<PAGE>

                                                                   EXHIBIT 10.22

                             SECURED PROMISSORY NOTE

$12,000,000               PALO ALTO, CALIFORNIA               DECEMBER 28, 2005

     FOR VALUE RECEIVED, ATHENAHEALTH, INC., a Delaware corporation ("Maker")
promises to pay to the order of ORIX VENTURE FINANCE LLC, a Delaware limited
liability company ("ORIX"), at 1177 Avenue of the Americas, 5th Floor, New York,
NY 10036, or at such other address as the holder of this Note shall direct, the
principal sum of TWELVE MILLION DOLLARS ($12,000,000).

     The principal of this Note shall be paid as follows: 30 equal monthly
payments of $400,000 each, commencing FEBRUARY 1, 2008 and continuing on the
first day of each succeeding month until JULY 1, 2010 (the "Maturity Date"), on
which date the entire unpaid principal balance of this Note, plus all accrued
and unpaid interest shall be due and payable.

     This Note is executed and delivered pursuant to that certain Loan and
Security Agreement among Maker, and ORIX of even date (as amended, supplemented
or otherwise modified from time to time, the "Loan Agreement"). (Capitalized
terms used herein, which are not defined, shall have the meanings set forth in
the Loan Agreement.) This Note is subject to, and entitled to all provisions and
benefits of, the Loan Agreement, including without limitation acceleration of
the maturity of this Note as provided in the Loan Agreement. This Note is
secured by the Loan Agreement and all other present and future security
agreements between Maker and ORIX. Nothing herein shall be deemed to limit any
of the terms or provisions of the Loan Agreement or any other present or future
document, instrument or agreement, between Maker and ORIX, and all of ORIX's
rights and remedies hereunder and thereunder are cumulative. Prepayment of the
principal of this Note is subject to the provisions of the Loan Agreement.

     This Note shall bear interest on the unpaid principal balance hereof from
time to time outstanding during each month at an interest rate equal to the
Prime Rate in effect on the last day of such month, plus 3.00% per annum.
Interest shall be calculated on the basis of a 360-day year for the actual
number of days elapsed. "Prime Rate" has the meaning set forth in Section 7 of
the Loan Agreement. The interest rate applicable to this Note shall increase as
provided in Section 6.2 of the Loan Agreement following an Event of Default.

     Accrued interest on this Note shall be payable monthly, within five days
after the end of each month. Any accrued interest not paid when due shall bear
interest at the same rate as the principal hereunder.

     Principal of and interest on this Note shall be payable in lawful money of
the United States of America by wire transfer to such account as ORIX shall
designate to the Maker from time to time. If a payment hereunder becomes due and
payable on a day which is not a Business Day, the due date thereof shall be
extended to the next succeeding Business Day, and interest shall be payable
thereon during such extension.

     ORIX and Maker intend to contract in strict compliance with applicable
usury law from time to time in effect. In furtherance thereof such Persons
stipulate and agree that none of the terms and provisions contained in the Loan
Agreement shall ever be construed to create a contract to pay, for the use,
forbearance or detention of money, interest in excess of the maximum amount of
interest permitted to be charged by applicable law from time to time in effect.
Neither the Maker nor any present or future guarantors, endorsers, or other
Persons hereafter becoming liable for payment of any Obligation shall ever be
liable for unearned interest


                                      -1-

<PAGE>

                                                         Secured Promissory Note

thereon or shall ever be required to pay interest thereon in excess of the
maximum amount that may be lawfully charged under applicable law from time to
time in effect, and the provisions of this paragraph shall control over all
other provisions of the Loan Agreement which may be in conflict herewith. ORIX
expressly disavows any intention to charge or collect excessive unearned
interest or finance charges in the event the maturity of any Obligation is
accelerated. If (a) the maturity of any Obligation is accelerated for any
reason, (b) any Obligation is prepaid and as a result any amounts held to
constitute interest are determined to be in excess of the legal maximum, or (c)
ORIX or any other holder of any or all of the Obligations shall otherwise
collect amounts which are determined to constitute interest which would
otherwise increase the interest on any or all of the Obligations to an amount in
excess of that permitted to be charged by applicable law then in effect, then
all sums determined to constitute interest in excess of such legal limit shall,
without penalty, be promptly applied to reduce the then outstanding principal of
the related Obligations or, at ORIX's or such holder's option, promptly returned
to the Maker upon such determination. In determining whether or not the interest
paid or payable, under any specific circumstance, exceeds the maximum amount
permitted under applicable law, ORIX and the Maker (and any other payors
thereof) shall to the greatest extent permitted under applicable law, (i)
characterize any non-principal payment as an expense, fee or premium rather than
as interest, (ii) exclude voluntary prepayments and the effects thereof, and
(iii) amortize, prorate, allocate, and spread the total amount of interest
through the entire contemplated term of this Note in accordance with the amount
outstanding from time to time thereunder and the maximum legal rate of interest
from time to time in effect under applicable law in order to lawfully charge the
maximum amount of interest permitted under applicable law.

     In the event any payment of principal or interest on this Note is not paid
in full within three Business Days after the date due, or if any other Event of
Default (as defined in the Loan Agreement) occurs and is continuing, ORIX may,
at its option, at any time thereafter, without limiting its other rights and
remedies, declare the entire unpaid principal balance of this Note plus all
accrued interest to be immediately due and payable, without notice or demand.
Without limiting the foregoing, if any payment of principal, accrued interest or
any other payment hereunder is not made within five Business Days after the date
due, Maker shall pay ORIX a late payment fee equal to 5% of the amount of such
late payment. In addition, if the entire balance of this Note and all accrued
and unpaid interest, and all other monetary Obligations are not paid in full by
the Maturity Date, Maker shall pay ORIX a late charge of $50,000. The acceptance
of any installment of principal or interest by ORIX after the time when it
becomes due, as herein specified, shall not be held to establish a custom, or to
waive any rights of ORIX to enforce payment when due of any further installments
or any other rights, nor shall any failure or delay to exercise any rights be
held to waive the same.

     All payments hereunder are to be applied first to reasonable costs and fees
referred to herein, second to the payment of accrued interest and the remaining
balance to the payment of principal. Any principal prepayment hereunder shall be
applied against principal payments in the inverse order of maturity. ORIX shall
have the continuing and exclusive right to apply or reverse and reapply any and
all payments hereunder.

     Maker agrees to pay all reasonable costs and expenses (including without
limitation reasonable attorney's fees) incurred by ORIX in connection with or
related to this Note, or its enforcement, whether or not suit be brought. Maker
hereby waives presentment, demand for payment, notice of dishonor, notice of
nonpayment, protest, notice of protest, and any and all other notices and
demands in connection with the delivery, acceptance, performance, default, or
enforcement of this Note, and Maker hereby waives the benefits of any statute of
limitations with respect to any action to enforce, or otherwise related to, this
Note. In the event any one or more


                                      -2-

<PAGE>

                                                         Secured Promissory Note

of the provisions of this Note shall for any reason be held to be invalid,
illegal or unenforceable, the same shall not affect any other provision of this
Note and the remaining provisions of this Note shall remain in full force and
effect. No waiver or modification of any of the terms or provisions of this Note
shall be valid or binding unless set forth in a writing signed by a duly
authorized officer of ORIX and Maker, and then only to the extent therein
specifically set forth. If more than one person executes this Note, their
obligations hereunder shall be joint and several. This Note and all acts,
transactions, disputes and controversies arising hereunder or relating hereto,
and all rights and obligations of ORIX and Maker shall be governed by, and
construed in accordance with the internal laws (and not the conflict of laws
rules) of the State of California. Maker (i) agrees that all actions and
proceedings relating directly or indirectly to this Note shall, at ORIX's
option, be litigated in courts located within California, and that the exclusive
venue therefor shall be Santa Clara County; (ii) consents to the jurisdiction
and venue of any such court and consents to service of process in any such
action or proceeding by personal delivery or any other method permitted by law;
and (iii) waives any and all rights Maker may have to object to the jurisdiction
of any such court, or to transfer or change the venue of any such action or
proceeding.

     ORIX AND MAKER EACH HEREBY WAIVE THE RIGHT TO TRIAL BY JURY IN ANY ACTION
OR PROCEEDING BASED UPON, ARISING OUT OF, OR IN ANY WAY RELATING TO: (I) THIS
NOTE; OR (II) ANY OTHER PRESENT OR FUTURE INSTRUMENT OR AGREEMENT BETWEEN ORIX
AND MAKER; OR (III) ANY CONDUCT, ACTS OR OMISSIONS OF ORIX OR MAKER OR ANY OF
THEIR DIRECTORS, OFFICERS, EMPLOYEES, AGENTS, ATTORNEYS OR ANY OTHER PERSONS
AFFILIATED WITH ORIX OR MAKER; IN EACH OF THE FOREGOING CASES, WHETHER SOUNDING
IN CONTRACT OR TORT OR OTHERWISE.


                                      -3-

<PAGE>

                                        ATHENAHEALTH, INC.,
                                        a Delaware corporation


                                        By /s/ Jonathan Bush
                                           -------------------------------------
                                        Title President and CEO

                    Signature Page--Secured Promissory Note
<PAGE>



                             SECURED PROMISSORY NOTE

$2,000,000                PALO ALTO, CALIFORNIA               SEPTEMBER 21, 2006

     FOR VALUE RECEIVED, ATHENAHEALTH, INC., a Delaware corporation ("Maker")
promises to pay to the order of ORIX VENTURE FINANCE LLC, a Delaware limited
liability company ("ORIX"), at 1177 Avenue of the Americas, 5th Floor, New York,
NY 10036, or at such other address as the holder of this Note shall direct, the
principal sum of TWO MILLION DOLLARS ($2,000,000), or such lesser amount as
shall represent the unpaid principal balance of Term Loan No. 2 under the Loan
Agreement referred to below.

     The principal of this Note shall be paid as follows: 30 equal monthly
payments of principal, each in an amount equal to 1/30th of the total principal
balance of Term Loan No. 2 disbursed to Maker under the Loan Agreement, such
principal payments to commence on FEBRUARY 1, 2008 and continue on the first day
of each succeeding month until JULY 1, 2010 (the "Maturity Date"), on which date
the entire unpaid principal balance of this Note, plus all accrued and unpaid
interest shall be due and payable.

     This Note is executed and delivered pursuant to that certain Loan and
Security Agreement among Maker, and ORIX dated December 28, 2005 (as amended,
supplemented or otherwise modified from time to time, the "Loan Agreement").
(Capitalized terms used herein, which are not defined, shall have the meanings
set forth in the Loan Agreement.) This Note is subject to, and entitled to all
provisions and benefits of, the Loan Agreement, including without limitation
acceleration of the maturity of this Note as provided in the Loan Agreement.
This Note is secured by the Loan Agreement and all other present and future
security agreements between Maker and ORIX. Nothing herein shall be deemed to
limit any of the terms or provisions of the Loan Agreement or any other present
or future document, instrument or agreement, between Maker and ORIX, and all of
ORIX's rights and remedies hereunder and thereunder are cumulative. Prepayment
of the principal of this Note is subject to the provisions of the Loan
Agreement.

     This Note shall bear interest on the unpaid principal balance hereof from
time to time outstanding during each month at an interest rate equal to the
Prime Rate in effect on the last day of such month, plus 3.00% per annum.
Interest shall be calculated on the basis of a 360-day year for the actual
number of days elapsed. "Prime Rate" has the meaning set forth in Section 7 of
the Loan Agreement. The interest rate applicable to this Note shall increase as
provided in Section 6.2 of the Loan Agreement following an Event of Default.

     Accrued interest on this Note shall be payable monthly, within five days
after the end of each month. Any accrued interest not paid when due shall bear
interest at the same rate as the principal hereunder.

     Principal of and interest on this Note shall be payable in lawful money of
the United States of America by wire transfer to such account as ORIX shall
designate to the Maker from time to time. If a payment hereunder becomes due and
payable on a day which is not a Business Day, the due date thereof shall be
extended to the next succeeding Business Day, and interest shall be payable
thereon during such extension.

     ORIX and Maker intend to contract in strict compliance with applicable
usury law from time to time in effect. In furtherance thereof such Persons
stipulate and agree that none of the terms and provisions contained in the Loan
Agreement shall ever be construed to create a contract to pay, for the use,
forbearance or detention of money, interest in excess of the


                                       -1-

<PAGE>

                                                         Secured Promissory Note

maximum amount of interest permitted to be charged by applicable law from time
to time in effect. Neither the Maker nor any present or future guarantors,
endorsers, or other Persons hereafter becoming liable for payment of any
Obligation shall ever be liable for unearned interest thereon or shall ever be
required to pay interest thereon in excess of the maximum amount that may be
lawfully charged under applicable law from time to time in effect, and the
provisions of this paragraph shall control over all other provisions of the Loan
Agreement which may be in conflict herewith. ORIX expressly disavows any
intention to charge or collect excessive unearned interest or finance charges in
the event the maturity of any Obligation is accelerated. If (a) the maturity of
any Obligation is accelerated for any reason, (b) any Obligation is prepaid and
as a result any amounts held to constitute interest are determined to be in
excess of the legal maximum, or (c) ORIX or any other holder of any or all of
the Obligations shall otherwise collect amounts which are determined to
constitute interest which would otherwise increase the interest on any or all of
the Obligations to an amount in excess of that permitted to be charged by
applicable law then in effect, then all sums determined to constitute interest
in excess of such legal limit shall, without penalty, be promptly applied to
reduce the then outstanding principal of the related Obligations or, at ORIX's
or such holder's option, promptly returned to the Maker upon such determination.
In determining whether or not the interest paid or payable, under any specific
circumstance, exceeds the maximum amount permitted under applicable law, ORIX
and the Maker (and any other payors thereof) shall to the greatest extent
permitted under applicable law, (i) characterize any non-principal payment as an
expense, fee or premium rather than as interest, (ii) exclude voluntary
prepayments and the effects thereof, and (iii) amortize, prorate, allocate, and
spread the total amount of interest through the entire contemplated term of this
Note in accordance with the amount outstanding from time to time thereunder and
the maximum legal rate of interest from time to time in effect under applicable
law in order to lawfully charge the maximum amount of interest permitted under
applicable law.

     In the event any payment of principal or interest on this Note is not paid
in full within three Business Days after the date due, or if any other Event of
Default (as defined in the Loan Agreement) occurs and is continuing, ORIX may,
at its option, at any time thereafter, without limiting its other rights and
remedies, declare the entire unpaid principal balance of this Note plus all
accrued interest to be immediately due and payable, without notice or demand.
Without limiting the foregoing, if any payment of principal, accrued interest or
any other payment hereunder is not made within five Business Days after the date
due, Maker shall pay ORIX a late payment fee equal to 5% of the amount of such
late payment. In addition, if the entire balance of this Note and all accrued
and unpaid interest, and all other monetary Obligations are not paid in full by
the Maturity Date, Maker shall pay ORIX a late charge of $50,000. The acceptance
of any installment of principal or interest by ORIX after the time when it
becomes due, as herein specified, shall not be held to establish a custom, or to
waive any rights of ORIX to enforce payment when due of any further installments
or any other rights, nor shall any failure or delay to exercise any rights be
held to waive the same.

     All payments hereunder are to be applied first to reasonable costs and fees
referred to herein, second to the payment of accrued interest and the remaining
balance to the payment of principal. Any principal prepayment hereunder shall be
applied against principal payments in the inverse order of maturity. ORIX shall
have the continuing and exclusive right to apply or reverse and reapply any and
all payments hereunder.

     Maker agrees to pay all reasonable costs and expenses (including without
limitation reasonable attorney's fees) incurred by ORIX in connection with or
related to this Note, or its enforcement, whether or not suit be brought. Maker
hereby waives presentment, demand for payment, notice of dishonor, notice of
nonpayment, protest, notice of protest, and any and all


                                       -2-

<PAGE>

                                                         Secured Promissory Note

other notices and demands in connection with the delivery, acceptance,
performance, default, or enforcement of this Note, and Maker hereby waives the
benefits of any statute of limitations with respect to any action to enforce, or
otherwise related to, this Note. In the event any one or more of the provisions
of this Note shall for any reason be held to be invalid, illegal or
unenforceable, the same shall not affect any other provision of this Note and
the remaining provisions of this Note shall remain in full force and effect. No
waiver or modification of any of the terms or provisions of this Note shall be
valid or binding unless set forth in a writing signed by a duly authorized
officer of ORIX and Maker, and then only to the extent therein specifically set
forth. If more than one person executes this Note, their obligations hereunder
shall be joint and several. This Note and all acts, transactions, disputes and
controversies arising hereunder or relating hereto, and all rights and
obligations of ORIX and Maker shall be governed by, and construed in accordance
with the internal laws (and not the conflict of laws rules) of the State of
California. Maker (i) agrees that all actions and proceedings relating directly
or indirectly to this Note shall, at ORIX's option, be litigated in courts
located within California, and that the exclusive venue therefor shall be Santa
Clara County; (ii) consents to the jurisdiction and venue of any such court and
consents to service of process in any such action or proceeding by personal
delivery or any other method permitted by law; and (iii) waives any and all
rights Maker may have to object to the jurisdiction of any such court, or to
transfer or change the venue of any such action or proceeding.

     ORIX AND MAKER EACH HEREBY WAIVE THE RIGHT TO TRIAL BY JURY IN ANY ACTION
OR PROCEEDING BASED UPON, ARISING OUT OF, OR IN ANY WAY RELATING TO: (I) THIS
NOTE; OR (II) ANY OTHER PRESENT OR FUTURE INSTRUMENT OR AGREEMENT BETWEEN ORIX
AND MAKER; OR (III) ANY CONDUCT, ACTS OR OMISSIONS OF ORIX OR MAKER OR ANY OF
THEIR DIRECTORS, OFFICERS, EMPLOYEES, AGENTS, ATTORNEYS OR ANY OTHER PERSONS
AFFILIATED WITH ORIX OR MAKER; IN EACH OF THE FOREGOING CASES, WHETHER SOUNDING
IN CONTRACT OR TORT OR OTHERWISE.

                                        ATHENAHEALTH, INC.,
                                        a Delaware Corporation


                                        By: /s/ Jonathan Bush
                                            ------------------------------------
                                        Title: Jonathan Bush President & CEO


                                       -3-
<PAGE>

                             SECURED PROMISSORY NOTE

$3,000,000                    Palo Alto, California                 June 8, 2007

     FOR VALUE RECEIVED, ATHENAHEALTH, INC., a Delaware corporation ("Maker")
promises to pay to the order of ORIX VENTURE FINANCE LLC, a Delaware limited
liability company ("ORIX"), at 245 Park Avenue, 19th Floor, New York, NY 10167,
or at such other address as the holder of this Note shall direct, the principal
sum of THREE MILLION Dollars ($3,000,000), or such lesser amount as shall
represent the unpaid principal balance of Term Loan No. 3 under the Loan
Agreement referred to below.

     The principal of this Note shall be paid as follows: 30 equal monthly
payments of principal, each in an amount equal to $100,000, such principal
payments to commence on February 1, 2008 and continue on the first day of each
succeeding month until July 1, 2010 (the "Maturity Date"), on which date the
entire unpaid principal balance of this Note, plus all accrued and unpaid
interest shall be due and payable.

     This Note is executed and delivered pursuant to that certain Loan and
Security Agreement among Maker, and ORIX dated December 28, 2005 (as amended,
supplemented or otherwise modified from time to time, the "Loan Agreement").
(Capitalized terms used herein, which are not defined, shall have the meanings
set forth in the Loan Agreement.) This Note is subject to, and entitled to all
provisions and benefits of, the Loan Agreement, including without limitation
acceleration of the maturity of this Note as provided in the Loan Agreement.
This Note is secured by the Loan Agreement and all other present and future
security agreements between Maker and ORIX. Nothing herein shall be deemed to
limit any of the terms or provisions of the Loan Agreement or any other present
or future document, instrument or agreement, between Maker and ORIX, and all of
ORIX's rights and remedies hereunder and thereunder are cumulative. Prepayment
of the principal off this Note is subject to the provisions of the Loan
Agreement.

     Subject to the last sentence of Section 6.2 of the Loan Agreement, this
Note shall bear interest on the unpaid principal balance hereof from time to
time outstanding during each month at the interest rate applicable to Term Loan
No. 3 as set forth in Section 2 of the Schedule to the Loan Agreement. Interest
shall be calculated on the basis of a 360-day year for the actual number of days
elapsed. "Prime Rate" has the meaning set forth in Section 7 of the Loan
Agreement. The interest rate applicable to this Note shall increase as provided
in Section 6.2 of the Loan Agreement following an Event of Default.

     Accrued interest on this Note shall be payable monthly, within five days
after the end of each month. Any accrued interest not paid when due shall bear
interest at the same rate as the principal hereunder.

     Principal of and interest on this Note shall be payable in lawful money of
the United States of America by wire transfer to such account as ORIX shall
designate to the Maker from time to time. If a payment hereunder becomes due and
payable on a day which is not a Business Day, the due date thereof shall be
extended to the next succeeding Business Day, and interest shall be payable
thereon during such extension.

<PAGE>

     ORIX and Maker intend to contract in strict compliance with applicable
usury law from time to time in effect. In furtherance thereof such Persons
stipulate and agree that none of the terms and provisions contained in the Loan
Agreement shall ever be construed to create a contract to pay, for the use,
forbearance or detention of money, interest in excess of the maximum amount of
interest permitted to be charged by applicable law from time to time in effect.
Neither the Maker nor any present or future guarantors, endorsers, or other
Persons hereafter becoming liable for payment of any Obligation shall ever be
liable for unearned interest thereon or shall ever be required to pay interest
thereon in excess of the maximum amount that may be lawfully charged under
applicable law from time to time in effect, and the provisions of this paragraph
shall control over all other provisions of the Loan Agreement which may be in
conflict herewith. ORIX expressly disavows any intention to charge or collect
excessive unearned interest or finance charges in the event the maturity of any
Obligation is accelerated. If (a) the maturity of any Obligation is accelerated
for any reason, (b) any Obligation is prepaid and as a result any amounts held
to constitute interest are determined to be in excess of the legal maximum, or
(c) ORIX or any other holder of any or all of the Obligations shall otherwise
collect amounts which are determined to constitute interest which would
otherwise increase the interest on any or all of the Obligations to an amount in
excess of that permitted to be charged by applicable law then in effect, then
all sums determined to constitute interest in excess of such legal limit shall,
without penalty, be promptly applied to reduce the then outstanding principal of
the related Obligations or, at ORIX's or such holder's option, promptly returned
to the Maker upon such determination. In determining whether or not the interest
paid or payable, under any specific circumstance, exceeds the maximum amount
permitted under applicable law, ORIX and the Maker (and any other payors
thereof) shall to the greatest extent permitted under applicable law, (i)
characterize any non-principal payment as an expense, fee or premium rather than
as interest, (ii) exclude voluntary prepayments and the effects thereof, and
(iii) amortize, prorate, allocate, and spread the total amount of interest
through the entire contemplated term off this Note in accordance with the amount
outstanding from time to time thereunder and the maximum legal rate of interest
from time to time in effect under applicable law in order to lawfully charge the
maximum amount of interest permitted under applicable law.

     In the event any payment off principal or interest on this Note is not paid
in full within three Business Days after the date due, or if any other Event of
Default (as defined in the Loan Agreement) occurs and is continuing, ORIX may,
at its option, at any time thereafter, without limiting its other rights and
remedies, declare the entire unpaid principal balance of this .Note plus all
accrued interest to be immediately due and payable, without notice or demand.
Without limiting the foregoing, if any payment of principal, accrued interest or
any other payment hereunder is not made within five Business Days after the date
due, Maker shall pay ORIX a late payment fee equal to 5% of the amount of such
late payment. In addition, if the entire balance of this Note and all accrued
and unpaid interest, and all other monetary Obligations are not paid in full by
the Maturity Date, Maker shall pay ORIX a late charge of $50,000. The acceptance
of any installment of principal or interest by ORIX after the time when it
becomes due, as herein specified, shall not be held to establish a custom, or to
waive any rights of ORIX to enforce payment when due of any further installments
or any other rights, nor shall any failure or delay to exercise any rights be
held to waive the same.

     All payments hereunder are to be applied first to reasonable costs and fees
referred to herein, second to the payment of accrued interest and the remaining
balance to the payment of


                                        2

<PAGE>

principal. Any principal prepayment hereunder shall be applied against principal
payments in the inverse order of maturity. ORIX shall have the continuing and
exclusive right to apply or reverse and reapply any and all payments hereunder.

     Maker agrees to pay all reasonable costs and expenses (including without
limitation reasonable attorney's fees) incurred by ORIX in connection with or
related to this Note, or its enforcement, whether or not suit be brought. Maker
hereby waives presentment, demand for payment, notice of dishonor, notice of
nonpayment, protest, notice of protest, and any and all other notices and
demands in connection with the delivery, acceptance, performance, default, or
enforcement of this Note, and Maker hereby waives the benefits of any statute of
limitations with respect to any action to enforce, or otherwise related to, this
Note. In the event any one or more of the provisions of this Note shall for any
reason be held to be invalid, illegal or unenforceable, the same shall not
affect any other provision of this Note and the remaining provisions of this
Note shall remain in full force and effect. No waiver or modification of any of
the terms or provisions of this Note shall be valid or binding unless set forth
in a writing signed by a duly authorized officer of ORIX and Maker, and then
only to the extent therein specifically set forth. If more than one person
executes this Note, their obligations hereunder shall be joint and several. This
Note and all acts, transactions, disputes and controversies arising hereunder or
relating hereto, and all rights and obligations of ORIX and Maker shall be
governed by, and construed in accordance with the internal laws (and not the
conflict of laws rules) of the State of California. Maker (i) agrees that all
actions and proceedings relating directly or indirectly to this Note shall, at
ORIX's option, be litigated in courts located within California, and that the
exclusive venue therefor shall be Santa Clara County; (ii) consents to the
jurisdiction and venue of any such court and consents to service of process in
any such action or proceeding by personal delivery or any other method permitted
by law; and (iii) waives any and all rights Maker may have to object to the
jurisdiction of any such court, or to transfer or change the venue of any such
action or proceeding. Section 8.9 of the Loan Agreement is incorporated herein
by this reference as though fully -set forth herein, and applies to this Note
mutatis mutandis.

     ORIX AND MAKER EACH HEREBY WAIVE THE RIGHT TO TRIAL BY JURY IN ANY ACTION
OR PROCEEDING BASED UPON, ARISING OUT OF, OR IN ANY WAY RELATING TO: (i) THIS
NOTE; OR (ii) ANY OTHER PRESENT OR FUTURE INSTRUMENT OR AGREEMENT BETWEEN ORIX
AND MAKER; OR (iii) ANY CONDUCT, ACTS OR OMISSIONS OF ORIX OR MAKER OR ANY OF
THEIR DIRECTORS, OFFICERS, EMPLOYEES, AGENTS, ATTORNEYS OR ANY OTHER PERSONS
AFFILIATED WITH ORIX OR MAKER; IN EACH OF THE FOREGOING CASES, WHETHER SOUNDING
IN CONTRACT OR TORT OR OTHERWISE.

                                        ATHENAHEALTH, INC.,
                                        a Delaware corporation


                                        By: /s/ Jonathan Bush
                                            ------------------------------------
                                            Jonathan Bush, President & CEO


                                        3