Document:

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                                                                   EXHIBIT 10.22

Letter Agreement dated September 12, 2000 between Registrant and Jeffrey T.
Arnold

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                           HEALTHEON/WEBMD CORPORATION
                            3399 PEACHTREE STREET NE
                             400 THE LENNOX BUILDING
                             ATLANTA, GEORGIA 30326

                               September 12, 2000

Mr. Jeffrey T. Arnold
3399 Peachtree Street NE
400 The Lennox Building
Atlanta, Georgia 30326

Dear Mr. Arnold:

                  Healtheon/WebMD Corporation (the "COMPANY") granted to you
options to acquire 500,000 shares of our common stock under the Company's 1996
Stock Plan and options to acquire 1,500,000 shares of our common stock under the
Company's 2000 Long-Term Incentive Plan (the "NEW OPTIONS"), as evidenced by the
Non-Qualified Stock Option Notice dated May 12, 2000 and August 1, 2000,
respectively, from the Company to you. We have agreed to modify certain aspects
of your New Options as reflected in the Amended and Restated Option Agreement
attached hereto as Exhibit A (the "AMENDED OPTION AGREEMENT"). Your execution of
this letter agreement is an inducement to the Company entering into the Amended
Option Agreement. In conjunction therewith, we request that you agree to become
bound by the noncompetition, nonsolicitation and confidentiality provisions set
forth on Exhibit B hereto effective upon the execution of the Amended Option
Agreement.

                  By agreeing to the terms of this letter, you confirm to us
that (i) in addition to the New Options, you currently own options to acquire
2,486,741 shares of the Company (together with the New Options, the "CURRENT
OPTIONS") and (ii) you will become bound by the noncompetition provisions
described on Exhibit B upon the execution of the Amended Option Agreement.

                  As additional consideration for your agreements set forth
herein, the Company agrees as follows:

                  1.       The provisions of Section 3(c)(ii) of the Amended
                           Option Agreement (providing for vesting in the case
                           of death, disability, termination without cause or
                           termination for good reason) apply to all of your
                           Current Options.

                  2.       In the event of the cessation of your employment with
                           the Company for any reason or the cessation of your
                           service in the officer position of Co-Chief Executive
                           Officer or Chief Executive Officer of the Company for
                           any reason, Current Options held by you to acquire
                           the Applicable Amount of shares of common stock that
                           would not otherwise be vested shall continue to vest
                           in accordance with the applicable schedule, and shall
                           otherwise be treated for purposes of the terms and
                           conditions thereof, as if you remained employed
                           through the earlier of (a) the first anniversary of
                           the last scheduled vesting date for such Current
                           Options or, (b) the material breach by you of the
                           provisions of Exhibit B to this letter

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                           agreement. For purposes of this paragraph 2., the
                           Applicable Amount shall mean 585,000 if such
                           cessation occurs on or prior to December 15, 2001,
                           351,000 if such cessation occurs after December 15,
                           2001 and on or before December 15, 2002, 234,000 if
                           such cessation occurs after December 15, 2002 but on
                           or before December 15, 2003, 117,000 if such
                           cessation occurs after December 15, 2003 but on or
                           before December 15, 2004. In the event cessation
                           occurs after December 15, 2004, this paragraph 2.
                           shall not apply. In the event that on the date of
                           such cessation, Current Options to acquire more than
                           the Applicable Amount of shares are not yet vested
                           and would not be vested as a result of such
                           cessation, you shall be entitled to select which of
                           the Current Options the vesting schedules for which
                           shall continue under this paragraph.

                  3.       You shall be entitled to exercise your Current
                           Options which become vested until the tenth
                           anniversary of the date of grant of such Current
                           Option, regardless of the date of the cessation of
                           your employment with the Company.

                  In addition to agreeing to the provisions of Exhibit B, you
agree that neither the Company's acquisition of Medical Manager Corporation
pursuant to the terms of the merger agreement with respect to that acquisition,
as amended, nor the Company's acquisition of CareInsite pursuant to the terms of
the merger agreement with respect to that acquisition, as amended, shall
constitute a Change of Control for purposes of your Employment Agreement dated
September 30, 1998, as amended by that letter agreement dated May 20, 1999 (the
"Employment Agreement") and your service as the Company's Co-CEO as provided in
the Medical Manager merger agreement shall not constitute a change in duties or
position for purposes of Section 3.2(b)(i) of your Employment Agreement.

                  This letter, the Amended Option Agreement and Exhibit B hereto
shall apply regardless of whether or not the Company acquires Medical Manager
Corporation and CareInsite, Inc. and constitute the entire agreement of the
parties and shall supersede any and all previous contracts, arrangements or
understandings between the parties relating to the subject matter hereof,
including without limitation, your Employment Agreement.

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                   If you wish to accept the terms of this letter, please
indicate by signing below and returning the signed copy to the undersigned at
the address set forth above.

                                     Sincerely,

                                     Healtheon/WebMD Corporation

                                     By:  /s/ Jack Dennison
                                        ----------------------------------------
                                         Authorized Representative
Accepted and Agreed:

     /s/ Jeff Arnold
-------------------------------

Jeffrey T. Arnold

September 12, 2000

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                                                                      EXHIBIT A

                  AMENDED AND RESTATED STOCK OPTION AGREEMENT dated as of
September 12, 2000 (the "Agreement") between HEALTHEON/WEBMD Corporation, a
Delaware corporation (the "Company"), and JEFFREY T. ARNOLD (the "Participant").

                  WHEREAS, the Company granted to the Participant nonqualified
stock options to purchase 500,000 shares of common stock, $.0001 par value, of
the Company (the "Common Shares") on May 12, 2000 under the Company's 1996 Stock
Plan, as evidenced by the Non-Qualified Stock Option Notice dated May 12, 2000
(the "May Option Agreement") from the Company to the Participant;

                  WHEREAS, the Company granted to the Participant nonqualified
stock options to purchase 1,500,000 Common Shares on August 1, 2000 under the
Company's 2000 Long-Term Incentive Plan, as evidenced by the Non-Qualified Stock
Option Notice dated August 1, 2000 (the "August Option Agreement") from the
Company to the Participant;

                  WHEREAS, the Company and Participant desire to amend and
restate the May Option Agreement and the August Option Agreement, and to that
end such agreements are hereby amended and replaced with this Agreement, upon
the terms and conditions hereinafter set forth;

                  NOW, THEREFORE, in consideration of the covenants and
agreements herein contained, the parties hereto agree as follows:

                  1.       Confirmation of Grant of Options; Effectiveness.
Pursuant to a determination by the Stock Option Committee (the "Committee") of
the Board of Directors of the Company (the "Board"), the Company hereby confirms
that the Participant has been granted (i) effective as of May 12, 2000 (a "Date
of Grant"), and subject to the terms and conditions of this Agreement,
nonqualified stock options (the "May Options") to acquire 500,000 Common Shares
and (ii) effective as of August 1, 2000 (a "Date of Grant"), and subject to the
terms and conditions of this Agreement, nonqualified stock options (the "August
Options, and together with the May Options, the "Options") to acquire 1,500,000
Common Shares. Each such Option shall entitle the Participant to purchase, upon
payment of $16.03 (the "Option Price"), one Common Share. The Options shall be
exercisable as hereinafter provided.

                  2.       Certain Restrictions. None of the Options may be
sold, transferred, assigned, pledged, or otherwise encumbered or disposed of,
except by will or the laws of descent and distribution; provided, however, that
the Committee shall permit the transfer of an Option to the Participant's family
members, to one or more trusts established in whole or in part for the benefit
of one or more of such family members or to any other entity that is owned by
such family members. During the Participant's lifetime, an Option shall be
exercisable only by the Participant or by the Participant's guardian, legal
representative or permitted transferee. Each transferee of an Option by will or
the laws of descent and distribution or other permitted transferee shall, as a
condition to the transfer thereof, execute an agreement pursuant to which it
shall become a party to this Agreement. Any attempt to sell, transfer, assign,
pledge or otherwise encumber or dispose of any Option contrary to the provisions
of this Agreement, and any levy, attachment or similar process upon any Option
shall be null and void and without effect.

                  3.       Terms and Conditions of Options. The Options
evidenced hereby are subject to the following terms and conditions:
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                  (a)      Vesting. Subject to Section 3(c), the Options shall
vest (the "Vested Options") as to one forty-eighth (1/48th) of the Options on
the first day of each month after the Date of Grant for 48 consecutive months
until fully vested (i.e., The Participant will become fully vested with respect
to the May Options on May 1, 2004 and with respect to the August Options on
August 1, 2004) (the "Vesting Date").

                  (b)      Exercisability. Subject to Section 3(c), the
Participant may exercise Vested Options, in whole or in part, to purchase a
whole number of Common Shares.

                  (c)      Option Period. (i) The Vested Options shall not be
exercisable following the tenth anniversary of the Date of Grant, and shall be
subject to earlier termination as provided in Section 3(c)(iii).

                  (ii)     In the event that the Participant's employment with
the Company and its subsidiaries is terminated (A) as a result of the
Participant's death or the Participant becoming Disabled (as defined below), (B)
by the Company without Cause (as defined below) or (C) by the Participant for
Good Reason (as defined below), the Options shall be fully vested and
exercisable as of the date on which such employment terminates.

                  (iii)    In the event that the Participant's employment with
the Company and its subsidiaries is terminated by the Company for Cause or by
the Participant without Good Reason, all unvested Options shall terminate and be
cancelled without any consideration being paid therefor; provided, however, that
a change in the Participant's status with the Company from Co-Chief Executive
Officer or Chief Executive Officer to any other position (including Chairman)
with the consent of the Company and the Participant shall not be treated as a
termination of the Participant's employment for purposes of this Agreement.

                  (iv)     In the event that the Participant's employment with
the Company and its subsidiaries terminates for any reason, the Participant (or
the Participant's estate) shall be entitled to exercise the Options which have
become Vested Options as of the date of termination until the tenth anniversary
of the Date of Grant.

                  (v)      In the event of a Change in Control (as defined
below), the Options shall be fully vested and exercisable as of the date on
which such Change in Control occurs. For purposes of this Agreement, a "Change
in Control" means a transaction (other than the transactions contemplated by the
Merger Agreement between Medical Manager Corporation and the Company) that
occurs after the Effective Time (as defined in that Merger Agreement), if:

                  1.       Any person, entity or group shall have acquired, in
         one or more transactions, the beneficial ownership of at least 50
         percent of the voting power of the outstanding voting securities of the
         surviving corporation; or

                  2.       The sale of all or substantially all of the assets
         of the surviving corporation to a person, entity or group occurs in a
         transaction (except for a sale-leaseback transaction) where the
         surviving corporation or the holders of the common stock of the
         surviving corporation do not receive (i) voting securities representing
         a majority of the voting power entitled to vote on a regular basis for
         the board of directors of the acquiring entity or of an affiliate which
         controls the acquiring entity, or (ii) securities representing a

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         majority of the equity interest in the acquiring entity or of an
         affiliate that controls the acquiring entity, if other than a
         corporation; or

                  3.       A complete liquidation or dissolution of the
         surviving corporation shall have occurred;

                  provided, however, that the provisions of this clause (v)
shall be subject to any necessary approvals by the Committee.

                  (d)      Certain Definitions. (i) For purposes of this
Agreement, "Cause" means a final, non-appealable court adjudication in a civil
or criminal proceeding that the Participant has during his employment committed
a fraud or felony directed against the Company relating to or adversely
affecting his employment.

                  (ii)     For purposes of this Agreement, the Participant shall
be "Disabled" if the Participant becomes incapacitated by bodily injury or
disease (including as a result of mental illness) so as to be unable to
regularly perform the duties of his position for a period in excess of 180 days
in any consecutive twelve-month period.

                  (iii)    For purposes of this Agreement, "Good Reason" means
any of the following:

                  1.       a reduction in the Participant's title or
         responsibilities with the Company, or if he is required to report to
         any person other than the full Board;

                  2.       any reduction in any compensation or fringe benefits
         provided by the Company;

                  3.       any breach by the Company of this Agreement or any
         other material agreement between the Company and the Participant;

                  4.       any requirement that the Participant, without his
         consent, be based at any office or location other than in Atlanta,
         Georgia.

                  (e)      Notice of Exercise. Subject to Sections 3(f) and 5(a)
hereof, the Participant may exercise any or all of the Vested Options by giving
written notice to the Chief Financial Officer of the Company at its principal
business office. The date of exercise of a Vested Option shall be the later of
(i) the date on which the Chief Financial Officer of the Company receives such
written notice or (ii) the date on which the conditions provided in Sections
3(f) and 5(a) hereof are satisfied.

                  (f)      Payment. Prior to the issuance of a certificate
pursuant to Section 3(i) hereof evidencing Common Shares, the Participant shall
have paid to the Company the Option Price of all Common Shares purchased
pursuant to exercise of such Options, in cash or by certified or official bank
check, and all applicable tax withholding obligations as provided in Section
5(a) of this Agreement. The Option Price may also be payable by a customary
"cashless" exercise procedure through a broker or in such other form as the
Committee may approve.

                  (g)      Shareholder Rights. The Participant shall have no
rights as a shareholder with respect to any Common Shares issuable upon the
exercise of an Option until a certificate or

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certificates evidencing such shares shall have been issued to the Participant,
and, except as provided in Section 6, no adjustment shall be made for dividends
or distributions or other rights in respect of any share for which the record
date is prior to the date upon which the Participant shall become the holder of
record thereof.

                  (h)      Compliance with Securities Laws. The Company shall,
on or prior to the date on which an Option becomes exercisable, use its best
efforts to (A) file a registration statement with the Securities and Exchange
Commission on Form S-8 with respect to the Common Shares subject to such Option
and cause such registration statement to be declared effective and remain
effective for so long as any Option remains outstanding and (B) qualify such
Common Shares under applicable state "blue sky" laws (or determine that an
exemption under such blue sky laws is available) and cause such Common Shares to
remain so qualified (or exempt) for so long as any Option remains outstanding.

                  (i)      Issuance of Certificate. As soon as practicable
following the exercise of any Options, a certificate evidencing the number of
Common Shares issued in connection with such exercise shall be issued in the
name of the Participant.

                  4.       Representations and Warranties. The Company and the
Participant represent that this Agreement has been duly executed and delivered
by such party and constitutes a legal, valid and binding agreement of such
party, enforceable against such party in accordance with its terms, except as
limited by any applicable bankruptcy, insolvency, reorganization, moratorium or
similar law affecting creditors' rights generally and by general principles of
equity.

                  5.       Miscellaneous.

                  (a)      Tax Withholding. The Company and its subsidiaries
shall have the right to require the Participant to remit to the Company, prior
to the delivery of any certificates evidencing Common Shares pursuant to the
exercise of an Option, any amount sufficient to satisfy any minimum federal,
state or local tax withholding requirements. Prior to the Company's
determination of such withholding liability, the Participant shall have the
right to make an irrevocable election to satisfy, in whole or in part, such
obligation to remit taxes by directing the Company to withhold Common Shares
that would otherwise be received by the Participant.

                  (b)      No Restriction on Right of Company to Effect
Corporate Changes. Subject to Section 6, this Agreement shall not affect in any
way the right or power of the Company or its stockholders to make or authorize
any or all adjustments, recapitalizations, reorganizations or other changes in
the capital structure or business of the Company, or any merger or consolidation
of the Company, or any issue of stock or of options, warrants or rights to
purchase stock or of bonds, debentures, preferred or prior preference stocks
whose rights are superior to or affect the Common Shares or the rights thereof
or which are convertible into or exchangeable for Common Shares, or the
dissolution or liquidation of the Company, or any sale or transfer of all or any
part of the assets or business of the Company, or any other corporate act or
proceeding, whether of a similar character or otherwise.

                  6.       Adjustment.

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                  The number and price per Common Share covered by any Option,
and any other rights under any Option, shall be appropriately adjusted by the
Board or the Committee, as the case may be, to reflect any subdivision (stock
split) or consolidation (reverse split) of the issued Common Shares, or any
other recapitalization of the Company, or any business combination or other
transaction involving the Company (including, without limitation, rights
offerings and issuances of securities for consideration that is less than the
fair market value thereof), which shall affect the rights of holders of Common
Shares. The Committee or the Board, as the case may be, shall provide for
appropriate adjustment of the Options in the event of stock dividends or
distributions of assets or securities owned by the Company to its stockholders.
Without limiting the foregoing, any adjustment pursuant to this Section 6 shall
(i) be on terms that are no less favorable to the Participant than those
applicable to any other holder of stock options or convertible securities issued
by the Company and (ii) entitle the Participant to receive, upon exercise of the
Options, in addition to the Common Shares that remain subject to such Options,
such stock, securities, other property and rights that the Participant, as a
holder of Common Shares, would have received if such Options had been exercised
prior to the date of the applicable event or transaction described in this
Section 6.

                  7.       Survival; Assignment.

                  All agreements, representations and warranties made herein and
in any certificates delivered pursuant hereto shall survive the issuance to the
Participant of the Options and the Common Shares and, notwithstanding any
investigation heretofore or hereafter made by the Participant or the Company or
on the Participant's or the Company's behalf, shall continue in full force and
effect. Without the prior written consent of the Company, the Participant may
not assign any of his rights hereunder except as permitted by Section 2.
Whenever in this Agreement any of the parties hereto is referred to, such
reference shall be deemed to include the heirs and permitted successors and
assigns of such party; and all agreements herein by or on behalf of the Company,
or by or on behalf of the Participant, shall bind and inure to the benefit of
the heirs and permitted successors and assigns of such parties hereto.

                  8.       Gross-Up Payment(i) Anything in this Agreement to the
contrary or any termination of the Options notwithstanding, in the event it
shall be determined that any payment or distribution or benefit received or to
be received by the Participant pursuant to the terms of this Agreement or any
other payment or distribution or benefit made or provided by the Company, or any
of its subsidiaries and affiliates, to or for the benefit of the Participant
(whether pursuant to this Agreement or otherwise and determined without regard
to any additional payments required under this Section 8) (a "Payment") would be
subject to the excise tax imposed by Section 4999 of the Internal Revenue Code
of 1986, as amended (the "Code") or any interest or penalties are incurred by
the Participant with respect to such excise tax (such excise tax, together with
any such interest and penalties, is hereinafter collectively referred to as the
"Excise Tax"), then the Participant shall be entitled to receive an additional
payment (a "Gross-Up Payment") in an amount such that after payment by the
Participant of all taxes (including any interest or penalties imposed with
respect to such taxes), including, without limitation, any income and employment
taxes (and any interest and penalties imposed with respect thereto) and Excise
Tax imposed upon the Gross-Up Payment, the Participant retains an amount of the
Gross-Up Payment equal to the sum of (x) the Excise Tax imposed upon the
Payments and (y) the product of any deductions actually disallowed under Section
68 of the Code solely as a direct result of the inclusion of the Gross-Up
Payment in the Participant's adjusted gross income and the highest applicable
marginal rate of federal income taxation for the

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calendar year in which the Gross-Up Payment is to be made. For purposes of
determining the amount of the Gross-Up Payment, the Participant shall be deemed
to (i) pay federal income taxes at the highest marginal rates of federal income
taxation for the calendar year in which the Gross-Up Payment is to be made and
(ii) pay applicable state and local income taxes at the highest marginal rate of
taxation for the calendar year in which the Gross-Up Payment is to be made, net
of the maximum reduction in federal income taxes which could be obtained from
deduction of such state and local taxes.

                  (ii)     Subject to the provisions of Sections 8(i) and
8(iii), all determinations required to be made under this Section 8, including
whether and when a Gross-Up Payment is required and the amount of such Gross-Up
Payment and the assumptions to be utilized in arriving at such determination,
shall be made by the Company's certified public accounting firm (the "Accounting
Firm"), which shall provide detailed supporting calculations both to the Company
and the Participant within 15 business days of the receipt of notice from the
Participant or the Company that there has been a Payment, or such earlier time
as is requested by the Company. All fees and expenses of the Accounting Firm
shall be borne solely by the Company. Any Gross-Up Payment, as determined
pursuant to this Section 8, shall be paid by the Company to the Participant
within five days of the receipt of the Accounting Firm's determination. Any
determination by the Accounting Firm shall be binding upon the Company and the
Participant. As a result of the uncertainty in the application of Section 4999
of the Code at the time of the initial determination by the Accounting Firm
hereunder, it is possible that Gross-Up Payments which will not have been made
by the Company should have been made ("Underpayment"), consistent with the
calculations required to be made hereunder. In the event that the Company
exhausts its remedies pursuant to Section 8(iii) and the Participant thereafter
is required to make a payment of any Excise Tax, the Accounting Firm shall
determine the amount of the Underpayment that has occurred and any such
Underpayment shall be promptly paid by the Company to or for the benefit of the
Participant.

                  (iii)    The Participant shall notify the Company in writing
of any claim by the U.S. Internal Revenue Service (the "IRS") that, if
successful, would require the payment by the Company of the Gross-Up Payment.
Such notification shall be given as soon as practicable but no later than ten
business days after the Participant is informed in writing of such claim and
shall apprise the Company of the nature of such claim and the date on which such
claim is requested to be paid. The Participant shall not pay such claim prior to
the expiration of the 30-day period following the date on which the Participant
gives such notice to the Company (or such shorter period ending on the date that
any payment of taxes with respect to such claim is due). If the Company notifies
the Participant in writing prior to the expiration of such period that it
desires to contest such claim, the Participant shall:

                  (a)      give the Company any information reasonably requested
by the Company relating to such claim;

                  (b)      take such action in connection with contesting such
claim as the Company shall reasonably request in writing from time to time,
including, without limitation, accepting legal representation with respect to
such claim by an attorney reasonably selected by the Company; and

                  (c)      cooperate with the Company in good faith in order
effectively to contest such claim;

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provided, however, that the Company shall bear and pay directly all costs and
expenses (including additional interest and penalties) incurred in connection
with such contest and shall indemnify and hold the Participant harmless, on an
after-tax basis, for any Excise Tax or income and employment tax (including
interest and penalties with respect thereto) imposed as a result of such
representation and payment of costs and expenses. Without limitation on the
foregoing provisions of this Section 8(iii), the Company shall control all
proceedings taken in connection with such contest and, at its sole option, may
pursue or forgo any and all administrative appeals, proceedings, hearings and
conferences with the taxing authority in respect of such claim and may, at its
sole option, either direct the Participant to pay the tax claimed and sue for a
refund or contest the claim in any permissible manner, and the Participant shall
agree to prosecute such contest to a determination before any administrative
tribunal, in a court of initial jurisdiction and in one or more appellate
courts, as the Company shall determine; provided, however, that if the Company
directs the Participant to pay such claim and sue for a refund, the Company
shall advance the amount of such payment to the Participant, on an interest-free
basis and shall indemnify and hold the Participant harmless, on an after-tax
basis, from any Excise Tax or income and employment tax (including interest or
penalties with respect thereto) imposed with respect to such advance or with
respect to any imputed income with respect to such advance; and provided
further, that any extension of the statute of limitations relating to payment of
taxes for the taxable year of the Participant with respect to which such
contested amount is claimed to be due is limited solely to such contested
amount. Furthermore, the Company's control of the contest shall be limited to
issues with respect to which a Gross-Up Payment would be payable hereunder and
the Participant shall be entitled to settle or contest, as the case may be, any
other issue (an "Other Issue") raised by the IRS or any other taxing authority;
provided, however, that if, solely as a result of any contest by the Company
pursuant to this Section 8(iii), the Participant's ability to settle or
otherwise resolve any such Other Issue is delayed, then the Company will
reimburse the Participant, on an after-tax basis, for any additional interest
incurred by the Participant as a result of such delay.

                  (iv)     If, after the receipt by the Participant of an amount
advanced by the Company pursuant to Section 8(iii), the Participant becomes
entitled to receive any refund with respect to such claim, the Participant shall
(subject to the Company's complying with the requirements of Section 8(iii)
promptly pay to the Company the amount of such refund (together with any
interest paid or credited thereon after taxes applicable thereto). If, after the
receipt by the Participant of an amount advanced by the Company pursuant to
Section 8(iii), a determination is made that the Participant shall not be
entitled to any refund with respect to such claim and the Company does not
notify the Participant in writing of its intent to contest such denial of refund
prior to the expiration of 30 days after such determination, then such advance
shall be forgiven and shall not be required to be repaid and the amount of such
advance shall offset, to the extent thereof, the amount of Gross-Up Payment
required to be paid.

                  9.       Severance; Consulting Engagement. In the event that
the Participant terminates his employment with the Company and its subsidiaries
with Good Reason or the Company terminates the employment of the Participant
without Cause, the Company shall pay to the Participant, in lieu of any other
cash severance provided for in any other agreement, an amount equal to 12 months
of his then-current base salary, if any, less applicable withholding taxes
pursuant to the Company's customary payroll practices, which amount shall be due
in full within 5 days of such termination. In the event that the Participant
terminates his employment with the Company and its subsidiaries without Good
Reason after March 12, 2000 but prior to September 12, 2003, the Participant
shall, at the request of the Company, make himself available

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to provide consulting and advisory services (the "Consulting Services") to the
Company during the period beginning on the date of termination and ending on
September 12, 2003; provided, however, that such Consulting Services shall be
performed at such times and places as are acceptable to the Participant in his
sole discretion. The Participant shall not be entitled to receive any additional
compensation for the Consulting Services.

                  10.      Notices. All notices and other communications
provided for herein shall be in writing and shall be delivered by hand or sent
by certified or registered mail, return receipt requested, postage prepaid,
addressed, if to the Participant, to his attention at the most recent mailing
address that the Company has on record and, if to the Company, to it at 3399
Peachtree Street NE, 400 The Lennox Building, Atlanta, Georgia 30326, Attention:
General Counsel. All such notices shall be conclusively deemed to be received
and shall be effective, if sent by hand delivery, upon receipt, or if sent by
registered or certified mail, on the fifth day after the day on which such
notice is mailed.

                  11.      Waiver. The waiver by either party of compliance with
any provision of this Agreement by the other party shall not operate or be
construed as a waiver of any other provision of this Agreement, or of any
subsequent breach by such party of a provision of this Agreement.

                  12.      Source of Rights. This Agreement shall be the sole
and exclusive source of any and all rights which the Participant, and the
Participant's personal representatives or heirs at law, may have in respect of
the Options as granted hereunder.

                  13.      Captions. The captions contained in this Agreement
are for reference purposes only and shall not affect the meaning or
interpretation of this Agreement.

                  14.      Entire Agreement; Governing Law; Jurisdiction. This
Agreement sets forth the entire agreement and understanding between the parties
hereto and supersedes all prior agreements and understandings relating to the
subject matter hereof. This Agreement may be executed in one or more
counterparts, each of which shall be deemed to be an original, but all such
counterparts shall together constitute one and the same agreement. The headings
of sections and subsections herein are included solely for convenience of
reference and shall not affect the meaning of any of the provisions of this
Agreement. This Agreement shall be governed by, and construed in accordance
with, the laws of the State of Delaware (without reference to the choice of law
provisions of Delaware law) applicable to contracts executed and to be wholly
performed within such State, and the State or Federal court sitting in Fulton
County, Georgia shall have exclusive jurisdiction of the Company and the
Participant for purposes of adjudicating any disputes under this Agreement. The
Participant and the Company hereby consent to personal jurisdiction and venue in
the State or Federal court sitting in Fulton County, Georgia and hereby waive
any claim or defense that the party lacks minimum contacts with the forum, that
such State or Federal court lacks personal jurisdiction of the parties, or that
such State or Federal court is an improper or inconvenient venue.

                                       8
<PAGE>   13

                  IN WITNESS WHEREOF, the Company has caused this Agreement to
be executed by its duly authorized officer and the Participant has executed this
Agreement, both as of the day and year first above written.

                                      HEALTHEON/WEBMD CORPORATION

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

                                      PARTICIPANT

                                      -----------------------------------------
                                      Jeffrey T. Arnold

                                       9

<PAGE>   14

                                                                       EXHIBIT B

                   NONCOMPETITION; NONSOLICITATION PROVISIONS

1.       Background. Jeffrey T. Arnold ("Arnold") acknowledges and agrees that:

                  (a)      Healtheon/WebMD Corporation and each of its direct
and indirect subsidiaries (collectively, the "Companies") are currently engaged
in the following businesses: (i) development or provision of an Internet-based
healthcare electronic commerce network that links physicians, payers, suppliers
or patients, (ii) facilitating or processing administrative or clinical
healthcare transactions, (iii) clinical and administrative healthcare related
electronic commerce business, and (iv) development or provision of physician
practice management information systems or other healthcare software systems
relating to administrative and clinical functions, to physicians, practice
associations, management service organizations, physician practice management
organizations or other providers of healthcare services (collectively, the
"Business"). The Business is conducted by the Companies throughout the United
States.

                  (c)      In order to protect the Business (defined above) of
the Company, and as a condition to the Company's execution of the Amended Option
Agreement, the Company is requiring Arnold to agree to become bound to the
provision of this Exhibit B.

                  (f)      The provisions of this Exhibit B are reasonable in
light of the substantial benefit that will accrue to Arnold through the Amended
Option Agreement and are reasonably necessary to protect the Business of the
Company.

2.       Noncompete. Arnold agrees that for the period ending on the earlier of
(i) the second (2nd) anniversary of the later of the date (the "Termination
Date") of Arnold's resignation or removal as Co-Chief Executive Officer, Chief
Executive Officer or as a director of the Company or any successor to its
Business or (ii) September 12, 2003 (the "Restrictive Period"), without the
prior written consent of the Company, Arnold shall not Compete (defined below)
with the Business of the Companies, except as otherwise permitted under this
Section 2. For purposes of this Agreement, "Compete" shall mean: (i) within the
Territory (defined below), to engage in a business or business activities that
are either (A) substantially similar to, or (B) competitive with, the Business,
in each case as engaged in by the Companies on the date hereof including changes
in and expansions of such Business reasonably anticipated on the date hereof
(collectively, a "Competitive Business"); (ii) to assist any person or entity
(whether in a managerial, financial, employment, advisory or other capacity or
as a stockholder or owner, except as set forth in clause (iii) below) to engage
in a Competitive Business; or (iii) to own any interest in or to organize a
corporation, partnership or other business or organization which engages in a
Competitive Business; provided, however, that nothing in clause (iii) above
shall prohibit Arnold from acquiring or holding, for investment purposes only,
less than five percent (5%) of the outstanding publicly traded securities of any
corporation which may compete directly or indirectly with the Business; or less
than five percent (5%) of the outstanding securities of any corporation,
partnership or other business or organization, whether or not publicly traded,
which competes directly or indirectly with the Business so long as he is not
employed by and does not consult with, or become a director of or otherwise
engage in activities for such competing

<PAGE>   15

company; provided further that this provision shall not apply in the event the
Company or the Company's direct or indirect subsidiaries or any person deriving
title to the goodwill of the Business of the Companies being acquired or shares
of the Companies being acquired ceases to carry on a business comparable to the
Business of the Companies within the Territory; provided further that this
provision shall not prevent or impair Arnold from performing usual investment
banking services for a person or entity engaged in a Competitive Business if
such services do not materially relate to or involve such Competitive Business.

                  "Territory" shall mean (a) the area within a 100 mile radius
of that office of the Company from which Arnold performed the majority of his
services during the one-year period ending on the earlier of his resignation or
removal as a director of the Company, or the 3rd anniversary of the date hereof
(the "Applicable Date"), (b) the state in which Arnold is resident on the
Applicable Date, and (c) any other state in the United States in which the
Companies develop, distribute or provide their business services or products as
of the Applicable Date.

3.       Confidentiality. Arnold acknowledges that in the course of serving as
Chief Executive Officer of the Company and as a result of his relationship with
the Companies he has had and will continue to have access to and will learn
information that is proprietary to, or confidential to the Companies and that
concerns the Business including the operation, methodology and plans of the
Companies and their Affiliates (as defined below), including without limitation,
business strategy and plans, financial information, trade secrets, market
information developments (as defined below), information regarding acquisition
and other strategic partner candidates and customer information (collectively,
"Proprietary Information"). Arnold agrees that during the period beginning on
the date hereof and ending upon the later of (i) the end of the Restrictive
Period or (ii) the first anniversary of the Termination Date, he will keep such
Proprietary Information confidential and will not disclose directly or
indirectly any such Proprietary Information to any third party and will not
misuse, misappropriate or exploit such Proprietary Information in any way except
as required by law or regulatory body. Upon his resignation or removal as
Co-Chief Executive Officer or Chief Executive Officer of the Company, Arnold
shall immediately return to the Company all copies of Proprietary Information in
his possession (except his Rolodex).

4.       Nonsolicitation. During the period beginning on the date hereof and
ending upon the end of the Restrictive Period, Arnold shall not directly or
indirectly without the express written approval of the Board of Directors of the
Company, solicit any customer, or any person or entity who is reasonably
expected to become a customer of the Companies or any entity the equity of which
is owned at least 40% by the Company or any of the Companies (an "Affiliate")
for any commercial pursuit which is a Competitive Business. During the period
beginning on the date hereof and ending upon the end of the Restrictive Period,
Arnold shall not directly or indirectly solicit or induce, or attempt to induce,
any employees, agents, or consultants of the Company, the Companies or their
Affiliates to leave the employ of the Company, the Companies or their Affiliates
or to do anything from which Arnold is restricted by reason of this letter
agreement, nor shall Arnold, directly or indirectly, offer or aid others to
offer employment to or interfere or attempt to interfere with any employees,
agents or consultants of the Companies or their Affiliates.

                                       2

<PAGE>   16

5.       Construction. Arnold hereby expressly acknowledges and agrees as
follows:

                  (A) the covenants set forth in Sections 2 through 4 above are
reasonable in all respects and are necessary to protect the legitimate business
and competitive interests of the Company; and

                  (B) The provisions of this Exhibit B shall be governed by the
laws of the state of Delaware (other than the choice of law provisions of
Delaware law). In the event that any provision of this Exhibit B shall be held
invalid or unenforceable by a court of competent jurisdiction by reason of the
geographic or business scope or the duration thereof of such covenant, or for
any other reason, such invalidity or unenforceability shall attach only to the
particular aspect of such provision found invalid or unenforceable as applied
and shall not affect or render invalid or unenforceable any other provision of
this Exhibit B and the provision shall be construed as if the geographic or
business scope or the duration of such provision or other basis on which such
provisions have been challenged had been more narrowly drafted so as not to be
invalid or unenforceable.

6.       Enforcement; Remedies. Arnold covenants, agrees and recognizes that
because the breach of the covenants, or any of them, contained in Sections 2
through 4 hereof may result in immediate and irreparable injury to the Company,
the Company shall be entitled to seek an injunction restraining Arnold from any
violation of Sections 2 through 4 to the fullest extent allowed by law. Arnold
further covenants and agrees that in the event of a material breach of any of
the respective covenants and agreements contained in Sections 2 through 4
hereof, the period during which Arnold is obligated to refrain from competing
shall be extended for the entire period of such breach. Arnold further
covenants, agrees and recognizes that, notwithstanding anything to the contrary
contained herein, in the event of a material breach of any of the respective
covenants and agreements contained in Sections 2 through 4 hereof, which remains
uncured 30 days after written notice from the Company, further vesting with
respect to the Current Options shall cease. The Company's entitlement to seek
injunctive relief or ceasing any further Current Option vesting, as described in
this Section 6, shall be the Company's sole and exclusive remedy in the event
that Arnold breaches any covenant or agreement contained in this Exhibit A;
provided, however, that in the case of any willful material breach by Arnold of
the covenants and agreements contained in Sections 2 through 4 hereof, nothing
herein shall be construed as prohibiting the Company from pursuing any other
legal or equitable remedies that may be available to it for any such breach,
including the recovery of damages from Arnold.

                                       3<PAGE>   1
                                                                   EXHIBIT 10.23

Letter Agreement dated October 11, 2000 between Registrant and Jeffrey T. Arnold

<PAGE>   2

                                WEBMD CORPORATION
                            3399 PEACHTREE STREET NE
                             400 THE LENOX BUILDING
                             ATLANTA, GEORGIA 30326

                                October 11, 2000

Mr. Jeffrey T. Arnold
500 Peachtree Battle Ave.
Atlanta, Georgia  30305

Dear Mr. Arnold:

                  This letter agreement (the "Agreement") sets forth our mutual
agreement concerning your resignation as a director, executive officer and
employee of WebMD Corporation, a Delaware corporation (the "Company").

                  1.       Resignation. Your employment with the Company and its
subsidiaries and affiliates will terminate in all capacities on October 11, 2000
(the "Effective Time"). This Agreement has been duly authorized by the Company's
Board of Directors (the "Board"). In that regard, you hereby resign, effective
as of the Effective Time, from your positions as Co-Chief Executive Officer and
a director of the Company and from all other officerships, directorships and
positions that you currently hold with the Company or any of its subsidiaries or
affiliates.

                  2.       Severance Benefits. The Company will provide you with
the following severance payments and benefits:

                  (a)      Severance. The Company will pay you an amount equal
to $4,000,000, payable on or before October 12, 2000 by wire transfer to an
account to be designated by you.

                  (b)      Continuation of Insurance Coverage. The Company will
continue (or provide comparable substitute coverage) your health, dental,
disability and life insurance coverage, and continue to pay the employer portion
of the applicable premiums, until the earlier of the 18-month anniversary of the
Effective Time and the date on which you are covered under another comparable
plan. You agree to promptly notify the Company in writing in the event that you
obtain coverage under another such plan.

                  (c)      401(k) Plan. You will be entitled to receive your
vested accrued benefits under the Company's 401(k) plan in accordance with the
terms and conditions of such plan.

                  (d)      No Other Compensation or Benefits. Except as
otherwise specifically provided herein, you will not be entitled to any
compensation or benefits or to participate in any past, present or future
employee benefit programs or arrangements of the Company or any of its
subsidiaries or affiliates after the Effective Time.

                  3.       Company Stock Options. Your options (the "Options")
(i) to purchase 2,000,000 shares of the Company's common stock ("Common Stock"),
as evidenced by the

<PAGE>   3

Amended and Restated Stock Option Agreement dated as of September 12, 2000 (the
"Amended Option Agreement") between the Company and you, and (ii) to purchase an
additional 2,486,741 shares of Common Stock will remain subject to, and will be
exercisable in accordance with, the terms and conditions thereof (including,
without limitation, the Letter Agreement dated September 12, 2000 between the
Company and you (the "Letter Agreement") but without regard to the Employment
Agreement dated as of September 30, 1998 (the "Employment Agreement") between
the Company and you). It is hereby expressly agreed that the termination of your
employment will be treated as a termination without "cause" for purposes of the
Options (including, without limitation, for purposes of Sections 1 and 3 of the
Letter Agreement and Section 3(c)(ii) of the Amended Option Agreement), and all
of your Options shall, upon the Effective Time of this Agreement, become fully
vested and remain exercisable for ten years from their respective dates of
grant.

                  4.       Restrictive Covenants. (i) The provisions of Exhibit
B to the Letter Agreement are incorporated herein by reference as if such
provisions were set forth herein in full.

                  (ii)     The first paragraph of Section 2 of Exhibit B to the
Letter Agreement is hereby amended to add the following to the end thereof:

         "provided, further, that this provision shall not prevent or impair
         Arnold from engaging in raising donations for public charitable
         purposes for existing not-for-profit nationally recognized charitable
         organizations engaged in a Competitive Business so long as (i) he is
         not employed by, and does not become an officer, director or trustee or
         serve in a similar capacity of or receive compensation or other profit
         from such not-for-profit charitable organization and (ii) such
         activities do not relate to or involve such Competitive Business other
         than to the extent such raising of donations presents consumer-oriented
         health and wellness information in furtherance with the not-for-profit
         charitable organization's mission."

                  5.       Cooperation. From and after the date hereof through
the third anniversary of the Effective Time you will (i) cooperate in all
reasonable respects (after taking into account any employment obligations you
may have) with the Company and its affiliates and their respective directors,
officers, attorneys and experts in connection with the conduct of any action,
proceeding, investigation or litigation brought by a third party other than the
Company, involving the Company or any of its affiliates, including any such
action, proceeding, investigation or litigation in which you are called to
testify relating to matters involving facts or events relating to the Company
that arose during your employment with the Company and (ii) promptly respond to
all reasonable requests by the Company and its affiliates relating to
information concerning actual customers of the Company during your employment
which may be in your possession, and that you received during your employment
with the Company. The Company will, as a condition to your obligations under
this Section 5, reimburse you for any reasonable out of pocket expenses incurred
as a result of such cooperation, provided that such expenses have been approved
in writing in advance by the Chief Executive Officer or Chief Financial Officer
of the Company.

                                       2

<PAGE>   4

                  6.       Return of Property. Within 10 days after the
Effective Time, you will surrender to the Company all property of the Company
and its affiliates in your possession and all property made available to you in
connection with your employment by the Company, including, without limitation,
any and all records, manuals, customer lists, notebooks, computers, computer
programs and files, papers, electronically stored information and documents kept
or made by you in connection with your employment; provided, however, that you
will be permitted to retain the property listed on Annex A hereto. You will be
given reasonable access to Company premises through October 18, 2000 to retrieve
your personal property. Notwithstanding the foregoing, the Company shall have
the right to retrieve any electronically stored information which is found or
stored in any of the computer equipment listed on Annex A which is otherwise
property owned by the Company or any of its subsidiaries or affiliates and take
any action necessary to delete all such information from the computer
equipment's hard-drive or other memory device.

                  7.       Communications. You and the Company agree that the
press release and related statement regarding your termination of employment
will be in the form attached hereto as Annex B, and that no subsequent comments
should be made to the media or through other public statements by either party
or by any subsidiary, officer or director of the Company regarding your
termination of employment that are inconsistent with such statement. From and
after the Effective Time, you will refrain from taking actions or making public
statements, written or oral, which denigrate, disparage or defame the goodwill
or reputation of the Company and its subsidiaries and their former and current
executive officers and directors. From and after the Effective Time, the Company
will refrain, and will cause its executive officers and directors to refrain,
from taking actions or making public statements, written or oral, which
denigrate, disparage or defame your reputation. The restrictions set forth in
this Section 7 will be subject to such exceptions as are required by law or in
connection with a judicial proceeding.

                  8.       Release. (a) General Release. In consideration of the
Company's obligations under this Agreement and for other valuable consideration,
you hereby release and forever discharge the Company, its subsidiaries and
affiliates and each of their respective officers, employees, directors and
agents (the "Company Releasees") from any and all claims, actions and causes of
action (collectively, "Claims"), including, without limitation, any Claims
arising under any applicable federal, state, local or foreign law, that you may
have, or in the future may possess, arising out of (x) your employment
relationship with and service as a director, employee or officer of the Company
or any of its subsidiaries or affiliates, and the termination of such
relationship or service, or (y) any event, condition, circumstance or obligation
that occurred, existed or arose on or prior to the date hereof; provided,
however, that the release set forth in this Section 8(a) will not apply to (A)
the obligations of the Company under this Agreement, (B) the obligations of the
Company and its subsidiaries to continue to provide director and officer
indemnification pursuant to the agreement dated as of April 22, 1998 (the
"Indemnification Agreement") between Endeavor Technologies Inc., a predecessor
to the Company, and you, which Indemnification Agreement is hereby assumed by
the Company, and Section 10 of this Agreement and (C) your right or ability to
assert in good faith any facts by way of defense (or counterclaim arising from
the same set of facts) against any Claim asserted against you by the Company
pursuant to clause (B) of the proviso to Section 8(b). You further agree that
the payments and benefits described in this Agreement will be in full
satisfaction of any and all claims for payments or benefits, whether express or
implied, that you may have

                                       3

<PAGE>   5

against the Company or any of its subsidiaries or affiliates arising out of your
employment relationship, your service as a director, employee or officer of the
Company or any of its subsidiaries or affiliates and the termination thereof.
You hereby acknowledge and confirm that you are providing the release and
discharge set forth in this Section 8(a) only in exchange for consideration in
addition to anything of value to which you are already entitled. You acknowledge
and agree that if you should hereafter make any claim or demand or commence or
threaten to commence any action, claim or proceeding against the Company
Releasees with respect to any cause, matter or thing which is the subject of
this Section 8(a), this Agreement may be raised as a complete bar to any such
action, claim or proceeding, and the applicable Company Releasee may recover
from you all costs incurred in connection with such action, claim or proceeding,
including attorneys' fees.

                  (b)      Company Release. The Company and its subsidiaries and
affiliates (the "Company Releasors") hereby release and forever discharge you,
your estate and your legal representatives (the "Individual Releasees") from any
and all Claims, including, without limitation, any Claims arising under any
applicable federal, state, local or foreign law, that it may have, or in the
future may possess, arising out of (x) your employment relationship with and
service as a director, employee or officer of the Company or any of its
subsidiaries or affiliates or predecessors, and the termination of such
relationship or service, or (y) any event, condition, circumstance or obligation
that occurred, existed or arose on or prior to the date hereof; provided,
however, that the release set forth in this Section 8(b) will not apply to (A)
your obligations under this Agreement and the plans and agreements referred to
herein and (B) any Claim which the Company has against you arising out of
fraudulent conduct by you. The Company acknowledges and agrees that if it or any
other Company Releasor should hereafter make any claim or demand or commence or
threaten to commence any action, claim or proceeding against you or the
Individual Releasees with respect to any cause, matter or thing which is the
subject of this Section 8(b), this Agreement may be raised as a complete bar to
any such action, claim or proceeding, and you or the applicable Individual
Releasee may recover from the Company Releasors all costs incurred in connection
with such action, claim or proceeding, including attorneys' fees.

                  9.       Consulting Engagement. (i) In consideration of the
payments and benefits provided to you hereunder, you agree to serve as a
consultant to the Company for the period (the "Consulting Period") beginning at
the Effective Time and ending on the fourth anniversary thereof. Your services
hereunder during the Consulting Period will consist of such consulting and
advisory services, and will be provided at such times, as may be reasonably
requested (after taking into account any obligations you may have to another
employer) from time to time by W. Michael Long; provided, however, that such
services will not be required for more than 4 days during any one-month period;
provided further, however, that you will not be required to perform such
services at the request of any person other than W. Michael Long, and that such
services may be performed at the location of your choice. The Company will
reimburse you for any reasonable out-of-pocket expenses incurred by you in
connection with the performance of such consulting and advisory services,
provided that such expenses shall not be required to be incurred by you, and
shall not be reimbursed, unless such expenses have been approved in writing in
advance by the Chief Executive Officer or Chief Financial Officer of the
Company.

                                       4

<PAGE>   6

                  (ii)     You will have no authority to bind, or make any
commitments or otherwise act on behalf of, or conduct or participate in any
discussions on behalf of, the Company or any of its subsidiaries or affiliates
in any manner whatsoever after the Effective Time without the prior written
authorization of the Board. You agree not to take any action which would cause
any third party to assume that you have such authority.

                  10.      Indemnification. The Company shall continue to
provide, and shall cause its subsidiaries to continue to provide you with
indemnification, expense advancement, exculpation of liabilities and directors
and officers liability insurance, with respect to actions or inactions by you as
an officer or director of the Company (or any of its subsidiaries) prior to the
Effective Time to the fullest extent permitted by law.

                  11.      No Set-Off or Mitigation. The Company's obligation to
make the payments provided for in this Agreement and otherwise to perform its
obligations hereunder shall not be affected by any set-off, counterclaim,
recoupment, defense or other claim, right or action which the Company may have
against you or others. Except as specifically provided in this Agreement, in no
event shall you be obligated to seek other employment or take any other action
by way of mitigation of the amounts payable to you under any of the provisions
of this Agreement, and such amounts shall not be reduced whether or not you
obtain other employment.

                  12.      Miscellaneous.

                  (a)      Entire Agreement. This Agreement, the Amended Option
Agreement (including, without limitation, Section 8 thereof), the Letter
Agreement and the related Option plans and award documents and the
Indemnification Agreement (collectively, the "Applicable Agreements") set forth
the entire agreement and understanding of the parties hereto with respect to the
matters covered hereby and supersede and replace any express or implied prior
agreement with respect to the terms of your employment and the termination
thereof which you may have had with the Company or any of its subsidiaries or
affiliates (including, without limitation, (i) the Employment Agreement and (ii)
the first sentence of Section 9 of the Amended Option Agreement). This Agreement
may be amended only by a written document signed by the parties hereto.

                  (b)      Governing Law. This Agreement and, notwithstanding
any provision to the contrary contained therein, the other Applicable
Agreements, will be governed by, and construed in accordance with, the laws of
the State of Delaware (without reference to the choice of law provisions of
Delaware law) applicable to contracts executed and to be wholly performed within
such State, and the State or Federal court sitting in New Castle County,
Delaware will have exclusive jurisdiction of the Company and you for purposes of
adjudicating any disputes under any Applicable Agreement. The Company and you
hereby consent to personal jurisdiction and venue in the State or Federal court
sitting in New Castle County, Delaware and hereby waive any claim or defense
that the party lacks minimum contacts with the forum, that such State or Federal
court lacks personal jurisdiction of the parties, or that such State or Federal
court is an improper or inconvenient venue.

                  (c)      Withholding Taxes. Any payments made or benefits
provided to you under this Agreement will be reduced by any applicable
withholding taxes.

                                       5

<PAGE>   7

                  (d)      Notices. Any notices required or made pursuant to
this Agreement will be in writing and will be deemed to have been given when
delivered or mailed by United States certified mail, return receipt requested,
postage prepaid, as follows:

                  if to Jeffrey T. Arnold
                  500 Peachtree Battle Ave.
                  Atlanta, Georgia  30305

                  with a copy to:

                  Michael S. Katzke, Esq.
                  Wachtell, Lipton, Rosen & Katz
                  51 West 52nd Street
                  New York, New York  10019-6150

                  if to the Company:

                  Jack Dennison, Esq.
                  WebMD Corporation
                  3399 Peachtree Street NE
                  400 The Lenox Building
                  Atlanta, Georgia  30326

                  with a copy to:

                  Jeffrey P. Crandall, Esq.
                  Shearman & Sterling
                  599 Lexington Avenue
                  New York, NY  10022

or to such other address as either party may furnish to the other in writing in
accordance with this Section 12(d). Notices of change of address will be
effective only upon receipt.

                  (e)      Expenses. The Company will reimburse you for any
unreimbursed reasonable business expenses incurred by you prior to the Effective
Time (including airfare from New York City to Atlanta, Georgia on October 12,
2000), pursuant to the Company's reimbursement policies, following your
presentation of an expense report to the Company. In addition, the Company shall
reimburse you for reasonable fees and expenses of your legal and tax accounting
advisors incurred in connection with the negotiation and execution of this
Agreement not to exceed $75,000 in the aggregate.

                  (f)      Enforceability/Severability. The parties hereto
affirmatively acknowledge that this Agreement, and each of its provisions, is
enforceable, and expressly agree not to challenge nor raise any defense against
the enforceability of this Agreement or any of its provisions in the future. The
invalidity or unenforceability of any provision of this Agreement shall not
affect the validity or enforceability of any other provision of this Agreement.
In the event that any provision or portion of this Agreement shall be determined
to be invalid or

                                       6

<PAGE>   8

unenforceable for any reason, the remaining provisions or portions of this
Agreement shall be unaffected thereby and shall remain in full force and effect
to the fullest extent permitted by law.

                  (g)      Successors. This Agreement shall be binding on you
and the Company and your's and the Company's respective heirs, successors and
assigns, including without limitation any corporation or other entity into which
the Company may be merged, reorganized or liquidated. Your obligations under
this Agreement may not be assigned. The obligations of the Company under this
Agreement may not be assigned except to a successor to all or substantially all
of the business or assets of the Company or by operation of law. In the event of
your death, all future payments hereunder will be made to your estate or
designated beneficiary.

                                      WEBMD CORPORATION

                                      By /s/ Charles A. Mele
                                         --------------------------------------
                                         Name:   Charles A. Mele
                                         Title:  Executive Vice President --
                                                      Co-General Counsel

Accepted and Agreed:

 /s/ Jeffrey T. Arnold
-------------------------
Jeffrey T. Arnold

Dated: October 11, 2000

                                       7

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