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                                                                    EXHIBIT 10.1

                                VOTING AGREEMENT

      This Voting Agreement (the "Agreement") is made and entered into as of May
12, 2004, between RITA Medical Systems, Inc., a Delaware corporation ("Parent"),
Horizon Medical Products, Inc., a Georgia corporation (the "Company"), and the
undersigned shareholder of the Company ("Holder").

                                    RECITALS

      Pursuant to an Agreement and Plan of Merger dated as of May 12, 2004 (the
"Merger Agreement") by and among Parent, Hornet Acquisition Corp. a Delaware
corporation and wholly-owned subsidiary of Parent ("Merger Sub"), and the
Company, Merger Sub is merging with and into the Company (the "Merger") and the
Company, as the surviving corporation of the Merger, will thereby become a
wholly-owned subsidiary of Parent. Concurrently with the execution and delivery
of the Merger Agreement and as a condition and inducement to Parent and Merger
Sub to enter into the Merger Agreement, Parent has required that Holder enter
into this Agreement. The Holder is the record and beneficial owner of such
number of shares of the outstanding Common Stock, $0.001 par value per share, of
the Company as is indicated beneath Holder's signature on the last page of this
Agreement (the "Shares").

                                    AGREEMENT

      The parties agree as follows:

      1. AGREEMENT TO RETAIN SHARES.

            (a) TRANSFER AND ENCUMBRANCE. (1) Except as contemplated by the
Merger Agreement, and except as provided in Section 1(b) below, during the
period beginning on the date hereof and ending on the earlier to occur of (i)
the Effective Time (as defined in the Merger Agreement), and (ii) the Expiration
Date (as defined below), Holder agrees not to, directly or indirectly, transfer
(except as may be specifically required by court order), sell, exchange, tender,
pledge, assign, contribute to the capital of any entity, hypothecate or
otherwise dispose of (including by merger, consolidation or otherwise by
operation of law) or encumber the Shares or any New Shares (as defined below),
or to, directly or indirectly, make any offer or agreement relating thereto, (2)
Holder agrees not to, directly or indirectly, grant any proxies or powers of
attorney, deposit any of such Holder's Shares into a voting trust or enter into
a voting agreement with respect to any of such Holder's Shares, or enter into
any agreement or arrangement providing for any of the actions described in this
clause (2) and (3) Holder agrees not to, directly or indirectly, take any action
that could reasonably be expected to have the effect of preventing or disabling
Holder from performing Holder's obligations under this Agreement at any time
prior to the earlier to occur of (i) the Effective Time, and (ii) the Expiration
Date. As used herein, the term "Expiration Date" shall mean the earlier to occur
of (i) the date of termination of the Merger Agreement in accordance with the
terms and provisions thereof and (ii) the date on which the Company's Board of
Directors withdraws or modifies in a manner adverse to Parent or Merger Sub the
Company Recommendation (as defined in the Merger Agreement) in accordance with
the requirements of the second sentence of Section 4.3(e) of the Merger
Agreement.

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            (b) PERMITTED TRANSFERS. Section 1(a) shall not prohibit a transfer
of Shares or New Shares by Holder (i) in accordance with the provisions of Rule
144 applicable to Holder, (ii) if Holder is an individual (A) to any member of
Holder's immediate family, or to a trust for the benefit of Holder or any member
of Holder's immediate family, or (B) upon the death of Holder, or (iii) if
Holder is a partnership or limited liability company, to one or more partners or
members of Holder or to an affiliated Person under common control with Holder;
provided, however, that a transfer referred to in clauses (ii) and (iii) of this
sentence shall be permitted only if, as a precondition to such transfer, the
transferee agrees in writing to be bound by all of the terms of this Agreement.

            (c) NEW SHARES. Holder agrees that any shares of capital stock of
the Company that Holder purchases or with respect to which Holder otherwise
acquires record or beneficial ownership after the date of this Agreement and
prior to the earlier to occur of (i) the Effective Time and (ii) the Expiration
Date ("New Shares") shall be subject to the terms and conditions of this
Agreement to the same extent as if they constituted Shares. Holder further
agrees that any shares of capital stock of Parent that Holder purchases or with
respect to which Holder otherwise acquires record or beneficial ownership after
the date of this Agreement and prior to the earlier to occur of (i) the record
date for Parent's 2005 annual meeting of stockholders and (ii) the Expiration
Date (including without limitation shares of capital stock of Parent acquired by
Holder as a result of the Merger) shall be subject to the terms and conditions
of Section 2(b) of this Agreement.

            (d) STOP TRANSFER. From and after the date of this Agreement through
the term of this Agreement, the Company will not register or otherwise recognize
the transfer (book-entry or otherwise) of any Shares or any certificate or
uncertificated interest representing any of Holder's Shares, except as permitted
by, and in accordance with, Section 1(b).

      2. AGREEMENT TO VOTE SHARES.

            (a) Until the earlier to occur of (i) the Effective Time and (ii)
the Expiration Date, at every meeting of the shareholders of the Company called
with respect to any of the following, and at every adjournment thereof, and on
every action or approval by written consent of the shareholders of the Company
with respect to any of the following, Holder shall vote or consent the Shares
and any New Shares (i) in favor of approval of the Merger Agreement and the
Merger and (ii) against any proposal for any recapitalization, merger, sale of
assets or other business combination (other than the Merger) between the Company
and any person or entity other than Parent or any other action or agreement that
could reasonably be expected to result in a breach of any covenant,
representation or warranty or any other obligation or agreement of the Company
under the Merger Agreement or Holder under this Agreement or which could
reasonably be expected to result in any of the conditions to the Company's
obligations under the Merger Agreement not being fulfilled. This Agreement is
intended to bind Holder as a shareholder of the Company only with respect to the
specific matters set forth herein. Except as set forth in clauses (i) and (ii)
of this Section 2, Holder shall not be restricted from voting in favor of,
against or abstaining with respect to any other matter presented to the
shareholders of the Company.

                                       2
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            (b) At each of the 2004 and 2005 annual meeting of stockholders of
Parent, and at any adjournment or postponement of either such meeting, Holder
shall vote all shares of capital stock of Parent owned beneficially or of record
by Holder as of the record date for each such annual meeting in favor of the
election of the nominees for director recommended for election by the Board of
Directors of Parent; provided, however, that Holder shall have no obligation
under this Section 2(b) in the event that the Expiration Date occurs prior to
either such annual meeting of stockholders; provided further, that Holder shall
have no obligation under this Section 2(b) with respect to the 2005 annual
meeting of stockholders of Parent if (i) the individual designated by the
Company pursuant to section 5.17(a) of the Merger Agreement to serve as a Class
II director of Parent is willing, able and qualified to serve as a director of
Parent and is not one of the nominees the Board of Directors of Parent
recommends for election at the 2005 annual meeting of stockholders of Parent or
(ii) Parent's compensation policy with respect to non-employee directors is
modified in any material respect prior to the 2005 annual meeting of
stockholders of Parent. Notwithstanding the foregoing, nothing in this
Agreement, including without limitation this Section 2(b), shall restrict
Holder's ability to sell, transfer or otherwise dispose of shares of the capital
stock of Parent following the Effective Time, and no transferee of shares of the
capital stock of Parent beneficially owned by Holder shall have any obligation
under this Agreement after the Effective Time.

      3. IRREVOCABLE PROXY. Concurrently with the execution of this Agreement,
Holder agrees to deliver to Parent a proxy in the form attached hereto as
Exhibit A (the "Proxy"), which shall be irrevocable to the extent provided in
the Georgia Business Corporation Code covering the Shares and New Shares.

      4. REPRESENTATIONS, WARRANTIES AND COVENANTS OF HOLDER. Holder hereby
represents, warrants and covenants to Parent that Holder (i) is the record and
beneficial owner of the Shares, which, at the date of this Agreement and at all
times up until the earlier to occur of (A) the Effective Time, and (B) the
Expiration Date, will be free and clear of any liens, claims, options, charges
or other encumbrances, and (ii) does not own of record or beneficially any
shares of capital stock of the Company other than the Shares (excluding shares
as to which Holder currently disclaims beneficial ownership in accordance with
applicable law). Holder has the legal capacity, power and authority to enter
into and perform all of Holder's under this Agreement (including under the
Proxy). This Agreement (including the Proxy) has been duly and validly executed
and delivered by Holder and constitutes a valid and binding agreement of Holder,
enforceable against Holder in accordance with its terms, subject to (a) laws of
general application relating to bankruptcy, insolvency and the relief of debtors
and (b) rules of law governing specific performance, injunctive relief and other
equitable remedies. [IF HOLDER IS MARRIED AND HOLDER'S SHARES CONSTITUTE
COMMUNITY PROPERTY, THIS AGREEMENT (INCLUDING THE PROXY) HAS BEEN DULY
AUTHORIZED, EXECUTED AND DELIVERED BY, AND CONSTITUTES A VALID AND BINDING
AGREEMENT OF, HOLDER'S SPOUSE, ENFORCEABLE AGAINST SUCH PERSON IN ACCORDANCE
WITH ITS TERMS.] [DELETE IF INAPPLICABLE.]

      5. ADDITIONAL DOCUMENTS. Holder hereby covenants and agrees to execute and
deliver any additional documents reasonably necessary to carry out the purpose
and intent of this Agreement.

                                       3
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      6. CONSENT AND WAIVER. Holder hereby gives any consents or waivers that
are reasonably required for the consummation of the Merger under the terms of
any agreement to which Holder is a party or pursuant to any rights Holder may
have.

      7. TERMINATION. This Agreement and the Proxy delivered in connection
herewith shall terminate and shall have no further force or effect as of the
earlier to occur of (i) the Expiration Date and (ii) the date following the date
of the 2005 annual meeting of stockholders of Parent, including any adjournment
or postponement thereof.

      8. FIDUCIARY DUTIES. Notwithstanding anything in this Agreement to the
contrary: (i) Holder makes no agreement or understanding herein in any capacity
other than in Holder's capacity as a record holder and beneficial owner of the
Shares, (ii) nothing in this Agreement shall be construed to limit or affect any
action or inaction by Holder, or any officer, partner, member or employee, as
applicable, of Holder, serving on the Company's Board of Directors acting in
such person's capacity as a director or fiduciary of the Company, and (iii)
Holder shall have no liability to Parent, Merger Sub or any of their respective
affiliates under this Agreement as a result of any action or inaction by Holder,
or any officer, partner, member or employee, as applicable, of Holder, serving
on the Company's Board of Directors acting in such person's capacity as a
director or fiduciary of the Company.

      9. MISCELLANEOUS.

            (a) AMENDMENTS AND WAIVERS. Any term of this Agreement may be
amended or waived with the written consent of the parties or their respective
successors and assigns. Any amendment or waiver effected in accordance with this
Section 9(a) shall be binding upon the parties and their respective successors
and assigns.

            (b) GOVERNING LAW. This Agreement and all acts and transactions
pursuant hereto and the rights and obligations of the parties hereto shall be
governed, construed and interpreted in accordance with the laws of Delaware,
without giving effect to principles of conflicts of law.

            (c) COUNTERPARTS. This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original and all of which
together shall constitute one instrument.

            (d) TITLES AND SUBTITLES. The titles and subtitles used in this
Agreement are used for convenience only and are not to be considered in
construing or interpreting this Agreement.

            (e) NOTICES. Any notice required or permitted by this Agreement
shall be in writing and shall be deemed sufficient upon receipt, when delivered
personally or by courier, overnight delivery service or confirmed facsimile, or
72 hours after being deposited in the regular mail as certified or registered
mail (airmail if sent internationally) with postage prepaid, if such notice is
addressed to the party to be notified at such party's address or facsimile
number as set forth below, or as subsequently modified by written notice.

                                       4
<PAGE>

            (f) SEVERABILITY. If one or more provisions of this Agreement are
held to be unenforceable under applicable law, the parties agree to renegotiate
such provision in good faith, in order to maintain the economic position enjoyed
by each party as close as possible to that under the provision rendered
unenforceable. In the event that the parties cannot reach a mutually agreeable
and enforceable replacement for such provision, then (i) such provision shall be
excluded from this Agreement, (ii) the balance of the Agreement shall be
interpreted as if such provision were so excluded and (iii) the balance of the
Agreement shall be enforceable in accordance with its terms.

            (g) SPECIFIC PERFORMANCE. Each of the parties hereto recognizes and
acknowledges that a breach of any covenants or agreements contained in this
Agreement will cause Parent and Merger Sub to sustain damages for which they
would not have an adequate remedy at law for money damages, and therefore each
of the parties hereto agrees that in the event of any such breach Parent shall
be entitled to the remedy of specific performance of such covenants and
agreements and injunctive and other equitable relief in addition to any other
remedy to which they may be entitled, at law or in equity.

                            [SIGNATURE PAGE FOLLOWS]

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      The parties have caused this Agreement to be duly executed on the date
first above written.

                                     PARENT

                                     By: _______________________________________
                                     Name: _____________________________________
                                     Title: ____________________________________

                                     Address:  RITA Medical Systems, Inc.
                                     967 North Shoreline Blvd.
                                     Mountain View, CA  94043
                                     Attention:  Joseph DeVivo, President and
                                       Chief Executive Officer
                                     Facsimile No.:    (650) 967-1691

                                     COMPANY

                                     By: _______________________________________
                                     Name: _____________________________________
                                     Title: ____________________________________

                                     Address:  Horizon Medical Products, Inc.
                                     One Horizon Way
                                     Manchester, GA  91816
                                     Attention:  Robert Wenzel, President
                                     Facsimile No.:    (706) 846-5226

                       SIGNATURE PAGE TO VOTING AGREEMENT

<PAGE>

                                     HOLDER

                                     By: _______________________________________
                                     Name: _____________________________________
                                     Title: ____________________________________

                                     Holder's Address for Notice:

                                     ___________________________________________
                                     ___________________________________________
                                     ___________________________________________

Shares owned of record:                     Beneficially owned shares:
    Class of Shares      Number           Class of Shares          Number

                       SIGNATURE PAGE TO VOTING AGREEMENT

<PAGE>

                                    EXHIBIT A

                                IRREVOCABLE PROXY

                                TO VOTE STOCK OF

                         HORIZON MEDICAL PRODUCTS, INC.

                                       AND

                           RITA MEDICAL SYSTEMS, INC.

      The undersigned shareholder of Horizon Medical Products, Inc. a Georgia
corporation (the "Company"), hereby irrevocably (to the full extent permitted by
the Georgia Business Corporation Code) appoints the Chief Executive Officer and
Chief Financial Officer of RITA Medical Systems, Inc. a Delaware corporation
("Parent"), and each of them, as the sole and exclusive attorneys and proxies of
the undersigned, with full power of substitution and resubstitution, to vote and
exercise all voting and related rights (to the full extent that the undersigned
is entitled to do so) with respect to all of the shares of capital stock of the
Company and all of the shares of capital stock of Parent that now are or
hereafter may be owned of record or beneficially by the undersigned, and any and
all other shares or securities of the Company (collectively, the "Company
Shares") or Parent (collectively, the "Parent Shares" and together with the
Company Shares, the "Shares") issued or issuable in respect thereof on or after
the date hereof in accordance with the terms of this Proxy and that certain
Voting Agreement of even date herewith, by and among Parent, the Company and the
undersigned (the "Voting Agreement"). The shares of the capital stock of the
Company owned by the undersigned shareholder of the Company as of the date of
this Proxy are listed beneath the undersigned's signature on the final page of
this Proxy. Upon the undersigned's execution of this Proxy, any and all prior
proxies given by the undersigned with respect to any Shares are hereby revoked
and the undersigned agrees not to grant any subsequent proxies with respect to
the Shares until after the earlier to occur of (i) the Expiration Date (as
defined below) and (ii) the Effective Time (after which time the undersigned
agrees not to grant any proxy with respect to shares of the capital stock of
Parent in a manner inconsistent with this Proxy).

      This Proxy is coupled with an interest, is irrevocable (to the extent
permitted by the Georgia Business Corporation Code in the case of the capital
stock of the Company and, in the case of the capital stock of Parent, the
Delaware General Corporation Law), is granted pursuant to the Voting Agreement,
and is granted in consideration of Parent entering into that certain Agreement
and Plan of Merger, of even date herewith, by and among the Company, Parent and
Hornet Acquisition Corp., a Delaware corporation ("Merger Sub") and wholly-owned
subsidiary of Parent (the "Merger Agreement"). The Merger Agreement provides for
the merger of Merger Sub with and into the Company (the "Merger"). As used
herein, the term "Expiration Date" shall mean the earlier to occur of (i) the
date of termination of the Merger Agreement in accordance with the terms and
provisions thereof and (ii) the date on which the Company's Board of Directors
withdraws

<PAGE>

or modifies in a manner adverse to Parent or Merger Sub the Company
Recommendation (as defined in the Merger Agreement) in accordance with the
requirements of the second sentence of Section 4.3(e) of the Merger Agreement.

      The attorneys and proxies named above, and each of them, are hereby
further authorized and empowered by the undersigned, at any time prior to the
earlier to occur of (i) the Effective Time and (ii) Expiration Date, to act as
the undersigned's attorney and proxy to vote the Shares, and to exercise all
voting and other rights of the undersigned with respect to the Shares
(including, without limitation, the power to execute and deliver written
consents pursuant to the Georgia Business Corporation Code), at every annual,
special or adjourned meeting of the shareholders of the Company and in every
written consent in lieu of such meeting (i) in favor of approval of the Merger
and the Merger Agreement and (ii) against any proposal for any recapitalization,
merger, sale of assets or other business combination (other than the Merger)
between the Company and any person or entity other than Parent or any other
action or agreement that could reasonably be expected to result in a breach of
any covenant, representation or warranty or any other obligation or agreement of
the Company under the Merger Agreement or the undersigned under the Voting
Agreement or which could reasonably be expected to result in any of the
conditions to the Company's obligations under the Merger Agreement not being
fulfilled.

      The attorneys and proxies named above, and each of them, are hereby
authorized and empowered by the undersigned, at any time prior to the earlier to
occur (i) the Expiration Date and (ii) the date following the date of the 2005
annual meeting of stockholders of Parent, including any adjournment or
postponement thereof, to act as the undersigned's attorney and proxy to vote all
Parent Shares owned beneficially or of record by the undersigned as of the
record date for each annual meeting of Parent stockholders, and to exercise all
voting and other rights of the undersigned with respect to such shares
(including, without limitation, the power to execute and deliver written
consents pursuant to the Delaware General Corporation Law), at every annual
meeting of the stockholders of Parent, including any adjournment or postponement
thereof, in favor of the election of nominees to the Board of Directors of
Parent recommended for election by the Board of Directors of Parent.

      Any obligation of the undersigned hereunder shall be binding upon the
successors and assigns of the undersigned.

      This Proxy is irrevocable (with respect to the shares of capital stock of
the Company, to the extent provided in the Georgia Business Corporation Code
and, with respect to the shares of capital stock of Parent, to the extent
provided in the Delaware General Corporation Law).

                            [SIGNATURE PAGE FOLLOWS]

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Dated: May __, 2004

_____________________________________
(Signature of Holder)

_____________________________________
(Print Name of Holder)

_____________________________________
(Title of Signatory if Holder is an Entity)

Shares owned of record:                     Beneficially owned shares:
    Class of Shares        Number           Class of Shares          Number

                       SIGNATURE PAGE TO IRREVOCABLE PROXY