Document:

<PAGE>

                                                                     EXHIBIT 4.3

                                 AMENDMENT NO. 1
               TO AMENDED AND RESTATED INVESTORS' RIGHTS AGREEMENT

         THIS AMENDMENT NO. 1 TO AMENDED AND RESTATED INVESTORS' RIGHTS
AGREEMENT ("Amendment") is made and entered into as of August 11, 1999, by and
among SYMBION, INC., a Tennessee corporation formerly named "UniPhy Healthcare,
Inc." (the "Company"), and those Persons identified on Exhibit A attached hereto
(collectively, the "Investors" and each individually an "Investor").

                                R E C I T A L S:

         WHEREAS, the Company and the Investors are parties to that certain
Amended and Restated Investors' Rights Agreement, dated as of June 25, 1999 (the
"Investors' Rights Agreement");

         WHEREAS, the Company and certain of the Investors are parties to that
certain Securities Purchase Agreement, dated as of July 6, 1999 (the "Purchase
Agreement");

         WHEREAS, Section 1(B) of the Purchase Agreement grants an option (the
"Option") of limited duration to Richland Ventures III, L.P. ("RVIII") to
purchase up to 3,191,489 shares (the "Option Shares") of the common stock, no
par value (the "Common Stock"), of the Company, at a purchase price of $1.88 per
share;

         WHEREAS, in the event that RVIII purchases the Option Shares, the
Company and the Investors desire that RVIII obtain the rights and obligations of
an "Investor," an "ARC Key Shareholder" and an "Anti-Dilution Investor" under
the Investors' Rights Agreement;

         WHEREAS, the Company may, pursuant to Section 1(C) of the Purchase
Agreement, issue and sell up to 5,319,149 shares (the "Reserve Shares") of
Common Stock (including the Option Shares) to any person or entity (each, a
"Reserve Share Purchaser");

         WHEREAS, in the event that a Reserve Share Purchaser purchases Reserve
Shares, the Company and the Investors may desire that such Reserve Share
Purchaser have the rights and obligations of an "Investor," a "UniPhy Preferred
Shareholder," a "UniPhy Founder" or an "ARC Key Shareholder," and an
"Anti-Dilution Investor" under the Investors' Rights Agreement;

         WHEREAS, the Company may, from time to time after the date hereof,
issue and sell additional shares of Common Stock ("Additional Shares") to
various persons or entities (each, a "Subsequent Purchaser");

         WHEREAS, in the event that a Subsequent Purchaser purchases Additional
Shares, the Company and the Investors may desire that such Subsequent Purchaser
have the rights and obligations of an "Investor" and a "UniPhy Preferred
Shareholder," a "UniPhy Founder" or an "ARC Key Shareholder" under the
Investors' Rights Agreement;

         WHEREAS, the Company and the Investors desire to amend the Investors'
Rights Agreement as set forth in this Amendment, pursuant to Section 6.5 of the
Investors' Rights Agreement; and

         WHEREAS, capitalized terms used herein without definition shall have
the same

<PAGE>

meanings ascribed to such terms in the Investors' Rights Agreement.

         NOW, THEREFORE, in consideration of the foregoing and the respective
covenants and agreements contained herein, the sufficiency of which is hereby
acknowledged, the parties hereby agree and consent to the following:

                               A G R E E M E N T:

1.       RVIII Amendment. The Investors' Rights Agreement is hereby amended by
adding and appending the following as Section 7 of the Investors' Rights
Agreement:

         7.   Addition of RVIII as a Party. Notwithstanding the provisions of
         Section 6.5 or any other Section hereof, upon the occurrence of: (i)
         the exercise by Richland Ventures III, L.P. ("RVIII") of the option
         (the "Option") to purchase up to 3,191,489 shares (the "Option Shares")
         of Common Stock at a purchase price of $1.88 per share which was
         granted to RVIII in Section 1(B) of that certain Securities Purchase
         Agreement, dated as of July 6, 1999 (the "Purchase Agreement"), among
         the Company and certain purchasers identified in such agreement, and
         the purchase of Option Shares by RVIII, and (ii) the execution and
         delivery to the Company by RVIII of a counterpart of this Amended and
         Restated Agreement (as then amended), adopting and accepting the terms
         hereof, and (iii) acceptance and countersignature of such counterpart
         by the Company:

              (a) RVIII shall be a party to this Amended and Restated Agreement;
and

              (b) Exhibit A attached to this Amended and Restated Agreement
         shall be amended to add RVIII as a person identified thereon, and RVIII
         shall be, and shall be included within the definition of, an "Investor"
         for purposes of this Amended and Restated Agreement; and

              (c) Exhibit A attached to this Amended and Restated Agreement
         shall be amended to identify RVIII as an "Anti-Dilution Investor," and
         RVIII shall be, and shall be included within the definition of, an
         "Anti-Dilution Investor" for purposes of this Amended and Restated
         Agreement; and

              (d) RVIII shall be, and shall be included within the definition
         of, an "ARC Key Shareholder," for purposes of this Amended and Restated
         Agreement; and

              (e) RVIII shall have, and be entitled and subject to, all of the
         rights, benefits, duties and obligations of an "Investor," an "ARC Key
         Shareholder" and an "Anti-Dilution Investor" under this Amended and
         Restated Agreement, subject to the terms hereof.

2.       Reserve Share Purchasers Amendment. The Investors' Rights Agreement is
hereby further amended by adding and appending the following as Section 8, and
Sections 8.1 and 8.2 thereunder, of the Investors' Rights Agreement:

         8.   Addition of Reserve Share Purchasers as Parties.

                                       2
<PAGE>

              8.1 Reserve Share Purchasers. The parties hereto acknowledge and
         agree that, pursuant to Section 1(C) of the Purchase Agreement, the
         Company may issue, offer and sell up to 5,319,149 shares (the "Reserve
         Shares") of Common Stock (including the 3,191,489 Option Shares) to any
         person or entity (each, a "Reserve Share Purchaser"). Notwithstanding
         the provisions of Section 6.5 or any other Section hereof, upon the
         occurrence of: (i) the purchase from the Company by a Reserve Share
         Purchaser of Reserve Shares (but not including the purchase of Option
         Shares by RVIII, which is addressed in and governed by Section 7
         above), and (ii) the execution and delivery to the Company by such
         Reserve Share Purchaser of a counterpart of this Amended and Restated
         Agreement (as then amended), adopting and accepting the terms hereof,
         and (iii) acceptance and countersignature of such counterpart by the
         Company:

                  (a) such Reserve Share Purchaser shall be a party to this
         Amended and Restated Agreement; and

                  (b) Exhibit A attached to this Amended and Restated Agreement
         shall be amended to add such Reserve Share Purchaser as a person
         identified thereon, and such Reserve Share Purchaser shall be, and
         shall be included within the definition of, an "Investor" for purposes
         of this Amended and Restated Agreement; and

                  (c) subject to Section 8.2 below, Exhibit A attached to this
         Amended and Restated Agreement shall be amended to identify such
         Reserve Share Purchaser as an "Anti-Dilution Investor," and such
         Reserve Share Purchaser shall be, and shall be included within the
         definition of, an "Anti-Dilution Investor" for purposes of this Amended
         and Restated Agreement; and

                  (d) subject to Section 8.2 below, such Reserve Share Purchaser
         shall be, and shall be included within the definition of, either of a
         "UniPhy Preferred Shareholder," a "UniPhy Founder" or an "ARC Key
         Shareholder" (as designated by the Company pursuant to Section 8.2
         below), for purposes of this Amended and Restated Agreement; and

                  (e)   subject to Section 8.2 below, such Reserve Share
         Purchaser shall have, and shall be entitled and subject to, all of the
         rights, benefits, duties and obligations of an "Investor," a "UniPhy
         Preferred Shareholder," a "UniPhy Founder" or an "ARC Key Shareholder"
         (as designated by the Company pursuant to Section 8.2 below), and an
         "Anti-Dilution Investor" under this Amended and Restated Agreement,
         subject to the terms hereof.

              8.2 Designation as Anti-Dilution Investor and UniPhy Preferred
         Shareholder, UniPhy Founder or ARC Key Shareholder. The Company shall
         have the right, power and authority, to determine, in its discretion,
         in negotiation or agreement with one or more Reserve Share Purchasers
         or otherwise, whether or not a particular Reserve Share Purchaser shall
         (in addition to becoming a party hereto and an "Investor" hereunder) be
         identified and/or designated as an "Anti-Dilution Investor" and/or a
         "UniPhy Preferred Shareholder," "UniPhy Founder" or "ARC Key
         Shareholder" for purposes of this Amended and Restated Agreement, and

                                       3
<PAGE>

         thereby have, and be entitled and subject to, all of the rights,
         benefits, duties and obligations of such designation or identification
         under this Amended and Restated Agreement, pursuant to Sub-sections
         8.1(c), (d) and (e) above.

3.       Subsequent Purchasers Amendment. The Investors' Rights Agreement is
hereby further amended by adding and appending the following as Section 9 of the
Investors' Rights Agreement:

         9. Addition of Subsequent Purchasers as Parties. The parties hereto
         acknowledge and agree that the Company may, from time to time, offer
         and sell shares of Common Stock (such shares, "Additional Shares") in
         addition to Option Shares and Reserve Shares to one or more
         individuals, persons or entities (each, a "Subsequent Purchaser").
         Notwithstanding the provisions of Section 6.5 or any other Section
         hereof, upon the occurrence of: (i) the purchase from the Company by a
         Subsequent Purchaser of Additional Shares, and (ii) the execution and
         delivery to the Company by such Subsequent Purchaser of a counterpart
         of this Amended and Restated Agreement (as then amended), adopting and
         accepting the terms hereof, and (iii) acceptance and countersignature
         of such counterpart by the Company:

              (a) such Subsequent Purchaser shall be a party to this Amended and
         Restated Agreement; and

              (b) Exhibit A attached to this Amended and Restated Agreement
         shall be amended to add such Subsequent Purchaser as a person
         identified thereon, and such Subsequent Purchaser shall be, and shall
         be included within the definition of, an "Investor" for purposes of
         this Amended and Restated Agreement; and

              (c) such Subsequent Purchaser shall have, and shall be entitled
         and subject to, all of the rights, benefits, duties and obligations of
         an "Investor" under this Amended and Restated Agreement, subject to the
         terms hereof.

4.       Deletion of Current Provision Regarding Additional Investors. The
Investors' Rights Agreement is hereby further amended by deleting Sub-section
6.5(c) of the Investors' Rights Agreement in its entirety, which subsection
shall thereupon be void and without effect.

5.       Requisite Approval. Upon execution and delivery of this Amendment by
the Company and Investors representing the requisite percentage of Registrable
Shares set forth in Section 6.5 of the Investors' Rights Agreement, this
Amendment shall constitute and be deemed to be an amendment to and part of the
Investors' Rights Agreement.

6.       No Other Changes. Except as expressly set forth or contemplated in this
Amendment, the terms and conditions of the Investors' Rights Agreement shall
remain in place and shall not be altered, amended or changed in any manner
whatsoever, except by any further amendment to the Investors' Rights Agreement
made in accordance with the terms of the Investors' Rights Agreement, as hereby
amended.

7.       Counterparts. This Amendment may be executed in any number of
counterparts and by the different parties hereto on separate counterparts, each
of which when executed and delivered shall be deemed an original effective for
binding the parties hereto, but all of which shall together constitute one and
the same instrument.

                                       4
<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Amendment to
Amended and Restated Investors' Rights Agreement, and hereby consent to the
amendment and modification of the Investors' Rights Agreement provided herein,
as of the date first above written.

THE COMPANY:

SYMBION, INC.

By: /s/ Richard E. Francis, Jr.
    ----------------------------------------
Name: Richard E. Francis, Jr.
Title: President and Chief Executive Officer

INVESTORS:

UniPhy PREFERRED SHAREHOLDERS:

ABS Capital Partners, L.P.

/s/ ABS Partners, L.P.
--------------------------------------------
By: /s/ Frederick L. Bryant
    ----------------------------------------
Name: Frederick L. Bryant
     ---------------------------------------
Title: General Partner
       -------------------------------------

/s/ Clifford G. Adlerz
--------------------------------------------
Clifford G. Adlerz

/s/ Randy W. Cook
--------------------------------------------
Randy W. Cook

--------------------------------------------
Paul Davis

/s/ Richard E. Francis, Jr.
--------------------------------------------
Richard E. Francis, Jr.

/s/ R. Dale Kennedy
--------------------------------------------
R. Dale Kennedy

                                       5
<PAGE>

--------------------------------------------
Tod Lambert

MARTIN INVESTMENT PARTNERSHIP II

/s/ Charles N. Martin, Jr.
--------------------------------------------
Name: Charles N. Martin, Jr.
      --------------------------------------
Title:
       -------------------------------------

--------------------------------------------
Kenneth C. Mitchell

PACIFIC VENTURE GROUP, L.P.
By:      PVG Equity Partner, L.L.C.,
         its General Partner

/s/ Eve M. Kurtin
--------------------------------------------
By: Eve M. Kurtin
Title: Member

PVG ASSOCIATES, L.P.
By:      PVG Equity Partner, L.L.C.,
         its General Partner

/s/ Eve M. Kurtin
--------------------------------------------
By: Eve M. Kurtin
Title: Member

/s/ Patrick R. Rooney
--------------------------------------------
Patrick R. Rooney

/s/ Teresa F. Sparks
--------------------------------------------
Teresa F. Sparks

/s/ Gregg Stanley
--------------------------------------------
Gregg Stanley

/s/ Anthony Taparo
--------------------------------------------
Anthony Taparo

ARC KEY SHAREHOLDERS:

                                       6
<PAGE>

ARTHUR S. DEMOSS FOUNDATION

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

/s/ Jerry M. Eyler
--------------------------------------------
Jerry M. Eyler

FIRST AVENUE PARTNERS, L.P.

/s/ David M. Wilds
--------------------------------------------
Name: David M. Wilds
     ---------------------------------------
Title:
       -------------------------------------

--------------------------------------------
William H. Freeman

--------------------------------------------
J. Michael Gould

HEALTH TECH AFFILIATES, INC.

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

HLM/CB FUND, L.P.

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

                                       7

<PAGE>

HLM PARTNERS VII, L.P.

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

--------------------------------------------
W. Lawrence Hough

PIPER JAFFRAY, INC.

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

--------------------------------------------
B. Max Lauderdale

/s/ Charles N. Martin, Jr.
--------------------------------------------
Charles N. Martin, Jr.

/s/ Charles T. Neal
--------------------------------------------
Charles T. Neal

--------------------------------------------
Richard Panek

--------------------------------------------
Thomas Patten

--------------------------------------------
Keith B. Pitts

--------------------------------------------
Gary J. Prosterman

RICHLAND VENTURES II, L.P.

                                       8
<PAGE>

/s/ Jack Tyrrell
--------------------------------------------
Name: Jack Tyrrell
     ---------------------------------------
Title: Partner
       -------------------------------------

--------------------------------------------
Ann R. Schaaf

SOUTH ATLANTIC PRIVATE EQUITY FUND IV (QP), LIMITED PARTNERSHIP
         By:     South Atlantic Private Equity Partners IV, Limited Partnership,
                 its General Partner

                 /s/ Donald W. Burton
                 --------------------------------------------
                 Name: Donald W. Burton
                       --------------------------------------
                 Title: Chairman
                        -------------------------------------

SOUTH ATLANTIC PRIVATE EQUITY FUND IV, L.P.
         By:     South Atlantic Private Equity Partners IV, Limited Partnership,
                 its General Partner

                 /s/ Donald W. Burton
                 --------------------------------------------
                 Name: Donald W. Burton
                       --------------------------------------
                 Title: Chairman
                        -------------------------------------

--------------------------------------------
Cal Turner, Jr.

/s/ William V.B. Webb
--------------------------------------------
William V.B. Webb

WW TWO, L.P.

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

--------------------------------------------
James A. Webb, III

                                       9
<PAGE>

UniPhy FOUNDERS:

--------------------------------------------
Peter Davidson

/s/ Shannon W. Fiser
--------------------------------------------
Shannon W. Fiser

THE FRANCIS IRREVOCABLE TRUST, ANN FRANCIS, TRUSTEE

/s/ Richard E. Francis, Jr.
--------------------------------------------
Name: Richard E. Francis, Jr.
     ---------------------------------------
Title:
       -------------------------------------

/s/ Victor Giovanetti
--------------------------------------------
Victor Giovanetti

/s/ George M. Goodwin
--------------------------------------------
George M. Goodwin

--------------------------------------------
Marlene D. Kelley

/s/ H. Edward Kleine III
--------------------------------------------
H. Edward Kleine III

--------------------------------------------
Darrell Naish

--------------------------------------------
Richard Panek

/s/ Vickie R. Warren
--------------------------------------------
Vickie R. Warren

                                    EXHIBIT A

                              SCHEDULE OF INVESTORS

                                       10
<PAGE>

UniPhy PREFERRED SHAREHOLDERS

ABS Capital Partners, L.P.*
Clifford G. Adlerz*
Randy W. Cook*
Paul Davis*
Richard E. Francis, Jr.*
R. Dale Kennedy*
Tod Lambert
Martin Investment Partnership II*
Kenneth C. Mitchell*
Pacific Venture Group, L.P.*
PVG Associates, L.P.*
Patrick R. Rooney*
Teresa F. Sparks*
Gregg Stanley*
Anthony Taparo*

ARC KEY SHAREHOLDERS

Arthur S. Demoss Foundation*
Jerry M. Eyler*
First Avenue Partners, L.P.*
William H. Freeman
J. Michael Gould
Health Tech Affiliates, Inc.
HLM/CB Fund, L.P.*
HLM Partners VII, L.P.*
W. Lawrence Hough
Piper Jaffray, Inc.*
B. Max Lauderdale
Charles N. Martin, Jr.*
Charles T. Neal*
Thomas Patten
Keith B. Pitts
Gary J. Prosterman
Richland Ventures II, L.P.*
Ann R. Schaaf
South Atlantic Private Equity Fund IV (QP)*
South Atlantic Private Equity Fund IV, L.P.*
Cal Turner, Jr.*
William V.B. Webb*
WW Two, L.P.*
James A. Webb, III

*   ANTI-DILUTION INVESTOR

UniPhy FOUNDERS

                                       11
<PAGE>

Peter Davidson
Shannon W. Fiser
The Francis Irrevocable Trust, Ann Francis, Trustee*
Victor Giovanetti
George M. Goodwin
Marlene D. Kelley
H. Edward Kleine III
Darrell Naish
Richard Panek
Vickie R. Warren

*  ANTI-DILUTION INVESTOR

                                       12<PAGE>

                                                                     EXHIBIT 4.4

                             UNIPHY HEALTHCARE, INC.

                      AMENDED AND RESTATED VOTING AGREEMENT

         This AMENDED AND RESTATED VOTING AGREEMENT (the "Amended and Restated
Voting Agreement") is made and entered into this 25th day of June, 1999, by and
among UNIPHY HEALTHCARE, INC., a Tennessee corporation (the "Company"), and
those Persons identified on Exhibit A attached hereto (collectively, the
"Investors" and each individually an "Investor").

                                    RECITALS

         WHEREAS, those Investors so identified on Exhibit A attached hereto are
common shareholders of the Company who either (1) formerly held shares of
preferred stock of the Company (the "UniPhy Preferred Shareholders") or (2) key
employees of the Company who received founders common stock of the Company (the
"UniPhy Founders") and who are parties to the Voting Agreement, dated April 16,
1998 (the "Voting Agreement"); and

         WHEREAS, those Investors so identified on Exhibit A attached hereto are
current key shareholders (the "ARC Key Shareholders") of Ambulatory Resource
Centres, Inc., a Tennessee corporation ("ARC"), who, following the Merger (as
defined below), will become common shareholders of the Company; and

         WHEREAS, the Company, UniPhy Acquisition Sub, Inc., a Tennessee
corporation and a wholly-owned subsidiary of the Company ("UniPhy Sub"), and ARC
are parties to an Agreement and Plan of Merger, dated June 8, 1999 (the "Merger
Agreement"), whereby UniPhy Sub shall merge with and into ARC, each outstanding
share of common stock of ARC shall be converted into the right to receive 6.54
shares of common stock of the Company and ARC shall become a wholly-owned
subsidiary of the Company (the "Merger"); and

         WHEREAS, it is a condition to the closing of the Merger pursuant to the
Merger Agreement that each of the parties hereto enter into this Amended and
Restated Voting Agreement; and

         WHEREAS, each of the parties hereto shall receive a substantial benefit
from the closing of the Merger; and

         WHEREAS, the UniPhy Preferred Shareholders and the UniPhy Founders
desire to amend and restate and to supersede in its entirety the Voting
Agreement in the manner set forth herein; and

         WHEREAS, the ARC Key Shareholders desire to join and be entitled to the
rights and subject to the obligations provided in the Voting Agreement, as
amended and restated in this Amended and Restated Voting Agreement.

<PAGE>

         NOW, THEREFORE, in consideration of the premises and for other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:

         1.   VOTING.

         1.1  Investor Shares. The Investors each agree to vote all shares of
voting capital stock of the Company registered in their respective names or
beneficially owned by them as of the date hereof and any and all other
securities of the Company legally or beneficially acquired by each of the
Investors after the date hereof (hereinafter collectively referred to as the
"Investor Shares"), subject to, and in accordance with, the provisions of this
Amended and Restated Voting Agreement.

         1.2  Agreement to Vote. At each election of directors during the term
of this Amended and Restated Voting Agreement, each Investor shall vote all of
such person's Investor Shares for the election as directors: (i) one
representative of Pacific Venture Group; (ii) one representative of The Martin
Investment Partnership or its subsidiary; (iii) one representative of ABS
Capital Partners, L.P.; (iv) the person from time to time designated as the
Chief Executive Officer of the Company; (v) the person from time to time
designated as the Chief Operating Officer of the Company; (vi) one (1) person
nominated by Charles N. Martin, Jr.; (vii) one (1) person nominated by Richland
Ventures II, L.P. and (viii) two (2) persons nominated by Arthur S. DeMoss
Foundation, Cal Turner, Jr., First Avenue Partners, L.P., HLM/CB Fund, L.P., HLM
Partners VII, L.P., Piper Jaffrey, Inc. South Atlantic Private Equity Fund IV
(QP), South Atlantic Private Equity Fund IV, L.P. and WW Two, L.P. Any vote
taken to remove any director elected pursuant to this Section 1.2, or to fill
any vacancy created by the resignation of a director elected pursuant to this
Section 1.2, shall also be subject to the provisions of this Section 1.2.

         1.3  Legend.

              (a) Concurrently with the execution of this Amended and Restated
Voting Agreement, there shall be imprinted or otherwise placed, on certificates
representing the Investor Shares the following restrictive legend (the
"Legend"):

                  "THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO THE
              TERMS AND CONDITIONS OF AN AMENDED AND RESTATED VOTING AGREEMENT,
              DATED JUNE 25, 1999, WHICH PLACES CERTAIN RESTRICTIONS ON THE
              VOTING OF THE SHARES REPRESENTED HEREBY. ANY PERSON ACCEPTING ANY
              INTEREST IN SUCH SHARES SHALL BE DEEMED TO AGREE TO AND SHALL
              BECOME BOUND BY ALL THE PROVISIONS OF SUCH AGREEMENT. A COPY OF
              SUCH VOTING AGREEMENT WILL BE FURNISHED TO THE RECORD HOLDER OF
              THIS CERTIFICATE WITHOUT

            Signature page to Amended and Restated Voting Agreement

<PAGE>

              CHARGE UPON WRITTEN REQUEST TO THE COMPANY AT ITS PRINCIPAL PLACE
              OF BUSINESS."

              (b) The Company agrees that, during the term of this Amended and
Restated Voting Agreement, it will not remove, and will not permit to be removed
(upon registration of transfer, reissuance or otherwise), the Legend from any
such certificate and will place or cause to be placed the Legend on any new
certificate issued to represent Investor Shares theretofore represented by a
certificate carrying the Legend.

         1.4  Successors. The provisions of this Amended and Restated Voting
Agreement shall be binding upon the successors in interest to any of the
Investor Shares. The Company shall not permit the transfer of any of the
Investor Shares on its books or issue a new certificate representing any of the
Investor Shares unless and until the person to whom such security is to be
transferred shall have executed a written Agreement, pursuant to which such
person becomes a party to this Agreement or otherwise agrees to be bound by all
the provisions hereof as if such person were an Investor, as applicable.

         1.5  Other Rights. Except as provided by this Amended and Restated
Voting Agreement, each Investor shall exercise the full rights of a shareholder
with respect to the Investor Shares, respectively.

         1.6  Termination. This Amended and Restated Voting Agreement shall
terminate in its entirety on the earlier of (a) ten years following the date of
this Agreement or (b) the date of the closing of a firmly underwritten public
offering of the common stock of the Company pursuant to an effective
registration statement under the Securities Act of 1933, as amended, at a price
per share of not less than $7.00 per share (as adjusted for any stock dividends,
combinations or splits with respect to such shares effected after the date of
this Amended and Restated Voting Agreement) and aggregate gross proceeds of not
less than $20,000,000.

         2.   MISCELLANEOUS.

         2.1  Specific Performance. The parties hereto hereby declare that it is
impossible to measure in money the damages which will accrue to a party hereto
or to their heirs, personal representatives, or assigns by reason of a failure
to perform any of the obligations under this Amended and Restated Voting
Agreement and agree that the terms of this Amended and Restated Voting Agreement
shall be specifically enforceable. If any party hereto or his heirs, personal
representatives, or assigns institutes any action or proceeding to specifically
enforce the provisions hereof, any person against whom such action or proceeding
is brought hereby waives the claim or defense therein that such party or such
personal representative has an adequate remedy at law, and such person shall not
offer in any such action or proceeding the claim or defense that such remedy at
law exists.

            SIGNATURE PAGE TO AMENDED AND RESTATED VOTING AGREEMENT

<PAGE>

         2.2  Governing Law. This Amended and Restated Voting Agreement, and
the rights of the parties hereto, shall be governed by and construed in
accordance with the laws of the State of California.

         2.3  Amendment. This Amended and Restated Voting Agreement may be
amended and any term hereof may be waived only by an instrument in writing
signed by the Company and the holders of at least seventy-five percent (75%) of
the Investor Shares.

         2.4  Severability. If any provision of this Amended and Restated Voting
Agreement is held to be invalid or unenforceable, the validity and
enforceability of the remaining provisions of this Amended and Restated Voting
Agreement shall not be affected thereby.

         2.5  Successors. This Amended and Restated Voting Agreement shall inure
to the benefit of and be binding upon the parties hereto and their respective
heirs, successors, assigns, administrators, executors and other legal
representatives.

         2.6  Additional Shares. In the event that subsequent to the date of
this Amended and Restated Voting Agreement any shares or other securities (other
than any shares or securities of another corporation issued to the Company's
shareholders pursuant to a plan of merger) are issued on, or in exchange for,
any of the Investor Shares by reason of any stock dividend, stock split,
consolidation of shares, reclassification or consolidation involving the
Company, such shares or securities shall be deemed to be Investor Shares for
purposes of this Amended and Restated Voting Agreement.

         2.7  Waivers. No waivers of any breach of this Amended and Restated
Voting Agreement extended by any party hereto to any other party shall be
construed as a waiver of any rights or remedies of any other party hereto or
with respect to any subsequent breach.

         2.8  Attorneys' Fees. In the event that any suit or action is
instituted to enforce any provision in this Amended and Restated Voting
Agreement, the prevailing party shall be entitled to all costs and expenses of
maintaining such suit or action, including reasonable attorneys' fees.

         2.9  Counterparts. This Amended and Restated Voting Agreement may be
executed in one or more counterparts, each of which will be deemed an original
but all of which together shall constitute one and the same agreement.

         2.10 Entire Agreement. This Amended and Restated Voting Agreement
constitutes the entire agreement among the parties hereto with respect to the
matters set forth herein, and it supersedes all prior oral or written
agreements, commitments or understandings with respect to the matters provided
for herein, including, without limitation, the Voting Agreement among the
Company and the parties named therein dated April 16, 1998.

            SIGNATURE PAGE TO AMENDED AND RESTATED VOTING AGREEMENT

<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Amended and
Restated Voting Agreement as of the date first above written.

COMPANY:

UNIPHY HEALTHCARE, INC.
/s/ Richard E. Francis, Jr.
--------------------------------------------
By: Richard E. Francis, Jr.
    ----------------------------------------
Its: President and Chief Executive Officer
     ---------------------------------------

INVESTORS:

UnIPhY PREFERRED SHAREHOLDERS:

ABS CAPITAL PARTNERS, L.P.

/s/ ABS Partners, L.P.
--------------------------------------------
By: Frederick L. Bryant
    ----------------------------------------
Title: General Partner
       -------------------------------------

/s/ Clifford G. Adlerz
--------------------------------------------
Clifford G. Adlerz

/s/ Randy W. Cook
--------------------------------------------
Randy W. Cook

/s/ Paul Davis
--------------------------------------------
Paul Davis

/s/ Richard E. Francis, Jr.
--------------------------------------------
Richard E. Francis, Jr.

/s/ R. Dale Kennedy
--------------------------------------------
R. Dale Kennedy

/s/ Tod Lambert
--------------------------------------------
Tod Lambert

            SIGNATURE PAGE TO AMENDED AND RESTATED VOTING AGREEMENT

<PAGE>

MARTIN INVESTMENT PARTNERSHIP II

/s/ Charles N. Martin, Jr.
--------------------------------------------
By: Charles N. Martin, Jr.
    ----------------------------------------
Title:
       -------------------------------------

/s/ Kenneth C. Mitchell
--------------------------------------------
Kenneth C. Mitchell

Pacific Venture Group, L.P.
By:      PVG Equity Partner, L.L.C.,
         its General Partner

/s/ Eve M. Kurtin
--------------------------------------------
By: Eve M. Kurtin
Title: Member

PVG ASSOCIATES, L.P.
By:      PVG Equity Partner, L.L.C.,
         its General Partner

/s/ Eve M. Kurtin
--------------------------------------------
By: Eve M. Kurtin
Title: Member

/s/ Patrick R. Rooney
--------------------------------------------
Patrick R. Rooney

/s/ Teresa F. Sparks
--------------------------------------------
Teresa F. Sparks

/s/ Gregg Stanley
Gregg Stanley

--------------------------------------------
Anthony Taparo

            SIGNATURE PAGE TO AMENDED AND RESTATED VOTING AGREEMENT

<PAGE>

ARC KEY SHAREHOLDERS:

ARTHUR S. DEMOSS FOUNDATION

/s/ Robert G. DeMoss
--------------------------------------------
By: Robert G. DeMoss
    ----------------------------------------
Title: President
       -------------------------------------

/s/ Jerry M. Eyler
--------------------------------------------
Jerry M. Eyler

FIRST AVENUE PARTNERS, L.P.

/s/ Front Street, LLC, General Partner
--------------------------------------------
By: /s/ David M. Wilds
    ----------------------------------------
Title: Managing Member
       -------------------------------------

/s/ William H. Freeman
--------------------------------------------
William H. Freeman

/s/ J. Michael Gould
--------------------------------------------
J. Michael Gould

HEALTH TECH AFFILIATES, INC.

/s/ Robert S. Gordon
--------------------------------------------
By: Robert S. Gordon
    ----------------------------------------
Title: Vice President
       -------------------------------------

HLM/CB Fund, L.P.

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

HLM PARTNERS VII, L.P.

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

            SIGNATURE PAGE TO AMENDED AND RESTATED VOTING AGREEMENT

<PAGE>

/s/ W. Lawrence Hough
--------------------------------------------
W. Lawrence Hough

PIPER JAFFRAY, INC.

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

/s/ B. Max Lauderdale
--------------------------------------------
B. Max Lauderdale

/s/ Charles N. Martin, Jr.
--------------------------------------------
Charles N. Martin, Jr.

/s/ Charles T. Neal
--------------------------------------------
Charles T. Neal

/s/ Thomas Patten
--------------------------------------------
Thomas Patten

/s/ Keith B. Pitts
--------------------------------------------
Keith B. Pitts

/s/ Gary J. Prosterman
--------------------------------------------
Gary J. Prosterman

RICHLAND VENTURES II, L.P.

/s/ Jack Tyrrell
--------------------------------------------
By: Jack Tyrrell
    ----------------------------------------
Title: Managing Partner
       -------------------------------------

/s/ Ann R. Schaaf
--------------------------------------------
Ann R. Schaaf

            SIGNATURE PAGE TO AMENDED AND RESTATED VOTING AGREEMENT

<PAGE>

SOUTH ATLANTIC PRIVATE EQUITY FUND IV (QP), LIMITED PARTNERSHIP
         By:     South Atlantic Private Equity Partners IV, Limited Partnership,
                 its general partner

                 /s/ Donald W. Burton
                 --------------------------------------------
                 By: Donald W. Burton
                     ----------------------------------------
                 Title: Partner
                        -------------------------------------

SOUTH ATLANTIC PRIVATE EQUITY FUND IV, L.P.
         By:     South Atlantic Private Equity Partners IV, Limited Partnership,
                 its general partner

                 /s/ Donald W. Burton
                 --------------------------------------------
                 By: Donald W. Burton
                     ----------------------------------------
                 Title: Partner
                        -------------------------------------

/s/ Cal Turner, Jr.
--------------------------------------------
Cal Turner, Jr.

/w/ William V.B. Webb
--------------------------------------------
William V.B. Webb

WW TWO, L.P.

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

/s/ James A. Webb, III
--------------------------------------------
James A. Webb, III

UnIPhY FOUNDERS:

--------------------------------------------
Peter Davidson

--------------------------------------------
Shannon W. Fiser

            SIGNATURE PAGE TO AMENDED AND RESTATED VOTING AGREEMENT

<PAGE>

THE FRANCIS IRREVOCABLE TRUST, ANN FRANCIS, TRUSTEE

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

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

--------------------------------------------
Victor Giovanetti

--------------------------------------------
George M. Goodwin

--------------------------------------------
Marlene D. Kelley

--------------------------------------------
H. Edward Kleine III

--------------------------------------------
Darrell Naish

--------------------------------------------
Richard Panek

--------------------------------------------
Vickie R. Warren

            SIGNATURE PAGE TO AMENDED AND RESTATED VOTING AGREEMENT
<PAGE>

                                    EXHIBIT A

                                LIST OF INVESTORS

UNIPHY PREFERRED SHAREHOLDERS

ABS Capital Partners, L.P.
Clifford G. Adlerz
Randy W. Cook
Paul Davis
Richard E. Francis, Jr.
R. Dale Kennedy
Tod Lambert
Martin Investment Partnership II
Kenneth C. Mitchell
Pacific Venture Group, L.P.
PVG Associates, L.P.
Patrick R. Rooney
Teresa F. Sparks
Gregg Stanley
Anthony Taparo

ARC KEY SHAREHOLDERS

Arthur S. Demoss Foundation
Jerry M. Eyler
First Avenue Partners, L.P.
William H. Freeman
J. Michael Gould
Health Tech Affiliates, Inc.
HLM/CB Fund, L.P.
HLM Partners VII, L.P.
W. Lawrence Hough
Piper Jaffray, Inc.
B. Max Lauderdale
Charles N. Martin, Jr.
Charles T. Neal
Thomas Patten
Keith B. Pitts
Gary J. Prosterman
Richland Ventures II, L.P.
Ann R. Schaaf
South Atlantic Private Equity Fund IV (QP)
South Atlantic Private Equity Fund IV, L.P.
Cal Turner, Jr.
William V.B. Webb

<PAGE>

WW Two, L.P.
James A. Webb, III

UnIPhY FOUNDERS

Peter Davidson
Shannon W. Fiser
The Francis Irrevocable Trust, Ann Francis, Trustee
Victor Giovanetti
George M. Goodwin
Marlene D. Kelley
H. Edward Kleine III
Darrell Naish
Richard Panek
Vickie R. Warren

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