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                                                                 EXHIBIT 10.4.34
                              REVOLVING CREDIT NOTE

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                                                                  COLUMBUS, OHIO
$400,000                                                         AUGUST 31, 1999
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         FOR VALUE RECEIVED, the undersigned, NEOPROBE CORPORATION, a Delaware
corporation, whose address is 425 Metro Place North, Suite 400, Dublin, Ohio
43017 (the "Borrower"), hereby promises to pay to the order of THE PROVIDENT
BANK, an Ohio banking corporation (the "Bank"), on or before December 31, 1999
(the "Maturity Date"), the principal sum of Four Hundred Thousand Dollars
($400,000) or, if such principal is less, the aggregate unpaid principal amount
of all loans made by the Bank to the Borrower pursuant to this Revolving Credit
Note (the "Revolving Credit Commitment"), together with interest, all as
provided in Section 1 of this Note.

         SECTION 1. THE DEBT. Subject to and on the terms and conditions set
forth in this Note, the Bank shall provide loans and the Borrower shall repay
the indebtedness incurred hereunder as follows:

                  1.1. REVOLVING CREDIT LOANS. During the period from and
including the date hereof to but excluding the Maturity Date, the Bank agrees,
on the terms and conditions set forth in this Agreement, to make one or more
loans ("Revolving Credit Loans") to the Borrower in an aggregate principal
amount at any one time outstanding up to but not exceeding the greater of (a)
the Revolving Credit Commitment or (b) the Borrowing Base (as defined in Section
7.15 hereof). Subject to the terms of this Note, during such period, the
Borrower may borrow, repay and reborrow the amount of the Revolving Credit
Commitment by means of Revolving Credit Loans. The date, amount, and interest
rate of each Revolving Credit Loan made by the Bank to the Borrower, and each
payment made on account of the principal thereof, shall be recorded by the Bank
on its books and records, such recordation to constitute conclusive evidence in
the absence of manifest error of the amount of such Loans and payments.

                  1.2. BORROWING PROCEDURE. The Borrower shall give the Bank
notice not later than 10:00 a.m on the date of each Revolving Loan, specifying:

                           1.2.1.  The date of such Loan, which shall be a
Banking Day; and

                           1.2.2.  The aggregate amount of the Revolving Credit
Loan.

The proceeds of the initial Revolving Credit Loan (in the amount of $353,000)
shall be distributed to the Borrower to finance payments made by the Borrower to
vendors involved in the development of products described in Section 1.6 below.
The Borrower shall forward to the Bank proof of payment to such vendors pursuant
to Section 1.7 below. The proceeds of each subsequent Revolving Credit Loan
shall be forwarded by the Bank directly to specific vendors to pay amounts the
Borrower currently owes to such vendors. The vendors who receive proceeds of


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such Revolving Credit Loans shall be those vendors who are necessary to support
the development of products described in Section 1.6 below.

                  1.3.  PRINCIPAL. The Borrower shall pay the principal balance
of this Note to the Bank on or before the Maturity Date.

                  1.4.  INTEREST.

                           1.4.1. The Debt shall bear interest on the
outstanding principal amount, for each day at a per annum rate equal to the rate
of interest for such day publicly announced by the Bank as its prime rate (the
"Prime Rate") plus one hundred (100) basis points. The Prime Rate is not
intended to be the lowest rate of interest charged by the Bank in connection
with extensions of credit for borrowers. Interest on the Debt shall be paid by
the Borrower (a) on the last day of each calendar month, commencing September
30, 1999, (b) on the Maturity Date and (c) thereafter on demand.

                           1.4.2. All interest under this Note shall be computed
on the basis of the actual days elapsed in a year of 360 days.

                  1.5.  PREPAYMENTS; PAYMENTS.

                           1.5.1. The Borrower shall have the right to make
prepayments at any time of the principal amount of the Debt, in whole or in
part, without notice. Each prepayment shall be without premium or penalty.
Subject to the terms and provisions of this Note, the Bank will reloan to the
Borrower such amounts as have been paid and applied on the principal balance of
a Revolving Credit Loan prepaid pursuant to this Section.

                           1.5.2. The Borrower shall make all payments of
principal and interest under this Note to the Bank at its main office (or such
other location as the Bank may direct) in immediately available funds. If any
payment of principal or interest on this Note shall become due on a day other
than a Banking Day, such payment shall be due and payable upon the next
succeeding Banking Day and such extension of time shall in such case be included
in computing interest in connection with such payment. A "Banking Day" is any
day on which the main office of the Bank is open for business.

                  1.6. PURPOSE. The purpose of the Revolving Credit Loans
represented by this Note is to support the development between the Borrower and
Ethicon Endo Surgery, Inc. ("EES") by providing working capital for the
manufacture of units outlined in an EES purchase order for $1,868,000.

                  1.7. CONDITION PRECEDENT. As a condition precedent to making
the first Revolving Credit Loan hereunder, the Borrower must:

                           1.7.1.   deliver to the Bank the EES purchase order;


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                           1.7.2.   set up its operating bank accounts with the
Bank within 60 days  after EES issues the purchase order;

                           1.7.3.   proof of payment to vendors of $353,000;

                           1.7.4.   open a lockbox with the Bank within 60 days
after EES issues the purchase order for the receipt of all payments received
from EES, and direct EES to make all payments to such lockbox; and

                           1.7.5.   have all liens on the personal property of
the Borrower subject to the Security Agreement described in Section 4 below
either released or subordinated to the satisfaction of the Bank.

         SECTION 2. REPRESENTATIONS AND WARRANTIES. The execution of this Note
by the Borrower shall be deemed to constitute the Borrower's representation and
warranty to the Bank that, at the time of execution and at the time of
disbursement of each Revolving Credit Loan hereunder: (a) this Note and the
Security Agreement (as defined in Section 4 hereof) are the legal, valid and
binding obligations of the Borrower, enforceable against the Borrower in
accordance with their terms; (b) the Security Agreement creates a valid lien of
the Bank in the collateral thereof, prior to the claims of any other person or
entity; (c) the execution and delivery of this Note and the Security Agreement
by the Borrower do not and will not conflict with, violate or constitute a
default under or breach of any court or administrative order, decree or ruling,
or any law, statute, ordinance or regulation, or any agreement, indenture,
mortgage, deed of trust, guaranty, lease, note or other obligation or instrument
binding upon the Borrower or any of its respective properties or assets; and (d)
neither this Note nor any other statement, assignment, agreement, instrument or
certificate of the Borrower made or delivered pursuant to or in connection with
this Note contains any untrue statement of a material fact or omits to state a
material fact required to be stated therein, in light of the circumstances under
which they were made, or necessary to make the statements therein not
misleading.

         SECTION 3.  COVENANTS.

                  3.1. COMPLIANCE WITH LAWS. On and after the date hereof and
until the Debt shall have been repaid and discharged in full or otherwise
satisfied, the Borrower shall comply with all applicable laws.

                  3.2.  FURNISHING OF FINANCIAL STATEMENTS AND OTHER
INFORMATION.

                           3.2.1.  The Borrower shall furnish to the Bank as
soon as practicable after the end of each of the month in each fiscal year of
the Borrower, and in any event within 30 days thereafter, complete internally
prepared financial statements (the "Financial Statements") of the Borrower,
including without limitation (a) a balance sheet of the Borrower as at the end
of such month, (b) a statement of operations of the Borrower for such month and
(c) a statement of cash flows of the Borrower for such month. All such Financial
Statements shall be in reasonable detail and certified by the Treasurer or
Controller of the Borrower as having been prepared in accordance with GAAP
(except as to footnotes and subject to year-end adjustments), as being



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true, accurate, complete and correct in all material respects, and as presenting
fairly the financial position of the Borrower as at the respective date of such
balance sheet and the results of operations of the Borrower for the respective
period covered.

                           3.2.2. The Borrower shall furnish to the Bank as
soon as practicable after the end of each fiscal year of the Borrower, and in
any event within 90 days thereafter, complete audited Financial Statements of
the Borrower including without limitation (a) a balance sheet of each as at the
end of such fiscal year, (b) a statement of operations of each for such fiscal
year, (c) a statement of shareholders' equity of each for such fiscal year, and
(d) a statement of cash flows of each for such fiscal year, together with
comparative figures for the previous fiscal year, all in reasonable detail. The
balance sheets and statements shall be audited in form and substance
satisfactory to the Bank by independent certified public accountants of
recognized standing acceptable to the Bank.

                           5.2.3.  The Borrower will furnish to the Bank as
soon as practicable after the end of each calendar month, and in any event
within 15 days thereafter, an Accounts aging report in a format acceptable to
the Bank and a Borrowing Base Certificate for such month. During the occurrence
of an Event of Default, the Borrower shall be required to deliver aging
schedules, trial balances, test verifications of Accounts and other reports
reasonably requested by the Bank.

         SECTION 4. SECURITY FOR DEBT. This Note is secured by and entitled to
(a) a Security Agreement dated as of the date hereof, made by the Borrower for
the benefit of the Bank (the "Security Agreement") and (b) UCC-1 financing
statements filed with the Ohio Secretary of State and the Franklin county
Recorder, each dated as of the date hereof, as any of the above may be further
amended or modified from time to time. Nothing contained in this Note, the
Security Agreement, or in any other document or instrument made in connection
herewith, shall be deemed or construed to create a partnership,
tenancy-in-common, joint tenancy, joint venture or co-ownership by or between
the Bank and the Borrower. The Bank shall not be in any way responsible for the
debts, losses, obligations or duties of the Borrower.

         SECTION 5.  EVENTS OF DEFAULT.  The following are Events of Default:

                  5.1. The Borrower fails to make a payment of interest on the
Note when and as due.

                  5.2. The Borrower fails to pay the principal of the Note when
and as due.

                  5.3. The Borrower fails to make a payment of any fee, expense
or other amount of money (not including the principal of or interest on the
Note) owing to the Bank under this Note when and as due and such failure is not
remedied within 10 Banking Days after the due date.

                  5.4. Any representation or warranty made by the Borrower in
this Note or any information contained in the Security Agreement, any
certificate, report, financial statement or other document delivered to the Bank
by the Borrower contains any untrue statement of a material fact or omits to
state a material fact required by this Note or law to be stated therein or


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necessary to make the statements therein, in light of the circumstances under
which they were made, not misleading.

                  5.5. The Borrower fails to perform any of its obligations
under or fails to comply with any covenant contained in the Note and such
failure continues unremedied for a period of ten Banking Days.

                  5.6. Any governmental body or officer or creditor of the
Borrower seizes, takes possession of or collects (whether or not the Borrower
resists or acquiesces in such seizure, taking or collection) any property of the
Borrower by any means, including, without limitation, execution, levy,
sequestration, attachment, garnishment, replevin or self-help, unless such
seizure, taking or collection is vacated or the property is discharged within 30
days after the occurrence thereof.

                  5.7. One or more final judgments are entered against the
Borrower for the payment of money aggregating in excess of $50,000 and any one
of such judgments has been outstanding for more than 30 days from the date of
its entry and has not been discharged in full or stayed pending appeal.

                  5.8.  The Borrower:

                           5.8.1.  makes an assignment for the benefit of
creditors;

                           5.8.2.  enters into any composition, compromise or
arrangement with its creditors;

                           5.8.3.  generally does not pay its debts as such
debts become due; or

                           5.8.4.  conceals, removes, or permits to be
concealed or removed, any part of its or his property, with intent to hinder,
delay or defraud its or his creditors or any of them, or makes or suffers a
transfer of any of its property, fraudulent under the provisions of any
bankruptcy, fraudulent conveyance or similar law, or makes or suffers a transfer
of its property to or for the benefit of a creditor at a time when other
creditors similarly situated have not been paid.

                  5.9.  If:

                           5.9.1.  a trustee, receiver, agent or custodian is
appointed or authorized to take charge of any property of the Borrower for the
purpose of enforcing a lien against such property or for the purpose of
administering such property for the benefit of the Borrower's creditors; or

                           5.9.2.  an order (a) for relief against the Borrower
is granted under Title 11 of the United States Code or any similar law, (b)
appointing a receiver, trustee, agent or custodian of the Borrower or any
property of the Borrower or (c) providing for a composition,



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compromise or arrangement with the creditors of the Borrower is entered by any
court or governmental body or officer; or

                           5.9.3.  the Borrower files any pleading seeking
(whether by formal action or by the admission of the material allegations of a
pleading or otherwise) any such appointment or order; or

                           5.9.4.  (a) any action or proceeding seeking any such
appointment or order is commenced without the authority or consent of the
Borrower and (b)(i) such action or proceeding is not dismissed within 90 days
after its commencement or (ii) the Borrower does not diligently contest such
action or proceeding.

                  5.10. An Event of Default occurs under the Security Agreement.

                  5.11. Except for the events that exist on the date this Note
is executed as disclosed on Schedule 5.11 hereto, the Borrower fails to pay when
and as due the principal of or any interest on any Indebtedness (as defined
below), other than as evidenced by this Note or the Security Documents (assuming
that all required notices have been properly given and all corresponding grace
periods, if any, have elapsed without cure by the Borrower) or any other event
exists which, under the terms of any agreement or instrument other than the Note
or the Security Documents, relates to any Indebtedness becoming, or becoming
capable at such time of being declared, due and payable before it would
otherwise have been due and payable. "Indebtedness" means, for the Borrower (a)
all indebtedness or other obligations of the Borrower for borrowed money or for
the deferred purchase price of property or services (except for unsecured trade
payables incurred in the ordinary course of business on normal and reasonable
terms), (b) all indebtedness or other obligations of any other person for
borrowed money or for the deferred purchase price of property or services, the
payment or collection of which the Borrower has guaranteed (except by reason of
endorsement for deposit or collection in the ordinary course of business) or in
respect of which the Borrower is liable, contingently or otherwise, including,
without limitation, liable by way of agreement to purchase, to provide funds for
payment, to supply funds to or otherwise to invest in such other person, or
otherwise to assure a creditor against loss, (c) all indebtedness or other
obligations of any other person for borrowed money or for the deferred purchase
price of property or services secured by (or for which the holder of such
indebtedness has an existing right, contingent or otherwise, to be secured by)
any lien upon or in property (including, without limitation, accounts and
contract rights) owned by the Borrower whether or not the Borrower has assumed
or become liable for the payment of such indebtedness or other obligations, (d)
all direct or contingent obligations of the Borrower in respect of letters of
credit and (e) all lease obligations which have been or should be, in accordance
with generally accepted accounting principles, capitalized on the books of the
Borrower as lessee.

         SECTION 6.  DEFAULT REMEDIES.

                  6.1. ACCELERATION. If an Event of Default exists, the
outstanding unpaid principal balance of this Note, together with all interest
accrued hereon is immediately due and payable, without presentment, demand,
protest or notice of any kind, all of which are hereby waived.



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                  6.2. SET-OFF. Any and all moneys now or at any time hereafter
owing to the Borrower from the Bank, and all other funds on deposit in one or
more checking accounts with the Bank for the benefit of the Borrower, are hereby
pledged for the security of this and all other indebtedness from the Borrower to
the Bank or any legal holder hereof, and may, upon any demand for payment, be
paid and applied thereon whether such indebtedness be then due or to become due,
all without notice to or demand on the Borrower or any other person, all such
notices and demands being hereby expressly waived. If an Event of Default
exists, the Bank shall have the right, in addition to all other rights and
remedies available to it, to set-off against the principal of and interest on
this Note and any fees, expenses or other amounts owed to the Bank under this
Note (a) all amounts owing to the Borrower by the Bank, whether or not then due
and payable, and (b) all other funds or property of the Borrower (i) in a
deposit account (general or special) maintained with the Bank, or (ii) on
deposit with or otherwise held by or in the custody of the Bank for the
beneficial account of the Borrower, whether solely in the name of or for the
benefit of the Borrower or jointly in the name of or for the benefit of the
Borrower and any other person, all without notice to or demand on the Borrower
or any other person, all such notices and demands being hereby expressly waived.
The Bank will notify the Borrower of any such set-off promptly after its
occurrence, but the failure to give such notice shall not affect the validity of
the set-off. The Borrower hereby confirms the Bank's right of banker's set-off
(also known as banker's lien) as it applies to the Borrower as set forth above,
and nothing in this Note shall be deemed a waiver or prohibition of such right
of banker's set-off.

                  6.3. REMEDIES CUMULATIVE. The Bank may exercise the remedies
provided in the Pledge Agreement upon the occurrence of an Event of Default. No
right or remedy conferred upon the Bank by this Note or legally available to the
Bank if an Event of Default exists is intended to be exclusive of any other
right or remedy, and each such right or remedy is cumulative and in addition to
every other such right or remedy.

                  6.4. FORCE MAJEURE. The existence of an Event of Default is
not affected by the reason for its occurrence, even if the Event of Default was
not caused by a voluntary act of the Borrower or was caused by a natural
disaster or force majeure.

         SECTION 7.  MISCELLANEOUS.

                  7.1. MODIFICATIONS AND WAIVERS. No modification or waiver of
any term or provision contained in this Note and no consent to any departure by
the Borrower therefrom shall in any event be effective unless the same is in
writing and signed by the waiving party. Such waiver or consent shall be
effective only in the specific instance and for the purpose for which it is
given.

                  7.2. NOTICES. Except where specific provisions of this Note
provide for some other form of notice or require receipt as a condition of
notice, any consent, waiver, notice, demand or other instrument required or
permitted to be given under this Note shall be deemed to have been properly
received when in writing and delivered in person or sent by certified or
registered United States mail, return receipt requested, postage prepaid,
addressed, if to the Borrower: 425 Metro Place North, Suite 300, Dublin, Ohio
43017, Attention: Brent Larson; and



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if to the Bank: 10 West Broad Street, Mezzanine Level, Columbus, Ohio 43287,
Attention: Michael D. Davis. Either party may change its address for notices by
notice in the manner set forth above.

                  7.3. PARTIAL INVALIDITY. If any term or provision of this Note
or the application thereof to any person, firm or corporation or any
circumstance, shall be invalid or unenforceable, the remainder of this Note, or
the application of such term or provision to any person, firm or corporation or
any circumstances, other than those as to which it is held invalid, shall both
be unaffected thereby and each term or provision of this Note shall be valid and
be enforced to the fullest extent permitted by law.

                  7.4. NO IMPLIED RIGHTS OR WAIVERS. No notice to or demand on
the Borrower in any case shall entitle the Borrower to any other or further
notice or demand in the same, similar or other circumstances. Neither any
failure nor any delay on the part of the Bank in exercising any right, power or
privilege hereunder shall operate as a waiver thereof, nor shall a single or
partial exercise thereof preclude any other or further exercise of the same or
the exercise of any other right, power or privilege. The Borrower hereby waives
presentment, demand, notice, protest and all other demands and notices in
connection with the delivery, acceptance, performance, default or enforcement of
this Note.

                  7.5. SUCCESSORS AND ASSIGNS. This Note shall be binding upon
and inure to the benefit of the respective heirs, successors and assigns of the
Bank and the Borrower; provided that the Borrower shall have no right to assign
or transfer its rights under this Note voluntarily or by operation of law
without first obtaining the written consent of the Bank, and any attempted
assignment or transfer in the absence of such consent shall be void and of no
effect.

                  7.6. EXPENSES. All fees, costs and expenses, including
reasonable fees and expenses of outside legal counsel, incurred by the Bank in
connection with the preparation and enforcement of this Note or any other
instruments, documents, or agreements to be delivered pursuant hereto or in
connection herewith, shall be paid by the Borrower to the Bank on demand.

                  7.7. SURVIVAL OF PROVISIONS. All covenants, agreements,
representations, warranties and statements made in this Note or in any
certificate, statement, or other instrument given pursuant to this Note shall
survive the execution and delivery to the Bank of this Note and the making of
the Debt and shall continue in full force and effect so long as any obligation
of the Borrower under this Note is outstanding and unpaid.

                  7.8. CAPTIONS. The captions and section numbers appearing in
this Note are inserted only as a matter of convenience; they do not define,
limit, construe or describe the scope or intent of the provisions of this Note.

                  7.9. GOVERNING LAW. This Note shall be governed and construed
by the provisions hereof and in accordance with the laws of the State of Ohio
applicable to instruments to be performed in the State of Ohio.



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                  7.10. CONSENT. The Borrower hereby irrevocably and
unconditionally consents to submit to the exclusive jurisdiction of the courts
of the State of Ohio and of the United States of America located in the City of
Columbus, Ohio for any actions, suits or proceedings arising out of or relating
to this Note and the transactions contemplated hereby (and the Borrower agrees
not to commence any action, suit or proceeding relating thereto except in such
courts), and further agrees that service of any process, summons, notice or
document by U.S. certified or registered mail, return receipt requested, to the
address set forth in Section 7.2 shall be effective service of process for any
action, suit or proceeding brought against the Borrower in any such court. The
Borrower hereby irrevocably and unconditionally waives any objection to the
laying of venue of any action, suit or proceeding arising out of this Note, or
the transactions contemplated hereby, in the courts of the State of Ohio or the
United States of America located in the City of Columbus, Ohio, and hereby
further irrevocably and unconditionally waives and agrees not to plead or claim
in any such court that any such action, suit or proceeding brought in any such
court has been brought in an inconvenient forum.

                  7.11. JOINT PREPARATION. This Note is to be deemed to have
been prepared jointly by the Borrower and the Bank, and any uncertainty or
ambiguity existing herein shall not be interpreted against either party, but
shall be interpreted according to the rules for the interpretation of arm's
length agreements.

                  7.12. THIRD PARTIES. Nothing herein expressed or implied is
intended or shall be construed to confer upon or give any person other than the
parties hereto and their successors or assigns, any rights or remedies under or
by reason of this Note.

                  7.13. CONFESSION OF JUDGMENT. The Borrower hereby authorizes
any attorney at law to appear for the Borrower, in an action on this Note, at
any time after the same become due, as herein provided, in any court of record
in or of the State of Ohio, or elsewhere, to waive the issuing and service of
process against the Borrower and to confess judgment in favor of the holder of
the this Note or the party entitled to the benefits hereof against the Borrower
for the amount that may be due, with interest at the rate herein mentioned and
costs of suit, and to waive and release all errors in said proceedings and
judgment, and all petitions in error, and right of appeal from the judgment
rendered.

                  7.14. WAIVER OF JURY TRIAL. THE BANK AND THE BORROWER HEREBY
VOLUNTARILY, IRREVOCABLY AND UNCONDITIONALLY WAIVE ANY RIGHT TO HAVE A JURY
PARTICIPATE IN RESOLVING ANY DISPUTE, WHETHER SOUNDING IN CONTRACT, TORT, OR
OTHERWISE, BETWEEN THE BANK AND THE BORROWER ARISING OUT OF, IN CONNECTION WITH,
RELATED TO, OR INCIDENTAL TO THE RELATIONSHIP ESTABLISHED BETWEEN THE BORROWER
AND THE BANK IN CONNECTION WITH THIS NOTE, THE SECURITY DOCUMENTS, OR ANY OTHER
AGREEMENT OR DOCUMENT EXECUTED OR DELIVERED IN CONNECTION HEREWITH OR THEREWITH
OR THE TRANSACTIONS RELATED HERETO OR THERETO. THIS PROVISION IS A MATERIAL
INDUCEMENT TO THE BANK TO ENTER INTO THE FINANCING TRANSACTIONS WITH THE
BORROWER. IT SHALL NOT IN ANY WAY AFFECT, WAIVE, LIMIT, AMEND OR MODIFY THE
BANK'S ABILITY TO PURSUE ITS REMEDIES INCLUDING, BUT NOT LIMITED TO, ANY



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CONFESSION OF JUDGMENT OR COGNOVIT PROVISION CONTAINED IN THIS NOTE, THE
SECURITY DOCUMENTS OR ANY OTHER DOCUMENT RELATED HERETO OR THERETO.

                  7.15. DEFINITIONS. As used in this Note, the following terms
shall have the meanings set forth below. Additional defined terms appear
elsewhere in this Note:

                  "Account" means and includes all accounts (whether or not
earned by performance), contract rights, chattel paper, instruments, documents,
general intangibles (including, without limitation, tax refunds and tax refund
claims) and all other forms of obligations owing to the Borrower, whether
secured or unsecured, whether now existing or hereafter created, and whether or
not specifically assigned to the Bank under the Security Agreement, all
guaranties and other security therefor, all merchandise returned to or
repossessed by Borrower, and all rights of stoppage in transit and all other
rights and remedies of an unpaid vendor, lienor or secured party.

                  "Borrowing Base" means the Net Value of Eligible Accounts.

                  "Borrowing Base Certificate" means a certificate, in the form
required by the Bank, signed by a duly authorized officer of the Borrower, that
computes the Borrowing Base, together with any memo of returns and credits,
remittance report, schedule of Accounts and such other supporting documents and
materials which the Bank, in its sole discretion, may require to be delivered
with such certificate.

                  "Customer" means any Person who is obligated as an Account
debtor or other obligor on, under, or in connection with any Account.

                  "Defaulted Account" means an Account that a Customer has not
satisfied in full on or before the 91st day after the date an invoice is issued.

                  "Eligible Account" means each Account of the Borrower which,
at the time of determination, meets all the following qualifications: (a) the
Borrower has lawful and absolute title to such Account, subject only to the Lien
of the Bank given by the Security Agreement; such Lien constitutes a perfected
Lien in the Account prior to the rights of any other Person and such Account is
not subject to any other Lien whatsoever; (b) the Borrower has the full
unqualified right to grant a Lien in such Account to the Bank as security and
collateral for the Obligations; (c) the Account is evidenced by an invoice
issued to the proper Customer and is not evidenced by any instrument or chattel
paper; (d) the Account arose from the sale of goods or services by the Borrower
in the ordinary course of business, which goods or services have been shipped or
delivered to the Customer under such Account; and such sale was an absolute sale
and not on consignment, approval or a sale-and-return basis; (e) no notice of
the bankruptcy, receivership, reorganization or insolvency of the Customer has
been received by the Borrower; (f) the Account is a valid, legally enforceable
obligation of the Customer, and is not subject to any dispute, offset,
counterclaim, or other defense on the part of such Customer; (g) it is not a
Defaulted Account; (h) the terms of the Account require payment no more than 90
days from the date an invoice is issued; (i) the Customer on the Account is not
(1) the United States of America or any foreign



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government, or any department, agency or instrumentality thereof (unless the
Borrower and the Bank shall have fully complied with the Assignment of Claims
Act of 1940, as amended, or any other applicable law governing government
Accounts, with respect to such Account), (2) the Borrower, or any affiliate of
the Borrower, (3) located outside the United States or Canada, unless the sale
is secured by a letter of credit on which the Bank is the sole beneficiary and
the form, substance and issuer of which are acceptable to the Bank, or (4)
indebted to the Borrower in an amount, which when added to all other amounts
then owed to the Borrower by any affiliate of such Customer, exceeds 50% of the
amount of all then outstanding Eligible Accounts (other than EES); (j) the
Borrower is not indebted to the Customer on the Account (or any affiliate of
such Customer) for any goods provided or services rendered to the Borrower; (k)
the Account is not owing by any Customer with 50% or more of the value of its
outstanding Accounts not qualifying as Eligible Accounts; (l) the Account is an
Account representing all or part of the sales price of merchandise, insurance
and service within the meaning of Section 3(c)(5) of the Investment Company Act
of 1940, as amended; (m) a purchase of the Account would constitute a "current
transaction" within the meaning of Section 3(a)(3) of the Securities Act of
1933, as amended; (n) the Account is denominated and payable only in United
States dollars in the United States; and (o) the Bank, acting in its sole
discretion, has not notified the Borrower the Account may not be considered as
an Eligible Account.

                  "Lien" means any mortgage, deed of trust, lien, charge,
security interest (including, without limitation, a purchase money security
interest as such term is defined in Section 9-107 of the UCC) or encumbrance of
any kind upon, or pledge of, any property or asset, whether now owned or
hereafter acquired, and includes the acquisition of, or agreement to acquire,
any property or asset subject to any conditional sale agreement or other title
retention agreement, including a lease on terms tantamount thereto or on terms
otherwise substantially equivalent to a purchase.

                  "Net Value of Eligible Accounts" means 70% of the lower of the
book value or collectible value of Eligible Accounts as reflected in the
Borrower's books in accordance with GAAP, net of all credits, discounts and
allowances (including all unissued credits in the form of a competitive
allowance or otherwise).

                  "Obligations" means (a) the obligations of the Borrower to the
Bank under the Security Agreement and this Note, (b) all costs and expenses
incurred by the Bank in the collection or the enforcement of any such
obligations of the Borrower, or realization upon the Collateral, including,
without limitation, reasonable attorneys' fees and legal expenses, (c) all
future advances made by the Bank for the maintenance, protection or preservation
of the Collateral or any portion thereof, including, without limitation,
advances for storage, insurance premiums, transportation charges, and the like
and (d) all other obligations of the Borrower to the Bank, howsoever created,
arising, or evidenced, whether direct or indirect, absolute or contingent, or
now or hereafter existing or due or to become due.

                  "Person" means any individual, sole proprietorship,
partnership, joint venture, corporation, trust, unincorporated organization,
government (or any department, agency, instrumentality or political division
thereof) or any other entity.



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         This Note was executed in Columbus, Ohio as of the date first written
above.

- --------------------------------------------------------------------------------
WARNING - BY SIGNING THIS PAPER YOU GIVE UP YOUR RIGHT TO NOTICE AND COURT
TRIAL. IF YOU DO NOT PAY ON TIME A COURT JUDGMENT MAY BE TAKEN AGAINST YOU
WITHOUT YOUR PRIOR KNOWLEDGE AND THE POWERS OF A COURT CAN BE USED TO COLLECT
FROM YOU REGARDLESS OF ANY CLAIMS YOU MAY HAVE AGAINST THE CREDITOR WHETHER FOR
RETURNED GOODS, FAULTY GOODS, FAILURE ON HIS PART TO COMPLY WITH THE AGREEMENT,
OR ANY OTHER CAUSE.
- --------------------------------------------------------------------------------


                                      NEOPROBE CORPORATION


                                      By: /s/ David C. Bupp
                                         ------------------
                                      Name:  David C. Bupp
                                      Its: President and Chief Executive Officer



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