, Wilmington, Delaware 19089-1375., the principal amount of
___________________dollars ($__________.00), which principal amount the Company
acknowledges as having been received by the Company from the Holder on the date
hereof, plus simple interest accrued on unpaid principal from the date of this
Bridge Note until paid, at the rate of six and seventy-five one hundredths
percent (6.75%) per year.

         This promissory note is one of a series of Convertible Bridge
Promissory Notes (collectively, the "BRIDGE NOTES") totaling (as to this Bridge
Note and such other Bridge Notes together, regardless of when issued) up to a
maximum of one million dollars ($1,000,000.00) in principal amount, which other
Bridge Notes are identical to this Bridge Note except as to the principal
amount, interest rate, and issuance date thereof, that are issued pursuant to
that certain Bridge Loan Agreement dated as of March 2, 2000, to which the
Holder and the Company are parties (the "BRIDGE AGREEMENT").

         The following is a statement of the rights of the Holder and the terms
and conditions to which this Bridge Note is subject, to which the Holder, by
acceptance of this Bridge Note by such Holder's signature below, agrees:

         1.       PAYMENT.

                  (a) OBLIGATION. The outstanding principal under this Bridge
Note and the accrued interest thereon will be due and payable on May 30, 2000,
if prior thereto this Bridge Note is not converted, pursuant to Section 2
hereof, into Financing Automatic Conversion Shares (as defined in Section 2(a)
hereof). All payments of principal and/or interest under this Bridge Note will
be made at the address of the Holder set forth above or at such other address as
is provided by the Holder to the Company in writing.

                  (b) EQUAL RANKING OF BRIDGE NOTES. Each of the Bridge Notes,
including this Bridge Note, will rank equally among themselves as to payment. No
payment of any amount of principal and/or interest under this Bridge Note will
be paid by the Company to the Holder unless an amount, prorated among all of the
Bridge Notes in proportion to the principal amount of each Bridge Note, is
simultaneously paid to the Holder with respect to the other Bridge Notes.

<PAGE>

                  (c) PREPAYMENT. The Company may prepay this Bridge Note in
whole or in part at any time without penalty. Prepayments will be applied to
accrued but unpaid interest first and then to unpaid principal. Any prepayments
made by the Company on this Bridge Note or on any of the other Bridge Notes will
be made simultaneously on this Bridge Note and on all of the other Bridge Notes
in an amount prorated among all of the Bridge Notes in proportion to the
principal amount of each Bridge Note.

         2.       CONVERSION.

                  (a)      AUTOMATIC CONVERSION.

                           (i)      CERTAIN DEFINITIONS. For purposes of this
Bridge Note, (A) the "NEXT EQUITY FINANCING" means the sale by the Company of
shares of its Common Stock to a group of subscribing investors, under a Common
Stock Purchase Agreement dated as of March 2, 2000, having an aggregate purchase
price of all such shares so issued of up to twelve million dollars
($12,000,000.00), including in such aggregate amount the amount of this Bridge
Note and of all other Bridge Notes converted at such closing, and (B) the date
of the closing of the Next Equity Financing is hereinafter referred to as the
"FINANCING AUTOMATIC CONVERSION DATE".

                           (ii)     AUTOMATIC CONVERSION. If the Financing
Automatic Conversion Date occurs prior to the date upon which payment of this
Bridge Note is due, then on the Financing Automatic Conversion Date all
outstanding principal and accrued interest under this Bridge Note (and under all
other Bridge Notes) automatically will convert (the "FINANCING AUTOMATIC
CONVERSION"), on the Financing Automatic Conversion Date, into shares of Common
Stock of the Company (the "FINANCING AUTOMATIC CONVERSION SHARES"), at the same
price and on the same terms and conditions as the shares sold in the Next Equity
Financing.

                  (b)      MECHANICS AND EFFECT OF CONVERSION. The conversion of
this Bridge Note into the Financing Automatic Conversion Shares, pursuant to
Section 2(a) hereof, will be deemed to have been made immediately at the closing
of the Next Equity Financing on the Financing Automatic Conversion Date and the
Holder will be treated for all purposes as the record holder of such Financing
Automatic Conversion Shares on the Automatic Conversion Date. Upon such
conversion of this Bridge Note, the Company will be forever released from all of
its obligations and liabilities under this Bridge Note. No fractional shares
will be issued upon any such conversion of this Bridge Note. In lieu of any
fractional share to which the Holder would otherwise be entitled, the Company
will pay the cash value of that fractional share to the Holder, as provided
herein. The Company will give prompt written notice to the Holder and to the
holder of the other Bridge Note, of the proposed Financing Automatic Conversion
Date. The Company will furnish to the Holder, a reasonable period of time before
the proposed Financing Automatic Conversion Date, all agreements and materials
supplied to investors in the Next Equity Financing who are purchasing shares in
the Next Equity Financing in an aggregate purchase price equal to or greater
than the amount of principal and accrued interest to be converted hereunder (the
"FINANCING DOCUMENTS"). The Holder will surrender this Bridge Note on or before
the Financing Automatic Conversion Date, as set forth in the Company's notice
thereof, at the principal offices of the Company or its transfer agent together
with the executed signature page(s) to the stock purchase documents and
agreements applicable to the Next Equity Financing as requested by the Company.
The Company will, as soon as practicable thereafter, issue and deliver to the
Holder (i) a certificate or certificates for the number of Financing Automatic
Conversion Shares to which such Holder is entitled, bearing such legends as may
be required by applicable state and federal securities laws in the opinion of
legal counsel of the Company, and (ii) if applicable, a check payable to the
Holder for any cash amounts payable for any fractional share resulting from the
conversion of this Bridge Note.


                                      -2-
<PAGE>

         3.       USE OF PROCEEDS. The full proceeds of this Bridge Note will be
used by the Company for operating capital (subject to the provisions of Section
4 of the Bridge Agreement).

         4.       GOVERNING LAW. This Bridge Note will be governed by and
construed in accordance with the laws of the State of California, excluding that
body of law relating to conflict of laws.

         5.       WAIVER. The Company hereby waives diligence, presentment,
demand, protest and notice of dishonor.

         6.       COLLECTION EXPENSES. If suit is brought for collection of this
Bridge Note, the Company will pay all reasonable expenses, including reasonable
fees and costs of attorneys, incurred by the Holder in connection therewith
whether or not such suit is commenced or is prosecuted to judgment.

                                           CALYPTE BIOMEDICAL CORPORATION



                                           By:
                                              ---------------------------------
                                                Name:
                                                     --------------------------
                                                Title:
                                                      -------------------------


AGREED AND ACCEPTED:

TRILOBITE LAKES CORP.

By:
   ---------------------------------
Name:
     -------------------------------
Title:
      ------------------------------
Date signed March __, 2000

                                      -3-

<PAGE>
                                                                     Exhibit 4.4

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "ACT"), OR UNDER THE SECURITIES LAWS OF CERTAIN
STATES. THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON TRANSFERABILITY AND
RESALE AND MAY NOT BE TRANSFERRED OR RESOLD EXCEPT AS PERMITTED UNDER THE ACT
AND THE APPLICABLE STATE SECURITIES LAWS. PURSUANT TO REGISTRATION OR EXEMPTION
THEREFROM. INVESTORS SHOULD BE AWARE THAT THEY MAY BE REQUIRED TO BEAR THE
FINANCIAL RISKS OF THIS INVESTMENT FOR AN INDEFINITE PERIOD OF TIME. THE ISSUER
OF THESE SECURITIES MAY REQUIRE AN OPINION OF COUNSEL IN FORM AND SUBSTANCE
SATISFACTORY TO THE ISSUER TO THE EFFECT THAT ANY PROPOSED TRANSFER OR RESALE IS
IN COMPLIANCE WITH THE ACT AND ANY APPLICABLE STATE SECURITIES LAWS.

              VOID AFTER 5:00 P.M. CALIFORNIA TIME ON MARCH 2, 2005

                   WARRANT TO PURCHASE SHARES OF COMMON STOCK
                                       OF
                         CALYPTE BIOMEDICAL CORPORATION

                 (BRIDGE LOAN WARRANT TO TRILOBITE LAKES CORP.)

                          ISSUANCE DATE: MARCH 2, 2000
TRILOBITE LAKES CORP., a Delaware corporation, as the original holder hereof,
and any person to whom the interest in this Warrant is lawfully transferred (the
original holder hereof and such transferees referred to hereinafter as the
"HOLDER"), is entitled to purchase one hundred thousand (100,000) shares (as
adjusted pursuant to Section 2 hereof) of fully paid and nonassessable Common
Stock (the "SHARES") of CALYPTE BIOMEDICAL CORPORATION, a Delaware corporation
(the "COMPANY"). This Warrant is being issued to the Holder in connection with,
and simultaneously with, the loan by the Holder to the Company of up to a total
of one million dollars ($1,000,000.00) pursuant to a Bridge Loan Agreement dated
as of the Issuance Date hereof, to which the Company, as borrower thereunder,
and the Holder, as lender thereunder, are parties (the "BRIDGE LOAN AGREEMENT").

         1.       EXERCISE OF WARRANT.

                  (a)      EXERCISE PRICE; AGGREGATE EXERCISE PRICE. The
Exercise Price at which this Warrant may be exercised will be $3.62 per share,
which exercise price per share is one hundred thirty percent (130%) of the
average closing price of the Company's Common Stock on the five (5) days prior
to, and including, the Issuance Date, as such Exercise Price may be adjusted
from time to time pursuant to Section 2 hereof. The Aggregate Exercise Price
will be the amount resulting from multiplying the Exercise Price times the
number of Shares purchased upon exercise hereof.

                  (b)      EXERCISE PERIOD. This Warrant will become
exerciseable from and after the Issuance Date. To the extent this Warrant is not
previously exercised pursuant to the terms hereof, this Warrant will expire and
be void upon and after 5:00 p.m., California time, on March 2, 2005.

                  (c)      METHOD OF EXERCISE; PAYMENT. The purchase right
represented by this Warrant may be exercised by the Holder, in whole or in part,
for up to the total number of Shares remaining available to exercise by the
delivery at the principal office of the Company of: (i) this Warrant, and (ii) a
duly executed Notice of Exercise (the "EXERCISE NOTICE") in the form attached
hereto as ANNEX I-A, if when this Warrant is exercised the shares issuable upon
such exercise are not registered for public resale under the Act, or in the form
of ANNEX I-B if when this Warrant is exercised the shares issuable upon such
exercise are registered for public resale under the Act, and (iii) the payment
to the Company of an amount in each case equal to the then-applicable Exercise
Price per share multiplied by the number of Shares then being purchased, by: (A)

<PAGE>

check made payable to the Company drawn on a United States bank and for United
States funds, and/or (B) delivery to the Company of evidence of cancellation of
indebtedness of the Company to such Holder, and/or (C) any combination thereof.

                  (d)      NET ISSUE ELECTION. In lieu of exercising this
Warrant pursuant to Section 1(c) hereof, the Holder may elect to receive,
without the payment by the Holder of any additional consideration, shares of
Common Stock of the Company equal to the value of this Warrant or any portion
hereof (the "NET EXERCISE") by the surrender of this Warrant or such portion
hereof to the Company at the principal office of the Company together with a
completed Exercise Notice with the net exercise election therein properly
initialed. Thereupon, the Company will issue to the Holder such number of fully
paid and nonassessable shares of Common Stock of the Company as is computed
using the following formula:

             X = Y (A-B)
                 -------
                    A

             where:

             X = The number of Shares to be issued to the Holder pursuant to
                 this Section 1(d).

             Y = The number of Shares covered by this Warrant in respect of
                 which the Net Exercise election is made pursuant to this
                 Section 1(d).

             A = The average of the closing prices of one share of Common
                 Stock of the Company for the five (5) days immediately
                 preceding, and not including, the date on which this Warrant
                 is so exercised, on which five days the Company's Common
                 Stock was traded on Nasdaq or such other stock exchange upon
                 which its Common Stock is then traded.

             B = The Exercise Price in effect under this Warrant at the time
                 the Net Exercise election is made pursuant to this Section
                 1(d).

         To the extent legally required, the Holder will pay in cash the par
value of any shares purchased by such Net Exercise.

                  (e)      ISSUANCE OF NEW WARRANT. In the event of any exercise
of the purchase right represented by this Warrant, certificates for the Shares
so purchased will be delivered to the Holder within ten (10) business days after
receipt of such payment and, unless this Warrant has been fully exercised or has
expired, a new Warrant representing the portion of the Shares, if any, with
respect to which this Warrant will not then have been exercised will also be
issued to the Holder within such ten (10) business day period, a "BUSINESS DAY"
being defined for purposes hereof as a day when U.S. national banks are open for
business.

         2.       ADJUSTMENTS TO WARRANT. The number and kind of securities
purchasable upon the exercise of this Warrant, and the Exercise Price, will be
subject to adjustment from time to time upon the occurrence of certain events,
as follows:

                  (a)      RECLASSIFICATION, REORGANIZATION, CONSOLIDATION OR
MERGER. In case of any reclassification of the Company's Common Stock, or any
reorganization, consolidation or merger of the Company with or into another
corporation (other than a merger or reorganization with respect to which the
Company is the continuing corporation and which does not result in any
reclassification of the Company's Common Stock), the Company, or such successor
corporation, as the case may be, will execute and deliver


                                      -2-
<PAGE>

to Holder a new warrant in substitution for this Warrant which will provide that
the Holder will have the right to exercise such new warrant and upon such
exercise to receive, in lieu of each share of Common Stock previously issuable
upon exercise of this Warrant, the number and kind of securities, money and
property receivable upon such reclassification, reorganization, consolidation or
merger by a holder of shares of Common Stock of the Company for each share of
Common Stock otherwise issuable hereunder. Such new Warrant will provide for
adjustments which will be as nearly equivalents as may be practicable to the
adjustments provided for in this Section 2 including, without limitation,
adjustments to the Exercise Price and to the number of shares issuable upon
exercise of this Warrant. The provisions of this Section 2(a) will similarly
apply to successive reclassifications, reorganizations, consolidations or
mergers.

                  (b)      SPLIT, SUBDIVISION OR COMBINATION OF SHARES. If the
Company at any time while this Warrant remains outstanding and unexpired splits,
subdivides or combines its Common Stock, the number of shares for which this
Warrant is exerciseable will thereafter be adjusted to take account of such
split, subdivision or combination, and the Exercise Price will be
proportionately decreased in the case of a split or subdivision or
proportionately increased in the case of a combination. Any adjustment under
this Section 2(b) will become effective when the split, subdivision or
combination becomes effective.

                  (c)      STOCK DIVIDENDS. If the Company at any time while
this Warrant remains outstanding and unexpired pays a dividend with respect to
its Common Stock payable in shares of its Common Stock, securities convertible
into or exchangeable for its Common Stock ("CONVERTIBLE SECURITIES"), or options
to purchase Convertible Securities or its Common Stock, as applicable
("OPTIONS"), the Exercise Price will be adjusted from and after the date of
determination of the stockholders entitled to receive such dividend or
distribution, to that price determined by multiplying the Exercise Price in
effect immediately prior to such date of determination by a fraction (i) the
numerator of which will be the total number of shares of Common Stock
outstanding immediately prior to such dividend or distribution, and (ii) the
denominator of which will be the total number of shares of Common Stock
outstanding immediately after such dividend or distribution (including shares of
Common Stock issuable upon exercise, conversion or exchange of any Options or
Convertible Securities issued as such dividend or distribution), and the number
of shares for which this Warrant will be exerciseable will also be
proportionately adjusted. If the Options or Convertible Securities issued as
such dividend or distributions by their terms provide, with the passage of time
or otherwise, for any decrease in the consideration payable to the Company, or
any increase in the number of shares issuable upon exercise, conversion or
exchange thereof (by change of rate or otherwise), the Exercise Price will, upon
any such decrease or increase becoming effective, be reduced or increased to
reflect such decrease or increase as if such decrease or increase became
effective immediately prior to the issuance of the Options or Convertible
Securities as the dividend or distribution, and the number of shares for which
this Warrant is exerciseable will also be proportionately adjusted. Any
adjustment under this Section 2(c) will become effective on the record date or,
if there is no record date, on the date of issuance.

                  (d)      ADJUSTMENT OF NUMBER OF SHARES. Upon each adjustment
in the Exercise Price pursuant to this Section 2, the number of shares issuable
upon exercise of this Warrant will be adjusted to the number obtained by
dividing the then outstanding Aggregate Exercise Price by the Exercise Price
immediately after such adjustment.

         3.       LEGENDS; TRANSFERABILITY OF WARRANT; REGISTRATION ON FORM S-3;
                  RULE 144.

                  (a)      LEGENDS. Any certificate for shares issued upon
exercise hereof prior to the registration of the shares for public resale, as
set forth in Section 3(c) hereof, will be imprinted with a legend in
substantially the form set forth in the Exercise Notice.


                                      -3-
<PAGE>

                  (b)      TRANSFERABILITY OF WARRANT. Subject to compliance
with applicable securities laws, this Warrant may be transferred in the same
manner as a negotiable instrument transferable by endorsement and delivery, by
execution and delivery of a completed Assignment Form attached hereto as Annex
II.

                  (c)      REGISTRATION ON FORM S-3; RULE 144. The resale of
shares issued upon exercise hereof will be in compliance with all applicable
securities laws. Reference is made to the provisions of Section 3(c) of the
Bridge Loan Agreement with respect thereto.

         4.       MISCELLANEOUS. No fractional shares will be issued in
connection with any exercise hereunder, but in lieu of such fractional shares
the Company will make a cash payment therefor upon the basis of the Exercise
Price then in effect. The terms and provisions of this Warrant will inure to the
benefit of, and be binding upon, the Company and the Holder and their respective
successors and assigns of the Holder and of the Company. This Warrant will be
governed by and construed under the laws of the State of California, without
regard to that body of law pertaining to conflict of laws or choice of law. The
titles of the sections and subsections of this Warrant are for convenience only
and are not to be considered in construing this Warrant.

                         CALYPTE BIOMEDICAL CORPORATION


                         By:
                            -----------------------------------
                         Name:
                              ---------------------------------
                         Title:
                               --------------------------------

WARRANT ACCEPTED AND AGREED:

TRILOBITE LAKES CORP.

By:
   ------------------------------------
Name:
     ----------------------------------
Title:
      ---------------------------------
Date signed:  March _, 2000


                                      -4-
<PAGE>

                                    ANNEX I-A

                               NOTICE OF EXERCISE

                              (BRIDGE LOAN WARRANT)

                     (USE THIS FORM IF WARRANT IS EXERCISED
              BEFORE SHARES HAVE BEEN REGISTERED FOR PUBLIC RESALE)

                              DATE: ________, _____

Calypte Biomedical Corporation

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

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

                  Re:      COMMON STOCK WARRANT NOTICE OF EXERCISE

Ladies/Gentleman:

         On this date, the undersigned ________________________________________,
as the Holder of, and as defined in, that certain Warrant (the "WARRANT") dated
as of March 2, 2000 from the Company to the original holder of such Warrant,
hereby acquires from CALYPTE BIOMEDICAL CORPORATION, a Delaware corporation (the
"COMPANY"), an aggregate of ________ shares (the "RESTRICTED SECURITIES") of the
Common Stock of the Company by exercise of the Warrant hereby for such number of
shares.

         1.       INVESTMENT INTENT. The undersigned represents and warrants
that:

                  (a)      The Restricted Securities have been acquired by the
undersigned for investment and not with a view to the sale or other distribution
thereof within the meaning of the Securities Act of 1933, as amended (the
"SECURITIES ACT"), and the undersigned has no present intention of selling or
otherwise disposing of all or any portion of the Restricted Securities.

                  (b)      The undersigned has acquired the Restricted
Securities for the undersigned's own account and no one else has any beneficial
ownership in the Restricted Securities.

         2.       RESTRICTIONS ON TRANSFER. The undersigned understands that:

                  (a)      In reliance upon the representations and warranties
set forth herein, the Restricted Securities have not been registered with the
Securities and Exchange Commission (the "SEC"), and accordingly may not be
offered, sold or otherwise transferred except in compliance with the Securities
Act (including any exemptions from registration thereunder);

                  (b)      The undersigned must bear the economic risk of the
undersigned's investment in the Restricted Securities indefinitely unless the
Restricted Securities are registered pursuant to the Securities Act or, in the
opinion of counsel in form and substance satisfactory to the Company, an
exemption from the registration requirement is available;

                  (c)      The undersigned cannot be assured that any exemption
from the registration requirement will be available should the undersigned
desire to transfer the Restricted Securities, and therefore, the undersigned may
not be able to dispose of or otherwise transfer the Restricted Securities, under
the circumstances, in the amounts, or at the time proposed by the undersigned;

<PAGE>

                  (d)      Rule 144 promulgated under the Securities Act, which
provides for certain limited, routine sales of unregistered securities, is not
presently available with respect to the Restricted Securities, and the Company
is under no obligation to furnish the information that might be necessary to
enable the undersigned to sell any of the Restricted Securities under Rule 144;
and

                  (e)      Only the Company may file a registration statement
with the SEC, and unless otherwise required to do so pursuant that certain
Investors' Rights Agreement, as may be amended from time to time, between the
Company and certain security holders of the Company dated of even date with or
after the date of the Warrant: (i) the Company is under no obligation to do so
with respect to the Restricted Securities; nor (ii) does the Company have any
obligation to file any other disclosure statement with the SEC with respect
thereto.

         3.       LEGEND AND STOP-TRANSFER ORDERS. The undersigned understands
that, if required by applicable federal securities laws at the date of issuance
of the Restricted Securities, certificates or other instruments representing any
of the Restricted Securities acquired by the undersigned will bear a legend
substantially similar to the following, in addition to any other legends
required by federal or state laws, or by any contractual agreement binding upon
the undersigned with respect to the Restricted Securities:

         THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE
         SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR UNDER THE SECURITIES
         LAWS OF CERTAIN STATES. THESE SECURITIES ARE SUBJECT TO RESTRICTIONS ON
         TRANSFERABILITY AND RESALE AND MAY NOT BE TRANSFERRED OR RESOLD EXCEPT
         AS PERMITTED UNDER THE ACT AND THE APPLICABLE STATE SECURITIES LAWS,
         PURSUANT TO REGISTRATION OR EXEMPTION THEREFROM. INVESTORS SHOULD BE
         AWARE THAT THEY MAY BE REQUIRED TO BEAR THE FINANCIAL RISKS OF THIS
         INVESTMENT FOR ANY INDEFINITE PERIOD OF TIME. THE ISSUER OF THESE
         SECURITIES MAY REQUIRE AN OPINION OF COUNSEL IN FORM AND SUBSTANCE
         SATISFACTORY TO THE ISSUER TO THE EFFECT THAT ANY PROPOSED TRANSFER OR
         RESALE IS IN COMPLIANCE WITH THE ACT AND ANY APPLICABLE STATE
         SECURITIES LAWS.

         The undersigned agrees that, to ensure and enforce compliance with the
restrictions imposed by applicable law and those referred to in the foregoing
legend, or elsewhere herein, the Company may issue appropriate "stop transfer"
instructions to its transfer agent, if any, with respect to any certificate or
other instrument representing Restricted Securities, or if the Company transfers
its own securities, that it may make appropriate notation to the same effect in
the Company's records.

         4.       REPRESENTATIONS AND WARRANTIES. The undersigned represents and
warrants that:

                  (a)      The undersigned has had access to all information
regarding the Company, its present and prospective business, assets, liabilities
and financial condition that the undersigned considers important to making the
decision to invest in the Restricted Securities. The undersigned has had ample
opportunity to ask questions of and receive answers from the Company's
representatives concerning this investment and to obtain any and all documents
requested in order to supplement or verify any of the information supplied.

                  (b)      The undersigned recognizes that the investment in the
Restricted Securities involves special and substantial risks. The undersigned
recognizes (i) the highly speculative nature of the investment, (ii) the
financial hazards involved, (iii) the lack of liquidity of the Restricted
Securities and the restrictions


                                      -2-
<PAGE>

upon transferability thereof, (iv) the qualifications and backgrounds of the
principals of the Company, and (v) the tax consequences of investment in
Restricted Securities, among other matters.

                  (c)      The undersigned is capable of evaluating the merits
and risks of an investment in the Restricted Securities and is financially
capable of bearing a total loss of this investment.

                  (d)      The undersigned either (i) has a preexisting personal
or business relationship with the Company or its principals or (ii) by reason of
the undersigned's business or financial experience, has the capacity to protect
the undersigned's own interests in connection with this transaction.

                  (e)      The offer and sale of the Restricted Securities was
not accomplished by the publication of any advertisement.

                  (f)      The undersigned's address is:
                                                        ------------------------

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

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

                  (g)      NET EXERCISE ELECTION: If applicable, the undersigned
elects to purchase the Securities by Net Exercise (as defined in the Warrant),
by INITIALING in the following space (please initial ONLY if Net Exercise
chosen): ___________.

PRINTED NAME IF INDIVIDUAL :
                            ----------------------------------------------------

- --------------------------------------------
                 Signature

Date signed:  _____________, _________
Address:
        ------------------------------------

        ------------------------------------
Social Security Number:
                       ---------------------

PRINTED NAME IF CORPORATE/PARTNERSHIP/TRUST:

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

By:
   -----------------------------------------
Name:
     ---------------------------------------
Title:
      --------------------------------------
Date signed:  _____________, _________
Address:
        ------------------------------------

- --------------------------------------------
Taxpayer Identification Number:
                               -------------


                                      -3-
<PAGE>

                                    ANNEX I-B

                               NOTICE OF EXERCISE

                              (BRIDGE LOAN WARRANT)

                     (USE THIS FORM IF WARRANT IS EXERCISED
              AFTER SHARES HAVE BEEN REGISTERED FOR PUBLIC RESALE)

                              DATE: ________, _____

Calypte Biomedical Corporation

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

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

                  Re:      COMMON STOCK WARRANT NOTICE OF EXERCISE

Ladies/Gentleman:

         On this date, the undersigned ________________________________________,
as the Holder of, and as defined in, that certain Warrant (the "WARRANT") dated
as of March 2, 2000 from the Company to the original holder of such Warrant,
hereby acquires from CALYPTE BIOMEDICAL CORPORATION, a Delaware corporation (the
"COMPANY"), an aggregate of ________ shares (the "SECURITIES") of the Common
Stock of the Company by exercise of the Warrant hereby for such number of
shares.

         NET EXERCISE ELECTION: If applicable, the undersigned elects to
purchase the Securities by Net Exercise (as defined in the Warrant), by
INITIALING in the following space (please initial ONLY if Net Exercise chosen):
___________.

PRINTED NAME IF INDIVIDUAL :
                            ----------------------------------------------------

- --------------------------------------------
                Signature
Date signed:  _____________, _________
Address:
        ------------------------------------

- --------------------------------------------
Social Security Number:
                       ---------------------

PRINTED NAME IF CORPORATE/PARTNERSHIP/TRUST:

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

By:
   -----------------------------------------
Name:
     ---------------------------------------
Title:
      --------------------------------------
Date signed:  _____________, _________
Address:
        ------------------------------------

- --------------------------------------------
Taxpayer Identification Number:
                               -------------

<PAGE>

                                    ANNEX II

                                 ASSIGNMENT FORM

                              (BRIDGE LOAN WARRANT)

                         CALYPTE BIOMEDICAL CORPORATION
                              COMMON STOCK WARRANT

  (To assign the foregoing Warrant, execute this form and supply the required
 information) (Do not use this form to exercise the Warrant to purchase shares.)

FOR VALUE RECEIVED, the foregoing Warrant for Common Stock of CALYPTE BIOMEDICAL
CORPORATION and all rights evidenced thereby are hereby assigned to:

(PLEASE PRINT NAME OF ASSIGNEE)
                                ------------------------------------------------
whose address is (PLEASE PRINT)
                                ------------------------------------------------


Date:___________________, __________

Assigning Holder's Printed Name:
                                ------------------------------------------------
Assigning Holder's SIGNATURE:
                                ------------------------------------------------
Assigning Holder's Address:
                                ------------------------------------------------


NOTE: The signature to this Assignment must correspond with the name as it
appears on the face of the assigned Warrant, without any change. Officers of
corporations and those acting in a fiduciary or other representative capacity
should file with this Assignment proper evidence of authority to assign the
foregoing Warrant.

<PAGE>
                                                                     Exhibit 5.1

                                  March 10, 2000

                                                                      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 March 10, 2000, for the purpose of registering
under the Securities Act of 1933, as amended, 4,196,000 shares of its Common
Stock, $0.001 par value (the "Shares"). The Shares are issuable pursuant to the
Common Stock Purchase Agreement, dated March 2, 2000, (the "Agreement") among
the Company and the purchasers named therein and pursuant to the Warrant to
Purchase Shares of Common Stock dated as of March 2, 2000 (the "Warrant") issued
by the Company to Trilobite Lakes Corp. ("Trilobite").

         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 March 6,
                  2000 and certified to us by the President, Chief Operating
                  Officer and 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 President,
                  Chief Operating Officer and Chief Financial Officer of the
                  Company as

<PAGE>
                                                                          Page 2

                  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 March 6, 2000 as to the number
                  of shares of Common Stock that were outstanding as of March 3,
                  2000;

         (e)      The Registration Statement;

         (f)      The Agreement.

         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 and the Warrant
were 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 Warrant and set by the Board of
Directors when authorizing the issuance of the Shares will be paid and/or
transferred.

         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 are
issued in accordance with the terms of the Agreement and the Warrant and the
resolutions authorizing their issuance; (iii) appropriate stock certificates
evidencing the Shares are executed and delivered; and (iv) all applicable
securities laws are complied with, it is our opinion that the Shares are 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

<PAGE>
                                                                          Page 3

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.


         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 AUDITORS

The Board of Directors
Calypte Biomedical Corporation:

We consent to the incorporation by reference herein of our report dated
February 5, 1999, relating to the consolidated balance sheets of Calypte
Biomedical Corporation and subsidiary (the "Company") as of December 31,
1998, and 1997, and the related consolidated statements of operations,
stockholders' equity (deficit), and cash flows for each of the years in the
three-year period ended December 31, 1998, which report appears in the
December 31, 1998, annual report on Form 10-K of Calypte Biomedical
Corporation, and to the reference to our firm under the heading "Experts" in
the prospectus.

Our report dated February 5, 1999 contains an explanatory paragraph that states
that the Company has suffered recurring losses from operations and has an
accumulated deficit, which raise substantial doubt about its ability to continue
as a going concern. The consolidated financial statements do not include any
adjustments that might result from the outcome of that uncertainty.


                                                              /s/ KPMG LLP


San Francisco, California
March 10, 2000



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