Document:

Exhibit 4.1

                                                                  Execution Copy

THE ISSUANCE OF THIS WARRANT AND THE OFFER AND SALE OF THE SHARES OF COMMON
STOCK ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
1933 (THE "ACT") NOR UNDER ANY STATE SECURITIES LAW AND THIS WARRANT AND ANY
SUCH SHARES OF COMMON STOCK MAY NOT BE PLEDGED, SOLD, ASSIGNED OR OTHERWISE
TRANSFERRED UNTIL A (1) REGISTRATION STATEMENT UNDER THE ACT AND ANY APPLICABLE
STATE SECURITIES LAW HAS BECOME EFFECTIVE WITH RESPECT THERETO, OR (2) RECEIPT
BY THE COMPANY OF AN OPINION OF COUNSEL ACCEPTABLE TO THE COMPANY (IF SO
REQUESTED) TO THE EFFECT THAT REGISTRATION UNDER THE ACT OR APPLICABLE STATE
SECURITIES LAW IS NOT REQUIRED IN CONNECTION WITH THE PROPOSED TRANSFER.

           Void after 5:00 p.m. Eastern Standard Time, on May 1, 2008.
           Warrant to Purchase 215,909 Shares of Common Stock.

                        WARRANT TO PURCHASE COMMON STOCK

                                       OF

                             ALLION HEALTHCARE, INC.

           This is to certify that, for good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, Darin A. Peterson
("HOLDER") is entitled to purchase, subject to the provisions of this Warrant,
from Allion Healthcare, Inc., a Delaware corporation ("COMPANY"), TWO HUNDRED
FIFTEEN THOUSAND NINE HUNDRED NINE (215,909) fully paid, validly issued and
nonassessable shares of Common Stock, $0.01 par value per share, of the Company
("COMMON STOCK") at a price initially set at eleven Dollars ($11.00) per share
at any time or from time to time during the period from the date hereof to
expiration, but not later than 5:00 p.m. Eastern Standard Time, on May 1, 2008.
The number of shares of Common Stock to be received upon the exercise of this
Warrant and the price to be paid for each share of Common Stock may be adjusted
from time to time as hereinafter set forth. The shares of Common Stock
deliverable upon such exercise, and as adjusted from time to time, are
hereinafter sometimes referred to as "WARRANT SHARES" and the exercise price of
a share of Common Stock in effect at any time and as adjusted from time to time
is hereinafter sometimes referred to as the "EXERCISE PRICE".

               (a) EXERCISE OF WARRANT.

                   (1)  This Warrant may be exercised in whole or in part at any
                        time or from time to time on or after the date hereof
                        and until 5:00 p.m Eastern Standard Time on May 1, 2008;
                        provided, however, that if either such day is a day on
                        which banking institutions in the State of New York are

<PAGE>

                        authorized by law to close, then on the next succeeding
                        day which shall not be such a day. This Warrant may be
                        exercised by presentation and surrender hereof to the
                        Company at its principal office, or at the office of its
                        stock transfer agent, if any, with the Purchase Form
                        annexed hereto duly executed and accompanied by payment
                        of the Exercise Price for the number of Warrant Shares
                        specified in such form. As soon as practicable after
                        each such exercise of this Warrant, but not later than
                        seven (7) days from the date of such exercise, the
                        Company shall issue and deliver to the Holder a
                        certificate for the Warrant Shares issuable upon such
                        exercise, registered in the name of the Holder or its
                        designee. If this Warrant should be exercised in part
                        only, the Company shall, upon surrender of this Warrant
                        for cancellation, execute and deliver a new Warrant
                        evidencing the rights of the Holder thereof to purchase
                        the balance of the Warrant Shares purchasable
                        thereunder. Upon receipt by the Company of this Warrant
                        at its office, or by the stock transfer agent of the
                        Company, if any, at its office, in proper form for
                        exercise together with payment in full of the exercise
                        price for the Warrant Shares to be purchased, the Holder
                        shall be deemed to be the holder of record of the shares
                        of Common Stock issuable upon such exercise,
                        notwithstanding that the stock transfer books of the
                        Company shall then be closed or that certificates
                        representing such shares of Common Stock shall not then
                        be physically delivered to the Holder.

                   (2)  In lieu of delivering the Exercise Price in cash or
                        check, the Holder may elect to receive shares equal to
                        the value of the Warrant or portion thereof being
                        exercised ("NET ISSUE EXERCISE"). If the Holder wishes
                        to elect the Net Issue Exercise, the Holder shall notify
                        the Company of its election in writing at the time it
                        delivers the Purchase Form to the Company. In the event
                        the Holder shall elect Net Issue Exercise, the Holder
                        shall receive the number of shares of Common Stock equal
                        to the product of (a) the number of shares of Common
                        Stock purchasable under the Warrant, or portion thereof
                        being exercised, and (b) the current market value, as
                        defined in paragraph (c) below, of one share of Common
                        Stock minus the Exercise Price, divided by (c) the
                        current market value, as defined in paragraph (c) below,
                        of one share of Common Stock.

           (b) RESERVATION OF SHARES. The Company shall at all times reserve for
               issuance and/or delivery upon exercise of this Warrant such
               number of shares of its Common Stock as shall be required for
               issuance and delivery upon exercise of this Warrant.

           (c) FRACTIONAL SHARES. No fractional shares or scrip representing
               fractional shares shall be issued upon the exercise of this
               Warrant. With respect to any fraction of a share called for upon
               any exercise hereof, the Company shall pay to the Holder an
               amount in cash equal to such fraction multiplied by the current
               market value of a share, determined as follows:

                                      -2-
<PAGE>

                   (1)  If the Common Stock is listed on a national securities
                        exchange or admitted to unlisted trading privileges on
                        such exchange or listed for trading on the NASDAQ
                        system, the current market value shall be the last
                        reported sale price of the Common Stock on such exchange
                        or system on the last business day prior to the date of
                        exercise of this Warrant or if no such sale is made on
                        such day, the mean of the last reported bid and asked
                        prices for such day on such exchange or system; or

                   (2)  If the Common Stock is not so listed or admitted to
                        unlisted trading privileges, the current market value
                        shall be the mean of the last reported bid and asked
                        prices reported by the National Quotation Bureau, Inc.
                        on the last business day prior to the date of the
                        exercise of this Warrant; or

                   (3)  If the Common Stock is not so listed or admitted to
                        unlisted trading privileges and bid and asked prices are
                        not so reported, the current market value of a share of
                        Common Stock shall be an amount, not less than book
                        value thereof as at the end of the most recent fiscal
                        year of the Company ending prior to the date of the
                        exercise of the Warrant, determined in such reasonable
                        manner as may be prescribed by the Board of Directors of
                        the Company.

           (d) EXCHANGE, TRANSFER, ASSIGNMENT OR LOSS OF WARRANT. Subject to the
               restrictions noted at the beginning of this Warrant, this Warrant
               is exchangeable, without expense, at the option of the Holder,
               upon presentation and surrender hereof to the Company or at the
               office of its stock transfer agent, if any, for other warrants of
               different denominations entitling the holder thereof to purchase
               in the aggregate the same number of shares of Common Stock
               purchasable hereunder. Upon surrender of this Warrant to the
               Company at its principal office or at the office of its stock
               transfer agent, if any, with the Assignment Form annexed hereto
               duly executed and funds sufficient to pay any transfer tax, the
               Company shall, without charge, execute and deliver a new Warrant
               in the name of the assignee named in such instrument of
               assignment and this Warrant shall promptly be cancelled. This
               Warrant may be divided or combined with other warrants which
               carry the same rights upon presentation hereof at the principal
               office of the Company or at the office of its stock transfer
               agent, if any, together with a written notice specifying the
               names and denominations in which new Warrants are to be issued
               and signed by the Holder hereof. The term "WARRANT" as used
               herein includes any Warrants into which this Warrant may be
               divided ------- or exchanged. Upon receipt by the Company of
               evidence satisfactory to it of the loss, theft, destruction or
               mutilation of this Warrant, and (in the case of loss; theft or
               destruction) of reasonably satisfactory indemnification, and upon
               surrender and cancellation of this Warrant, if mutilated, the
               Company will execute and deliver a new Warrant of like tenor and
               date. Any such new Warrant executed and delivered shall
               constitute an additional contractual obligation on the part of
               the Company, whether or not this Warrant so lost, stolen,
               destroyed, or mutilated shall be at any time enforceable by
               anyone.

                                      -3-
<PAGE>

           (e) RIGHTS OF THE HOLDER. The Holder shall not, by virtue hereof, be
               entitled to any rights of a shareholder in the Company, either at
               law or equity, and the rights of the Holder are limited to those
               expressed in the Warrant and are not enforceable against the
               Company except to the extent set forth herein.

           (f) ANTI-DILUTION AND ADJUSTMENT' PROVISIONS. The Exercise Price in
               effect at any time and the number of securities purchasable upon
               the exercise of the Warrant shall be subject to adjustment from
               time to time upon the happening of certain events as follows:

                   (1)  In case the Company shall (i) declare a dividend or make
                        a distribution on its outstanding shares of Common Stock
                        in shares of Common Stock, (ii) subdivide or reclassify
                        its outstanding shares of Common Stock into a greater
                        number of shares, or (iii) combine or reclassify its
                        outstanding shares of Common Stock into a smaller number
                        of shares, the Exercise Price in effect at the time of
                        the record date for such dividend or distribution, or of
                        the effective date of such subdivision, combination or
                        reclassification shall be adjusted so that it shall
                        equal the price determined by multiplying the Exercise
                        Price by a fraction, the denominator of which shall be
                        the number of shares of Common Stock outstanding after
                        giving effect to such action, and the numerator of which
                        shall be the number of shares of Common Stock
                        outstanding immediately prior to such action. Such
                        adjustment shall be made successively whenever any event
                        listed above shall occur.

                   (2)  In case the Company shall fix a record date for the
                        issuance of rights or warrants to all holders of its
                        Common Stock entitling them to subscribe for or purchase
                        shares of Common Stock (or securities convertible into
                        Common Stock) at a price (the "SUBSCRIPTION PRICE") (or
                        having a conversion price per share) less than the
                        Exercise Price on such record date, the Exercise Price
                        shall be adjusted so that the same shall equal the price
                        determined by multiplying the Exercise Price in effect
                        immediately prior to the date of issuance by a fraction,
                        the numerator of which shall be the sum of the number of
                        shares outstanding on the record date mentioned above
                        and the number of additional shares of Common Stock
                        which the aggregate offering price of the total number
                        of shares of Common Stock so offered (or the aggregate
                        conversion price of the convertible securities so
                        offered) would purchase at the Exercise Price in effect
                        immediately prior to the date of such issuance, and the
                        denominator of which shall be the sum of the number of
                        shares of Common Stock outstanding on the record date
                        mentioned above and the number of additional shares of
                        Common Stock offered for subscription or purchase (or
                        into which the convertible securities so offered are
                        convertible). Such adjustment shall be made successively
                        whenever such rights or warrants are issued and shall
                        become effective immediately after the record date for
                        the determination of shareholders entitled to receive
                        such rights or warrants; and to the extent that shares
                        of Common Stock are not delivered (or

                                      -4-
<PAGE>

                        securities convertible into Common Stock are not
                        delivered) after the expiration of such rights or
                        warrants, the Exercise Price shall be readjusted to the
                        Exercise Price which would then be in effect had the
                        adjustments made upon the issuance of such rights or
                        warrants been made upon the basis of delivery of only
                        the number of shares of Common Stock (or securities
                        convertible into Common Stock) actually delivered.

                   (3)  In case the Company shall hereafter distribute to the
                        holders of its Common Stock evidences of its
                        indebtedness or assets (excluding cash dividends or
                        distributions and dividends or distributions referred to
                        in Subsection (1) above) or subscription rights or
                        warrants (excluding those referred to in Subsection (2)
                        above), then in each such case the Exercise Price in
                        effect thereafter shall be determined by multiplying the
                        Exercise Price in effect immediately prior thereto by a
                        fraction, the numerator of which shall be the total
                        number of shares of Common Stock outstanding multiplied
                        by the current market price per share of Common Stock
                        (as defined in Section (c) above), less the fair market
                        value (as determined by the Company's Board of
                        Directors) of said assets or evidences of indebtedness
                        so distributed or of such rights or warrants, and the
                        denominator of which shall be the total number of shares
                        of Common Stock outstanding multiplied by such current
                        market price per share of Common Stock. Such adjustment
                        shall be made successively whenever such a record date
                        is fixed. Such adjustment shall be made whenever any
                        such distribution is made and shall become effective
                        immediately after the record date for the determination
                        of shareholders entitled to receive such distribution.

                   (4)  Whenever the Exercise Price payable upon exercise of
                        each Warrant is adjusted pursuant to Subsections (1),
                        (2), and (3) above, the number of Shares purchasable
                        upon exercise of this Warrant shall simultaneously be
                        adjusted by multiplying the number of Shares initially
                        issuable upon exercise of this Warrant by the Exercise
                        Price in effect on the date hereof and dividing the
                        product so obtained by the Exercise Price, as adjusted.

                   (5)  In the case of the issuance of securities convertible
                        into or exchangeable for shares of Common Stock, the
                        aggregate consideration received therefor shall be
                        deemed to be the consideration received by the Company
                        for the issuance of such securities plus the additional
                        minimum consideration, if any, to be received by the
                        Company upon the conversion or exchange thereof the
                        consideration in each case to be determined in the same
                        manner as provided in clauses (A) and (B) of this
                        Subsection (5).

                   (6)  No adjustment in the Exercise Price shall be required
                        unless such adjustment would require an increase or
                        decrease of at least five cents ($0.05) in such price;
                        provided, however, that any adjustments which by reason
                        of this Subsection (6) are not required to

                                      -5-
<PAGE>

                        be made shall be carried forward and taken into account
                        in any subsequent adjustment required to be made
                        hereunder. All calculations under this Section (f) shall
                        be made to the nearest cent or to the nearest
                        one-hundredth of a share, as the case may be. Anything
                        in this Section (f) to the contrary notwithstanding, the
                        Company shall be entitled, but shall not be required, to
                        make such changes in the Exercise Price, in addition to
                        those required by this Section (f), as it shall
                        determine, in its sole discretion, to be advisable in
                        order that any dividend or distribution in shares of
                        Common Stock, or any subdivision, reclassification or
                        combination of Common Stock, hereafter made by the
                        Company shall not result in any federal income tax
                        liability to the holders of Common Stock or securities
                        convertible into Common Stock (including Warrants).

                   (7)  The Company may retain a firm of independent certified
                        public accountants selected by the Board of Directors
                        (who may be the regular accountants employed by the
                        Company) to make any computation required by this
                        Section (f), and a certificate signed by such firm shall
                        be conclusive evidence of the correctness of such
                        adjustment.

                   (8)  In the event that at any time, as a result of an
                        adjustment made pursuant to Subsection (1) above, the
                        Holder of this Warrant thereafter shall become entitled
                        to receive any shares of the Company, other than Common
                        Stock, thereafter the number of such other shares so
                        receivable upon exercise of this Warrant shall be
                        subject to adjustment from time to time in a manner and
                        on terms as nearly equivalent as practicable to the
                        provisions with respect to the Common Stock contained in
                        Subsections (1) to (6) inclusive above.

                   (9)  Irrespective of any adjustments in the Exercise Price or
                        the number or kind of shares purchasable upon exercise
                        of this Warrant, Warrants theretofore or thereafter
                        issued may continue to express the same price and number
                        and kind of shares as are stated in the similar Warrants
                        initially issuable pursuant to this Agreement.

           (g) OFFICER'S CERTIFICATE. Whenever the Exercise Price shall be
               adjusted as required by the provisions of Section (f), the
               Company shall promptly and in no event later than 20 days after
               the effective date of adjustment cause to be mailed by certified
               mail to each Holder at his last address appearing in the Warrant
               Register and shall forthwith file, in the custody of its
               Secretary or an assistant Secretary at its principal office and
               with its stock transfer agent, if any, an officer's certificate
               showing the adjusted Exercise Price determined as herein
               provided, setting forth in reasonable detail the facts requiring
               such adjustment, including a statement of the number of
               additional shares of Common Stock, if any, and such other facts
               as shall be necessary to show the reason for and the manner of
               computing such adjustment. Each such officer's certificate shall
               be made available at all reasonable times for inspection by the
               Holder or any holder of a Warrant executed and delivered pursuant
               to Section (a).

                                      -6-
<PAGE>

           (h) NOTICES TO WARRANT HOLDERS. So long as this Warrant shall be
               outstanding, (i) if the Company shall pay any dividend or make
               any distribution upon the Common Stock or (ii) if the Company
               shall offer to the holders of Common Stock for subscription or
               purchase by them any share of any class or any other rights or
               (iii) if any capital reorganization of the Company,
               reclassification of the capital stock of the Company,
               consolidation or merger of the Company with or into another
               corporation, sale, lease or transfer of all or substantially all
               of the property and assets of the Company to another corporation,
               or voluntary or involuntary dissolution, liquidation or winding
               up of the Company shall be effected, then in any such case, the
               Company shall cause to be mailed by certified mail to the Holder,
               at least fifteen days prior to the date specified in (x) or (y)
               below, as the case may be, a notice containing a brief
               description of the proposed action and stating the date on which
               (x) a record is to be taken for the purpose of such dividend,
               distribution or rights, or (y) such reclassification,
               reorganization, consolidation, merger, conveyance, lease,
               dissolution, liquidation or winding up is to take place and the
               date, if any is to be fixed, as of which the holders of Common
               Stock or other securities shall receive cash or other property
               deliverable upon such reclassification, reorganization,
               consolidation, merger, conveyance, dissolution, liquidation or
               winding up.

           (i) RECLASSIFICATION REORGANIZATION OR MERGER. In case of any
               reclassification, capital reorganization or other change of
               outstanding shares of Common Stock of the Company, or in case of
               any consolidation or merger of the Company with or into another
               corporation (other than a merger with a subsidiary in which
               merger the Company is the continuing corporation and which does
               not result in any reclassification, capital reorganization or
               other change or outstanding shares of Common Stock of the class
               issuable upon exercise of this Warrant) or in case of any sale,
               lease or conveyance to another corporation of the property of the
               Company as an entirety, the Company shall, as a condition
               precedent to such transaction, cause effective provisions to be
               made so that the Holder shall have the right thereafter by
               exercising this Warrant at any time prior to the expiration of
               the Warrant, to purchase the kind and amount of shares of stock
               and other securities and property receivable upon such
               reclassification, capital reorganization and other change,
               consolidation, merger, sale or conveyance by a holder of the
               number of shares of Common Stock which might have been purchased
               upon exercise of this Warrant immediately prior to such
               reclassification, change, consolidation, merger, sale or
               conveyance. Any such provision shall include provision for
               adjustments which shall be as nearly equivalent as may be
               practicable to the adjustments provided for in this Warrant. The
               foregoing provisions of this Section (i) shall similarly apply to
               successive reclassifications, capital reorganizations and changes
               of shares of Common Stock and to successive consolidations,
               mergers, sales or conveyances. In the event that in connection
               with any such capital reorganization or reclassification,
               consolidation, merger, sale or conveyance, additional shares of
               Common Stock shall be issued in exchange, conversion,
               substitution or payment, in whole or in part, for a security of
               the Company other than Common Stock, any such issue

                                      -7-
<PAGE>

               shall be treated as an issue of Common Stock covered by the
               provisions of Subsection (1) of Section (f) hereof.

           (j) RESTRICTIVE LEGEND. Each Warrant Share, when issued, shall
               include a legend in substantially the following form: THE
               ISSUANCE OF THESE SHARES HAS NOT BEEN REGISTERED UNDER THE
               SECURITIES ACT OF 1933 (THE "ACT") NOR UNDER ANY STATE SECURITIES
               LAW AND THESE SHARES MAY NOT BE PLEDGED, SOLD, ASSIGNED OR
               OTHERWISE TRANSFERRED UNTIL A (1) REGISTRATION STATEMENT UNDER
               THE ACT AND ANY APPLICABLE STATE SECURITIES LAW HAS BECOME
               EFFECTIVE WITH RESPECT THERETO, OR (2) RECEIPT BY THE COMPANY OF
               AN OPINTION OF COUNSEL ACCEPTABLE TO THE COMPANY (IF SO
               REQUESTED) TO THE EFFECT THAT REGISTRATION UNDER THE ACT OR
               APPLICABLE STATE SECURITIES LAW IS NOT REQUIRED IN CONNECTION
               WITH THE PROPOSED TRANSFER.

           (k) NO IMPAIRMENT. The Company will not, by amendment of its charter
               or through reorganization, consolidation, merger, dissolution,
               sale of assets or any other voluntary action, avoid or seek to
               avoid the observance or performance of any of the terms of this
               Warrant, but will at all times in good faith assist in the
               carrying out of all such terms and in the taking of all such
               action as may be necessary or appropriate in order to protect the
               rights of the holder of this Warrant against impairment.

                            [signature page follows]

                                      -8-
<PAGE>

Dated:  May 1, 2003

                                                  ALLION HEALTHCARE, INC.

                                                  By:
                                                     ---------------------------
                                                        Name:  Michael Moran
                                                        Title:  President & CEO

                       [signature page warrant for Darin]

                                      -9-
<PAGE>

                                  PURCHASE FORM

                                                         Dated_______________ __

           The undersigned hereby irrevocably elects to exercise the within
Warrant to the extent of purchasing ________ shares of Common Stock and hereby
makes payment of _______ in payment of the actual exercise price thereof. In
lieu of payment of the actual exercise price, the undersigned may direct the
Company to net issue such shares of Common Stock in accordance with Section
(a)(2) of the within Warrant by writing "net issue" in the space after "payment"
of in the preceding sentence.

                     INSTRUCTIQNS FOR REGISTRATION OF STOCK

Name
    ----------------------------------------------------------------------------
                               (Please typewrite or print in block letters)

Address
       -------------------------------------------------------------------------

           Signature
                    ------------------------------------------------------------

                                      -10-
<PAGE>

                                 ASSIGNMENT FORM

           FOR VALUE RECEIVED; _____________________ hereby sells, assigns and
transfers unto

Name
    ----------------------------------------------------------------------------
                               (Please typewrite or print in block letters)

Address
       -------------------------------------------------------------------------

the right to purchase Common Stock represented by this Warrant to the extent of
________ shares as to which such right is exercisable and does hereby
irrevocably constitute and appoint ______________ attorney, to transfer the same
on the books of the Company with full power of substitution in the premises.

Date                           ,  200_
    ---------------------------

Signature
         ---------------------------------

                                      -11-
<PAGE>Exhibit 4.2

                                                                  Execution Copy

THE ISSUANCE OF THIS WARRANT AND THE OFFER AND SALE OF THE SHARES OF COMMON
STOCK ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
1933 (THE "ACT") NOR UNDER ANY STATE SECURITIES LAW AND THIS WARRANT AND ANY
SUCH SHARES OF COMMON STOCK MAY NOT BE PLEDGED, SOLD, ASSIGNED OR OTHERWISE
TRANSFERRED UNTIL A (1) REGISTRATION STATEMENT UNDER THE ACT AND ANY APPLICABLE
STATE SECURITIES LAW HAS BECOME EFFECTIVE WITH RESPECT THERETO, OR (2) RECEIPT
BY THE COMPANY OF AN OPINION OF COUNSEL ACCEPTABLE TO THE COMPANY (IF SO
REQUESTED) TO THE EFFECT THAT REGISTRATION UNDER THE ACT OR APPLICABLE STATE
SECURITIES LAW IS NOT REQUIRED IN CONNECTION WITH THE PROPOSED TRANSFER.

           Void after 5:00 p.m. Eastern Standard Time, on May 1, 2008.
           Warrant to Purchase 11,364 Shares of Common Stock.

                        WARRANT TO PURCHASE COMMON STOCK

                                       OF

                             ALLION HEALTHCARE, INC.

           This is to certify that, for good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, Allan H. Peterson
("HOLDER") is entitled to purchase, subject to the provisions of this Warrant,
from Allion Healthcare, Inc., a Delaware corporation ("COMPANY"), ELEVEN
THOUSAND THREE HUNDRED SIXTY FOUR (11,364) fully paid, validly issued and
nonassessable shares of Common Stock, $0.01 par value per share, of the Company
("COMMON STOCK") at a price initially set at eleven Dollars ($11.00) per share
at any time or from time to time during the period from the date hereof to
expiration, but not later than 5:00 p.m. Eastern Standard Time, on May 1, 2008.
The number of shares of Common Stock to be received upon the exercise of this
Warrant and the price to be paid for each share of Common Stock may be adjusted
from time to time as hereinafter set forth. The shares of Common Stock
deliverable upon such exercise, and as adjusted from time to time, are
hereinafter sometimes referred to as "WARRANT SHARES" and the exercise price of
a share of Common Stock in effect at any time and as adjusted from time to time
is hereinafter sometimes referred to as the "EXERCISE PRICE".

           (a) EXERCISE OF WARRANT.

               (1)  This Warrant may be exercised in whole or in part at any
                    time or from time to time on or after the date hereof and
                    until 5:00 p.m Eastern Standard Time on May 1, 2008;
                    provided, however, that if either such day is a day on which
                    banking institutions in the State of New York are

<PAGE>

                    authorized by law to close, then on the next succeeding day
                    which shall not be such a day. This Warrant may be exercised
                    by presentation and surrender hereof to the Company at its
                    principal office, or at the office of its stock transfer
                    agent, if any, with the Purchase Form annexed hereto duly
                    executed and accompanied by payment of the Exercise Price
                    for the number of Warrant Shares specified in such form. As
                    soon as practicable after each such exercise of this
                    Warrant, but not later than seven (7) days from the date of
                    such exercise, the Company shall issue and deliver to the
                    Holder a certificate for the Warrant Shares issuable upon
                    such exercise, registered in the name of the Holder or its
                    designee. If this Warrant should be exercised in part only,
                    the Company shall, upon surrender of this Warrant for
                    cancellation, execute and deliver a new Warrant evidencing
                    the rights of the Holder thereof to purchase the balance of
                    the Warrant Shares purchasable thereunder. Upon receipt by
                    the Company of this Warrant at its office, or by the stock
                    transfer agent of the Company, if any, at its office, in
                    proper form for exercise together with payment in full of
                    the exercise price for the Warrant Shares to be purchased,
                    the Holder shall be deemed to be the holder of record of the
                    shares of Common Stock issuable upon such exercise,
                    notwithstanding that the stock transfer books of the Company
                    shall then be closed or that certificates representing such
                    shares of Common Stock shall not then be physically
                    delivered to the Holder.

               (2)  In lieu of delivering the Exercise Price in cash or check,
                    the Holder may elect to receive shares equal to the value of
                    the Warrant or portion thereof being exercised ("NET ISSUE
                    EXERCISE"). If the Holder wishes to elect the Net Issue
                    Exercise, the Holder shall notify the Company of its
                    election in writing at the time it delivers the Purchase
                    Form to the Company. In the event the Holder shall elect Net
                    Issue Exercise, the Holder shall receive the number of
                    shares of Common Stock equal to the product of (a) the
                    number of shares of Common Stock purchasable under the
                    Warrant, or portion thereof being exercised, and (b) the
                    current market value, as defined in paragraph (c) below, of
                    one share of Common Stock minus the Exercise Price, divided
                    by (c) the current market value, as defined in paragraph (c)
                    below, of one share of Common Stock.

           (b) RESERVATION OF SHARES. The Company shall at all times reserve for
               issuance and/or delivery upon exercise of this Warrant such
               number of shares of its Common Stock as shall be required for
               issuance and delivery upon exercise of this Warrant.

           (c) FRACTIONAL SHARES. No fractional shares or scrip representing
               fractional shares shall be issued upon the exercise of this
               Warrant. With respect to any fraction of a share called for upon
               any exercise hereof, the Company shall pay to the Holder an
               amount in cash equal to such fraction multiplied by the current
               market value of a share, determined as follows:

                                       -2-
<PAGE>

               (1)  If the Common Stock is listed on a national securities
                    exchange or admitted to unlisted trading privileges on such
                    exchange or listed for trading on the NASDAQ system, the
                    current market value shall be the last reported sale price
                    of the Common Stock on such exchange or system on the last
                    business day prior to the date of exercise of this Warrant
                    or if no such sale is made on such day, the mean of the last
                    reported bid and asked prices for such day on such exchange
                    or system; or

               (2)  If the Common Stock is not so listed or admitted to unlisted
                    trading privileges, the current market value shall be the
                    mean of the last reported bid and asked prices reported by
                    the National Quotation Bureau, Inc. on the last business day
                    prior to the date of the exercise of this Warrant; or

               (3)  If the Common Stock is not so listed or admitted to unlisted
                    trading privileges and bid and asked prices are not so
                    reported, the current market value of a share of Common
                    Stock shall be an amount, not less than book value thereof
                    as at the end of the most recent fiscal year of the Company
                    ending prior to the date of the exercise of the Warrant,
                    determined in such reasonable manner as may be prescribed by
                    the Board of Directors of the Company.

           (d) EXCHANGE, TRANSFER, ASSIGNMENT OR LOSS OF WARRANT. Subject to the
               restrictions noted at the beginning of this Warrant, this Warrant
               is exchangeable, without expense, at the option of the Holder,
               upon presentation and surrender hereof to the Company or at the
               office of its stock transfer agent, if any, for other warrants of
               different denominations entitling the holder thereof to purchase
               in the aggregate the same number of shares of Common Stock
               purchasable hereunder. Upon surrender of this Warrant to the
               Company at its principal office or at the office of its stock
               transfer agent, if any, with the Assignment Form annexed hereto
               duly executed and funds sufficient to pay any transfer tax, the
               Company shall, without charge, execute and deliver a new Warrant
               in the name of the assignee named in such instrument of
               assignment and this Warrant shall promptly be cancelled. This
               Warrant may be divided or combined with other warrants which
               carry the same rights upon presentation hereof at the principal
               office of the Company or at the office of its stock transfer
               agent, if any, together with a written notice specifying the
               names and denominations in which new Warrants are to be issued
               and signed by the Holder hereof. The term "WARRANT" as used
               herein includes any Warrants into which this Warrant may be
               divided or exchanged. Upon receipt by the Company of evidence
               satisfactory to it of the loss, theft, destruction or mutilation
               of this Warrant, and (in the case of loss; theft or destruction)
               of reasonably satisfactory indemnification, and upon surrender
               and cancellation of this Warrant, if mutilated, the Company will
               execute and deliver a new Warrant of like tenor and date. Any
               such new Warrant executed and delivered shall constitute an
               additional contractual obligation on the part of the Company,
               whether or not this Warrant so lost, stolen, destroyed, or
               mutilated shall be at any time enforceable by anyone.

                                      -3-
<PAGE>

           (e) RIGHTS OF THE HOLDER. The Holder shall not, by virtue hereof, be
               entitled to any rights of a shareholder in the Company, either at
               law or equity, and the rights of the Holder are limited to those
               expressed in the Warrant and are not enforceable against the
               Company except to the extent set forth herein.

           (f) ANTI-DILUTION AND ADJUSTMENT' PROVISIONS. The Exercise Price in
               effect at any time and the number of securities purchasable upon
               the exercise of the Warrant shall be subject to adjustment from
               time to time upon the happening of certain events as follows:

               (1)  In case the Company shall (i) declare a dividend or make a
                    distribution on its outstanding shares of Common Stock in
                    shares of Common Stock, (ii) subdivide or reclassify its
                    outstanding shares of Common Stock into a greater number of
                    shares, or (iii) combine or reclassify its outstanding
                    shares of Common Stock into a smaller number of shares, the
                    Exercise Price in effect at the time of the record date for
                    such dividend or distribution, or of the effective date of
                    such subdivision, combination or reclassification shall be
                    adjusted so that it shall equal the price determined by
                    multiplying the Exercise Price by a fraction, the
                    denominator of which shall be the number of shares of Common
                    Stock outstanding after giving effect to such action, and
                    the numerator of which shall be the number of shares of
                    Common Stock outstanding immediately prior to such action.
                    Such adjustment shall be made successively whenever any
                    event listed above shall occur.

               (2)  In case the Company shall fix a record date for the issuance
                    of rights or warrants to all holders of its Common Stock
                    entitling them to subscribe for or purchase shares of Common
                    Stock (or securities convertible into Common Stock) at a
                    price (the "SUBSCRIPTION PRICE") (or having a conversion
                    price per share) less than the Exercise Price on such record
                    date, the Exercise Price shall be adjusted so that the same
                    shall equal the price determined by multiplying the Exercise
                    Price in effect immediately prior to the date of issuance by
                    a fraction, the numerator of which shall be the sum of the
                    number of shares outstanding on the record date mentioned
                    above and the number of additional shares of Common Stock
                    which the aggregate offering price of the total number of
                    shares of Common Stock so offered (or the aggregate
                    conversion price of the convertible securities so offered)
                    would purchase at the Exercise Price in effect immediately
                    prior to the date of such issuance, and the denominator of
                    which shall be the sum of the number of shares of Common
                    Stock outstanding on the record date mentioned above and the
                    number of additional shares of Common Stock offered for
                    subscription or purchase (or into which the convertible
                    securities so offered are convertible). Such adjustment
                    shall be made successively whenever such rights or warrants
                    are issued and shall become effective immediately after the
                    record date for the determination of shareholders entitled
                    to receive such rights or warrants; and to the extent that
                    shares of Common Stock are not delivered (or

                                      -4-
<PAGE>

                    securities convertible into Common Stock are not delivered)
                    after the expiration of such rights or warrants, the
                    Exercise Price shall be readjusted to the Exercise Price
                    which would then be in effect had the adjustments made upon
                    the issuance of such rights or warrants been made upon the
                    basis of delivery of only the number of shares of Common
                    Stock (or securities convertible into Common Stock) actually
                    delivered.

               (3)  In case the Company shall hereafter distribute to the
                    holders of its Common Stock evidences of its indebtedness or
                    assets (excluding cash dividends or distributions and
                    dividends or distributions referred to in Subsection (1)
                    above) or subscription rights or warrants (excluding those
                    referred to in Subsection (2) above), then in each such case
                    the Exercise Price in effect thereafter shall be determined
                    by multiplying the Exercise Price in effect immediately
                    prior thereto by a fraction, the numerator of which shall be
                    the total number of shares of Common Stock outstanding
                    multiplied by the current market price per share of Common
                    Stock (as defined in Section (c) above), less the fair
                    market value (as determined by the Company's Board of
                    Directors) of said assets or evidences of indebtedness so
                    distributed or of such rights or warrants, and the
                    denominator of which shall be the total number of shares of
                    Common Stock outstanding multiplied by such current market
                    price per share of Common Stock. Such adjustment shall be
                    made successively whenever such a record date is fixed. Such
                    adjustment shall be made whenever any such distribution is
                    made and shall become effective immediately after the record
                    date for the determination of shareholders entitled to
                    receive such distribution.

               (4)  Whenever the Exercise Price payable upon exercise of each
                    Warrant is adjusted pursuant to Subsections (1), (2), and
                    (3) above, the number of Shares purchasable upon exercise of
                    this Warrant shall simultaneously be adjusted by multiplying
                    the number of Shares initially issuable upon exercise of
                    this Warrant by the Exercise Price in effect on the date
                    hereof and dividing the product so obtained by the Exercise
                    Price, as adjusted.

               (5)  In the case of the issuance of securities convertible into
                    or exchangeable for shares of Common Stock, the aggregate
                    consideration received therefor shall be deemed to be the
                    consideration received by the Company for the issuance of
                    such securities plus the additional minimum consideration,
                    if any, to be received by the Company upon the conversion or
                    exchange thereof the consideration in each case to be
                    determined in the same manner as provided in clauses (A) and
                    (B) of this Subsection (5).

               (6)  No adjustment in the Exercise Price shall be required unless
                    such adjustment would require an increase or decrease of at
                    least five cents ($0.05) in such price; provided, however,
                    that any adjustments which by reason of this Subsection (6)
                    are not required to

                                      -5-
<PAGE>

                    be made shall be carried forward and taken into account in
                    any subsequent adjustment required to be made hereunder. All
                    calculations under this Section (f) shall be made to the
                    nearest cent or to the nearest one-hundredth of a share, as
                    the case may be. Anything in this Section (f) to the
                    contrary notwithstanding, the Company shall be entitled, but
                    shall not be required, to make such changes in the Exercise
                    Price, in addition to those required by this Section (f), as
                    it shall determine, in its sole discretion, to be advisable
                    in order that any dividend or distribution in shares of
                    Common Stock, or any subdivision, reclassification or
                    combination of Common Stock, hereafter made by the Company
                    shall not result in any federal income tax liability to the
                    holders of Common Stock or securities convertible into
                    Common Stock (including Warrants).

               (7)  The Company may retain a firm of independent certified
                    public accountants selected by the Board of Directors (who
                    may be the regular accountants employed by the Company) to
                    make any computation required by this Section (f), and a
                    certificate signed by such firm shall be conclusive evidence
                    of the correctness of such adjustment.

               (8)  In the event that at any time, as a result of an adjustment
                    made pursuant to Subsection (1) above, the Holder of this
                    Warrant thereafter shall become entitled to receive any
                    shares of the Company, other than Common Stock, thereafter
                    the number of such other shares so receivable upon exercise
                    of this Warrant shall be subject to adjustment from time to
                    time in a manner and on terms as nearly equivalent as
                    practicable to the provisions with respect to the Common
                    Stock contained in Subsections (1) to (6) inclusive above.

               (9)  Irrespective of any adjustments in the Exercise Price or the
                    number or kind of shares purchasable upon exercise of this
                    Warrant, Warrants theretofore or thereafter issued may
                    continue to express the same price and number and kind of
                    shares as are stated in the similar Warrants initially
                    issuable pursuant to this Agreement.

           (g) OFFICER'S CERTIFICATE. Whenever the Exercise Price shall be
               adjusted as required by the provisions of Section (f), the
               Company shall promptly and in no event later than 20 days after
               the effective date of adjustment cause to be mailed by certified
               mail to each Holder at his last address appearing in the Warrant
               Register and shall forthwith file, in the custody of its
               Secretary or an assistant Secretary at its principal office and
               with its stock transfer agent, if any, an officer's certificate
               showing the adjusted Exercise Price determined as herein
               provided, setting forth in reasonable detail the facts requiring
               such adjustment, including a statement of the number of
               additional shares of Common Stock, if any, and such other facts
               as shall be necessary to show the reason for and the manner of
               computing such adjustment. Each such officer's certificate shall
               be made available at all reasonable times for inspection by the
               Holder or any holder of a Warrant executed and delivered pursuant
               to Section (a).

                                      -6-
<PAGE>

           (h) NOTICES TO WARRANT HOLDERS. So long as this Warrant shall be
               outstanding, (i) if the Company shall pay any dividend or make
               any distribution upon the Common Stock or (ii) if the Company
               shall offer to the holders of Common Stock for subscription or
               purchase by them any share of any class or any other rights or
               (iii) if any capital reorganization of the Company,
               reclassification of the capital stock of the Company,
               consolidation or merger of the Company with or into another
               corporation, sale, lease or transfer of all or substantially all
               of the property and assets of the Company to another corporation,
               or voluntary or involuntary dissolution, liquidation or winding
               up of the Company shall be effected, then in any such case, the
               Company shall cause to be mailed by certified mail to the Holder,
               at least fifteen days prior to the date specified in (x) or (y)
               below, as the case may be, a notice containing a brief
               description of the proposed action and stating the date on which
               (x) a record is to be taken for the purpose of such dividend,
               distribution or rights, or (y) such reclassification,
               reorganization, consolidation, merger, conveyance, lease,
               dissolution, liquidation or winding up is to take place and the
               date, if any is to be fixed, as of which the holders of Common
               Stock or other securities shall receive cash or other property
               deliverable upon such reclassification, reorganization,
               consolidation, merger, conveyance, dissolution, liquidation or
               winding up.

           (i) RECLASSIFICATION REORGANIZATION OR MERGER. In case of any
               reclassification, capital reorganization or other change of
               outstanding shares of Common Stock of the Company, or in case of
               any consolidation or merger of the Company with or into another
               corporation (other than a merger with a subsidiary in which
               merger the Company is the continuing corporation and which does
               not result in any reclassification, capital reorganization or
               other change or outstanding shares of Common Stock of the class
               issuable upon exercise of this Warrant) or in case of any sale,
               lease or conveyance to another corporation of the property of the
               Company as an entirety, the Company shall, as a condition
               precedent to such transaction, cause effective provisions to be
               made so that the Holder shall have the right thereafter by
               exercising this Warrant at any time prior to the expiration of
               the Warrant, to purchase the kind and amount of shares of stock
               and other securities and property receivable upon such
               reclassification, capital reorganization and other change,
               consolidation, merger, sale or conveyance by a holder of the
               number of shares of Common Stock which might have been purchased
               upon exercise of this Warrant immediately prior to such
               reclassification, change, consolidation, merger, sale or
               conveyance. Any such provision shall include provision for
               adjustments which shall be as nearly equivalent as may be
               practicable to the adjustments provided for in this Warrant. The
               foregoing provisions of this Section (i) shall similarly apply to
               successive reclassifications, capital reorganizations and changes
               of shares of Common Stock and to successive consolidations,
               mergers, sales or conveyances. In the event that in connection
               with any such capital reorganization or reclassification,
               consolidation, merger, sale or conveyance, additional shares of
               Common Stock shall be issued in exchange, conversion,
               substitution or payment, in whole or in part, for a security of
               the Company other than Common Stock, any such issue

                                      -7-
<PAGE>

               shall be treated as an issue of Common Stock covered by the
               provisions of Subsection (1) of Section (f) hereof.

           (j) RESTRICTIVE LEGEND. Each Warrant Share, when issued, shall
               include a legend in substantially the following form: THE
               ISSUANCE OF THESE SHARES HAS NOT BEEN REGISTERED UNDER THE
               SECURITIES ACT OF 1933 (THE "ACT") NOR UNDER ANY STATE SECURITIES
               LAW AND THESE SHARES MAY NOT BE PLEDGED, SOLD, ASSIGNED OR
               OTHERWISE TRANSFERRED UNTIL A (1) REGISTRATION STATEMENT UNDER
               THE ACT AND ANY APPLICABLE STATE SECURITIES LAW HAS BECOME
               EFFECTIVE WITH RESPECT THERETO, OR (2) RECEIPT BY THE COMPANY OF
               AN OPINTION OF COUNSEL ACCEPTABLE TO THE COMPANY (IF SO
               REQUESTED) TO THE EFFECT THAT REGISTRATION UNDER THE ACT OR
               APPLICABLE STATE SECURITIES LAW IS NOT REQUIRED IN CONNECTION
               WITH THE PROPOSED TRANSFER.

           (k) NO IMPAIRMENT. The Company will not, by amendment of its charter
               or through reorganization, consolidation, merger, dissolution,
               sale of assets or any other voluntary action, avoid or seek to
               avoid the observance or performance of any of the terms of this
               Warrant, but will at all times in good faith assist in the
               carrying out of all such terms and in the taking of all such
               action as may be necessary or appropriate in order to protect the
               rights of the holder of this Warrant against impairment.

                            [signature page follows]

                                      -8-
<PAGE>

Dated:  May 1, 2003

                                       ALLION HEALTHCARE, INC.

                                       By:
                                          --------------------------------------
                                             Name:  Michael Moran
                                             Title:  President & CEO

                       [signature page warrant for Allan]

                                      -9-
<PAGE>

                                  PURCHASE FORM

                                                            Dated_______________

           The undersigned hereby irrevocably elects to exercise the within
Warrant to the extent of purchasing ________ shares of Common Stock and hereby
makes payment of _______ in payment of the actual exercise price thereof. In
lieu of payment of the actual exercise price, the undersigned may direct the
Company to net issue such shares of Common Stock in accordance with Section
(a)(2) of the within Warrant by writing "net issue" in the space after "payment"
of in the preceding sentence.

                     INSTRUCTIQNS FOR REGISTRATION OF STOCK

Name
    ----------------------------------------------------------------------------
                               (Please typewrite or print in block letters)

Address
       -------------------------------------------------------------------------

           Signature
                    ------------------------------------------------------------

                                      -10-
<PAGE>

                                 ASSIGNMENT FORM

           FOR VALUE RECEIVED; _____________________ hereby sells, assigns and
transfers unto

Name
    ----------------------------------------------------------------------------
                               (Please typewrite or print in block letters)

Address
       -------------------------------------------------------------------------

the right to purchase Common Stock represented by this Warrant to the extent of
________ shares as to which such right is exercisable and does hereby
irrevocably constitute and appoint ______________ attorney, to transfer the same
on the books of the Company with full power of substitution in the premises.

Date                           ,  200_
    ---------------------------

Signature
         ---------------------------------

                                      -11-
<PAGE>

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