<PAGE>
                                                                    EXHIBIT 10.1


                        COMMON STOCK PURCHASE AGREEMENT


                                BY AND BETWEEN


                             AETHER SYSTEMS, INC.


                                      AND


                           DATA CRITICAL CORPORATION


                           Dated as of June 2, 2000
<PAGE>

                        COMMON STOCK PURCHASE AGREEMENT
                        -------------------------------


          This COMMON STOCK PURCHASE AGREEMENT, dated as of June 2, 2000 (this
"Agreement"), is entered into by and between Aether Systems, Inc., a Delaware
----------
corporation (the "Purchaser"), and Data Critical Corporation, a Delaware
                  ---------
corporation (the "Company").
                  -------

                                   RECITALS

          A.  Purchaser desires to purchase, and the Company desires to issue
and sell, shares of common stock, $0.001 par value per share, of the Company
(the "Common Stock"), upon the terms and subject to the conditions set forth in
      ------------
this Agreement.

          B.  As provided herein, it is contemplated that Purchaser and the
Company will enter into an option agreement at the Closing, pursuant to which
the Company will grant to the Purchaser an option to purchase Option Shares
(certain defined terms used herein shall have the meaning given to them in
Section 7.12).

          NOW, THEREFORE, in consideration of the foregoing and of the
covenants, agreements, representations and warranties hereinafter contained, the
Purchaser and the Company hereby agree as follows:

                                   ARTICLE I

                ISSUANCE AND SALE OF COMMON STOCK; THE CLOSING
                ----------------------------------------------

          1.1 Issuance and Sale of Common Stock.  Upon the terms and subject to
              ---------------------------------
the conditions set forth in this Agreement, the Purchaser agrees to purchase
1,230,770 shares of Common Stock (the "Shares"), which represents the quotient
                                       ------
of $10 million (the "Purchase Price") divided by the per Share closing price of
                     --------------
the Company's Common Stock immediately prior to the execution of this Agreement.
The per Share closing price is the last reported sale price of the Common Stock
during regular trading hours on the date hereof if this Agreement shall be
executed subsequent to the close of trading on the Nasdaq National Market System
("Nasdaq") on the date hereof, or, if this Agreement shall be executed prior to
  ------
the opening of trading on Nasdaq on the date hereof or if such date is not a
trading day, the last reported sale price of the Common Stock during regular
trading hours on the Nasdaq National Market System on the last trading day
immediately preceding the execution of this Agreement.

          1.2 The Closing.  Subject to the satisfaction or waiver of the
              -----------
conditions set forth in Article IV, unless the parties otherwise agree, the
closing of the sale and purchase of the Shares (the "Closing") shall occur at
                                                     -------
the offices of Jones, Day, Reavis & Pogue, 901 Lakeside Avenue, Cleveland, Ohio
44114, at 8:00 a.m., Eastern daylight time, on June 5, 2000, or at such other
time or on such other date as the parties may agree to in writing.  The "Closing
                                                                         -------
Date" shall be the date the Closing occurs.
----

          1.3 Transactions at and after the Closing.  At the Closing, subject
              -------------------------------------
to the terms and conditions of this Agreement:
<PAGE>

          (a)  the Company shall deliver to the Purchaser, free and clear of any
Lien (as defined herein), a certificate registered in the Purchaser's name and
representing the Shares;

          (b)  the Purchaser will pay to the Company, by wire transfer of
immediately available funds to an account specified by the Company, the Purchase
Price; and

          (c)  the Purchaser and the Company shall execute and deliver:

               (i)    the Registration Rights Agreement in the form set forth in

     Exhibit A hereto (the "Registration Rights Agreement");
     ---------              -----------------------------

               (ii)   the Option Agreement in the form set forth in Exhibit B
                                                                   ---------
     hereto (the "Option Agreement");
                  ----------------

               (iii)  the AIM License substantially in the form set forth in

     Exhibit C hereto (the "AIM License");
     ---------              -----------

               (iv)  the Amendment No. 1 to Confidentiality Agreement
     substantially in the form set forth in Exhibit D hereto, (the "Amendment,"
                                            ---------               ---------
     and together with the Confidentiality Agreement, dated as of May 1, 2000 by
     and between the Purchaser and the Company, the "Confidentiality
                                                     ---------------
     Agreement");

               (v)   the Omnibus Consent and Amendment to Registration Rights
     Agreement substantially in the form set forth in Exhibit E hereto (the
                                                      ---------
     "Consent"); provided that the Purchaser shall have no obligation to execute
     --------    --------
     and deliver the Consent unless the Company and Demand Holders (as defined
     in the Consent) holding at least two-thirds of the outstanding shares of
     Restricted Stock (as defined in the Consent) have executed and delivered
     the Consent; and

               (vi)  the Marketing and Technology Development Agreement
     substantially in the form set forth in Exhibit F hereto (the "Development
                                            ---------              -----------
     Agreement" and, together with the Registration Rights Agreement, the Option
     ---------
     Agreement, the AIM License, the Confidentiality Agreement, and the Consent,
     the "Other Transaction Documents").
          ---------------------------

                                  ARTICLE II

                         REPRESENTATION AND WARRANTIES
                         -----------------------------

          2.1  Representations and Warranties of Purchaser.  The Purchaser
               -------------------------------------------
represents and warrants to the Company, as of the date hereof and as of the
Closing Date, and, with respect to Section 2.1.4, Section 2.1.5, Section 216,
Section 217, Section 2.1.8 and Section 2.1.9, as of the date of any exercise and
closing under the Option Agreement (unless another date or period of time is
specifically stated herein for a representation or warranty), as follows:

               2.1.1 Corporate Organization.  The Purchaser is a corporation
                     ----------------------
duly organized, validly existing and in good standing under the laws of the
State of Delaware. The Purchaser has

                                       2
<PAGE>

all requisite corporate power and authority to enter into this Agreement and the
Other Transaction Documents.

          2.1.2  Authorization and Validity of Agreements.   The Purchaser has
                 ----------------------------------------
all requisite corporate power and authority to enter into this Agreement and the
Other Transaction Documents and perform its obligations hereunder and
thereunder.  The execution, delivery and performance by the Purchaser of this
Agreement, the Other Transaction Documents and any other certificates, documents
and instruments contemplated hereby or thereby or referred to herein or therein,
and the consummation by it of the transactions contemplated hereby and thereby
have been, or as of the Closing Date will have been, duly authorized by all
necessary corporate action of the Purchaser.  The purchase of the Shares as
contemplated herein has been approved by the Board of Directors of the
Purchaser.  This Agreement has been duly executed and delivered by the Purchaser
and, assuming the due authorization, execution and delivery hereof by the
Company, is a legal, valid and binding obligation of the Purchaser, enforceable
against it in accordance with its terms, except as limited by (i) bankruptcy,
                                                               -
insolvency, reorganization, moratorium, fraudulent conveyance, or other similar
laws now or hereafter in effect relating to creditors' rights generally and (ii)
                                                                             --
general principles of equity.

          2.1.3  No Conflicts.  The execution, delivery and performance by the
                 ------------
Purchaser of this Agreement and the Other Transaction Documents, and the
consummation by the Purchaser of the transactions contemplated hereby and
thereby, will not:

          (a)    conflict with, violate or result in a breach or violation of
the certificate of incorporation or bylaws of the Purchaser;

          (b)    result in a violation or breach of, or constitute (with or
without due notice or lapse of time or both) a default or give rise to any right
to termination, cancellation, or acceleration under, or result in the creation
or imposition of any charge, claim, judgment, lease, liability, mortgage, lien,
pledge, restriction, preemptive right, security interest, tax lien, or
encumbrance (each, a "Lien") on or against any of the assets or properties of
                      ----
the Purchaser pursuant to any of the terms or conditions of any note, bond,
mortgage, indenture, license, agreement or other instrument or obligation (the

"Contracts") to which the Purchaser is a party or by which the Purchaser or any
----------
of its properties or assets may be bound, except as has not had or would not
have a Material Adverse Effect, or require any third party consent, waiver or
approval in order that any Contracts remain in effect without material
modification after the Closing Date, except for such consent, waiver or approval
as has not had or would not have a Material Adverse Effect;

          (c)    violate any statute, law, rule, regulation, writ, injunction,
decree, or order (including any award, decision, judgment, injunction, ruling,
subpoena, or verdict entered, issued, made or tendered by any Governmental
Authority ("Applicable Law") binding on or affecting the Purchaser or any of its
            --------------
assets or properties, except for such violation as has not had and would not
have a Material Adverse Effect.

          2.1.4  Purchase Entirely for Own Account.  The Shares or the Option
                 ---------------------------------
Shares, as the case may be, to be acquired by the Purchaser will be acquired for
investment for the Purchaser's own account (or for accounts over which it
exercises investment authority), not as a

                                       3
<PAGE>

nominee or agent, and not with a view to or for sale or distribution of any part
thereof in violation of any securities laws, and the Purchaser has no present
intention of selling, granting any participation in, or otherwise distributing
the same. The Purchaser does not presently have any contract, undertaking,
agreement or arrangement with any Person to sell, transfer or grant
participations to such Person or to any third Person, with respect to any of the
Shares or the Option Shares. The Purchaser has not been formed for the specific
purpose of acquiring the Shares or the Option Shares.

          2.1.5  Government Approvals.  Except for applicable filings, if any,
                 --------------------
required by applicable federal and state securities laws, in each case, which
shall be made (or are not required to be made) on or prior to the Closing Date,
no consent, authorization or order of, or filing or registration with, any
Governmental Authority (a "Governmental Approval") or other Person is required
                           ---------------------
to be obtained or made by the Purchaser for the execution, delivery and
performance of this Agreement or the Other Transaction Documents, except where
the failure to obtain such consents, authorizations or orders, or make such
filings or registrations, would not reasonably be expected to prevent or impair
the ability of the Company to consummate the transactions contemplated hereby or
thereby.

          2.1.6  Company Information.  The Purchaser represents and warrants
                 -------------------
that (i) it has received the Company's forms, reports and other documents filed
      -
by the Company (the "SEC Filings") since November 8, 1999 under the Securities
                     -----------
Exchange Act of 1934, as amended (including the rules and regulations
thereunder, the "Exchange Act") or the Securities Act of 1933, as amended
                 ------------
(including the rules and regulations thereunder, the "Securities Act"), and has
                                                      --------------
reviewed the SEC Filings and all of the other materials furnished to it in
connection with the transactions contemplated hereby, (ii) it has been granted
                                                       --
the opportunity to ask questions of, and receive answers from, representatives
of the Company concerning the terms and conditions of the purchase of the Shares
and the Option Shares and to obtain any additional information that it deems
necessary to verify the accuracy of the information contained in such materials
and (iii) it has received all such other information as the Purchaser considered
     ---
necessary or desirable to make an informed decision to invest in the Shares.

          2.1.7  Restricted Securities.  The Purchaser understands that the
                 ---------------------
Shares and the Option Shares have not been registered under the Securities Act,
by reason of a specific exemption from the registration provisions of the
Securities Act which depends upon, among other things, the bona fide nature of
the investment intent and the accuracy of the Purchaser's representations as
expressed herein.  The Purchaser understands that the Shares and the Option
Shares, when issued or granted, as applicable, are "restricted securities" under
applicable U.S. federal and state securities laws and that, pursuant to these
laws, the Purchaser must hold such Shares indefinitely unless they are
registered with the Securities and Exchange Commission (the "SEC") and qualified
                                                             ---
by state authorities, or an exemption from such registration and qualification
requirements is available.  The Purchaser acknowledges that the Company has no
obligation to register or qualify the Shares or the Option Shares for resale
except as set forth in the Registration Rights Agreement.  The Purchaser further
acknowledges that if an exemption from registration or qualification is
available, it may be conditioned on various requirements including, but not
limited to, the time and manner of sale, the holding period for the Shares or
Option Shares, and on requirements relating to the Company which are outside of
the

                                       4
<PAGE>

Purchaser's control, and which (except as provided in the Registration Rights
Agreement) the Company is under no obligation and may not be able to satisfy.

          2.1.8 Legends.  The Purchaser understands that the certificates
                ------
representing the Shares and the Option Shares, when issued or granted, as
applicable, may bear one or all of the following legends:

          (a)    "THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
                 REGISTERED PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT
                 UNDER THE SECURITIES ACT OF 1933, AS AMENDED, AND MAY NOT BE
                 TRANSFERRED, SOLD, PLEDGED, HYPOTHECATED OR OTHERWISE DISPOSED
                 OF UNLESS (i) (A) SUCH DISPOSITION IS PURSUANT TO AN EFFECTIVE
                 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933, AS
                 AMENDED, (B) SUCH DISPOSITION IS EXEMPT FROM THE PROVISIONS OF
                 SECTION 5 OF SUCH ACT OR (C) A NO-ACTION LETTER FROM THE
                 SECURITIES AND EXCHANGE COMMISSION, REASONABLY SATISFACTORY TO
                 COUNSEL FOR THE COMPANY, SHALL HAVE BEEN OBTAINED WITH RESPECT
                 TO SUCH DISPOSITION AND (ii) SUCH DISPOSITION IS PURSUANT TO
                 REGISTRATION UNDER ANY APPLICABLE STATE SECURITIES LAWS OR AN
                 EXEMPTION THEREFROM."

          (b)    Any legend required by the securities or "blue sky" laws of any
state to the extent such laws are applicable to the Shares and the Option
Shares, when issued, represented by the certificate so legended.

          2.1.9  Accredited Investor.  The Purchaser is (i) an "accredited
                 -------------------                     -
investor" as defined in Rule 501(a) under the Securities Act or (ii) is a
                                                                 --
sophisticated investor, experienced in investing in securities of emerging
growth companies and acknowledges that the Purchaser is able to fend for itself,
can bear the economic risk of its investment and has such knowledge and
experience in financial and business matters that it is capable of evaluating
(either alone or together with its representatives) the merits and risks of the
investment in the Shares and, if exercised, the Option Shares.

          2.1.10 Brokers.  No broker, finder, agent or similar intermediary has
                 -------
acted on behalf of the Purchaser in connection with this Agreement or the
transactions contemplated hereby, and there are no brokerage commissions,
finder's fees or similar fees or commissions payable by the Purchaser in
connection with this Agreement or the transactions contemplated hereby.

          2.1.11 HSR Act Filings.  To the Purchaser's knowledge, no filings are
                 ---------------
required by the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended
(the "HSR Act") in connection with the Closing under this Agreement.

                                       5
<PAGE>

          2.1.12 Litigation.  There is no claim, action, suit, proceeding or
                 ----------
investigation, including, without limitation, those of any federal agency,
pending or, to the Purchaser's knowledge, threatened against or affecting the
Purchaser, its properties, assets or business, that questions the validity of
this Agreement or the Other Transaction Documents or the right of the Purchaser
to enter into this Agreement or the Other Transaction Documents, or to
consummate the transactions contemplated hereby or thereby, or that could
reasonably be expected to alter or delay the transactions contemplated hereby or
thereby.

     2.2  Representations and Warranties of the Company.  The Company represents
          ---------------------------------------------
and warrants to the Purchaser, as of the date hereof and as of the Closing Date
(unless another date or period of time is specifically stated herein for a
representation or warranty), as follows:

          2.2.1  Corporate Organization.  The Company and its subsidiaries are
                 ----------------------
corporations duly organized, validly existing and in good standing under the
laws of their respective jurisdiction of incorporation.  Each of the Company and
its subsidiaries has all requisite corporate power and authority to own or lease
and operate its properties and to carry on its business as it is currently being
conducted.  Each of the Company and its subsidiaries is licensed or qualified to
do business as a foreign corporation and is in good standing in each
jurisdiction in which the properties owned, leased or operated by it or the
nature of its respective business makes such qualification or licensing
necessary, except for such jurisdictions in which the failure to be so qualified
or licensed has not had and would not have a Material Adverse Effect.  The
Company has delivered to the Purchaser or its agents complete and correct copies
of the certificates of incorporation and bylaws of each of the Company and its
subsidiaries as in effect on the date hereof.

          2.2.2  Authorization and Validity of Agreements.  The Company has all
                 ----------------------------------------
requisite corporate power and authority to enter into this Agreement and the
Other Transaction Documents and perform its obligations hereunder and
thereunder.  The execution, delivery and performance by the Company of this
Agreement, the Other Transaction Documents and any other certificates, documents
and instruments contemplated hereby or thereby or referred to herein or therein,
and the consummation by it of the transactions contemplated hereby and thereby
have been, or as of the Closing Date will have been, duly authorized by all
necessary corporate action of the Company.  The sale of the Shares and the grant
of the Option Shares as contemplated herein and in the Option Agreement has been
approved by the Board of Directors of the Company (the "Board of Directors").
                                                        ------------------
This Agreement has been duly executed and delivered by the Company and, assuming
the due authorization, execution, and delivery hereof by the Purchaser, is a
legal, valid and binding obligation of the Company, enforceable against it in
accordance with its terms, except as limited by (i) bankruptcy, insolvency,
                                                 -
reorganization, moratorium, fraudulent conveyance, or other similar laws now or
hereafter in effect relating to creditors' rights generally and (ii) general
                                                                 --
principles of equity.

          2.2.3  No Conflicts.  Except as set forth on Schedule 2.2.3, the
                 ------------                          --------------
execution, delivery and performance by the Company of this Agreement and the
Other Transaction Documents, and the consummation by the Company of the
transactions contemplated hereby and thereby, will not:

                                       6
<PAGE>

               (a)  conflict with, violate or result in a breach or violation of
the certificate of incorporation or bylaws of the Company;

               (b)  result in a violation or breach of, or constitute (with or
without due notice or lapse of time or both) a default or give rise to any right
to termination, cancellation, or acceleration under, or result in the creation
or imposition of any Lien on or against any of the assets or properties of the
Company pursuant to any of the terms or conditions of any Contracts to which the
Company is a party or by which the Company or any of its properties or assets
may be bound, except as has not had or would not have a Material Adverse Effect,
or require any third party consent, waiver or approval in order that any
Contracts remain in effect without material modification after the Closing Date,
except for such consent, waiver or approval as has not had or would not have a
Material Adverse Effect; or

               (c)  violate any Applicable Law binding on or affecting the
Company or any of its assets or properties, except for such violation as has not
had or would not have a Material Adverse Effect.

     2.2.4     Capital Stock of the Company.  The authorized capital stock of
               ----------------------------
the Company consists solely of 25,000,000 shares of Common Stock and 3,000,000
shares of preferred stock ("Preferred Stock").  As of June 1, 2000, 10,970,465
shares of Common Stock were issued and outstanding and no shares of Preferred
Stock were issued and outstanding.  All of the issued and outstanding shares of
capital stock of the Company have been duly authorized, validly issued and are
fully paid and nonassessable.  Except as set forth in Schedule 2.2.4, there are
                                                      --------------
(i) no preemptive or similar rights on the part of any holders of any class of
 -
securities of the Company or its subsidiaries, (ii) no outstanding
                                                --
subscriptions, options, warrants or other rights, agreements, commitments,
arrangements or understandings of any kind (contingent or otherwise) obligating
the Company to issue or sell, or cause to be issued or sold any shares of
capital stock of any class of the Company (or any securities convertible into or
exchangeable or exercisable for any such shares of capital stock), and no
authorization has been given in respect thereof, (iii) no restrictions upon, or
                                                  ---
agreements or understandings of the Company or any subsidiary, or understandings
of any other Person, with respect to, the voting or transfer of any shares of
capital stock of the Company or any subsidiary and (iv) no outstanding
                                                    --
contractual obligations of the Company or any of its subsidiaries to repurchase,
redeem or otherwise acquire any shares of capital stock of the Company or any of
its subsidiaries.  The Company is the sole beneficial owner of all the issued
and outstanding capital stock of its subsidiaries.  Immediately following the
Closing, the issued and outstanding capital stock of the Company will be as set
forth in Schedule 2.2.4
         --------------

     2.2.5     Financial Statements and Reports.  Since November 9, 1999, the
               --------------------------------
Company has filed all filings required to be filed by it under the Securities
Act or the Exchange Act.  The SEC Filings were prepared and filed in accordance
with the rules and regulations of the SEC.  As of their respective dates, except
to the extent that information contained in any SEC Filing has been revised or
superseded by a later filed SEC Filing, the SEC Filings did not contain any
untrue statement of a material fact or omit to state a material fact required to
be stated therein or necessary to make the statements made therein, in light of
the circumstances under which they were made, not misleading.  The financial
statements of the Company (including any related notes or schedules) included in
the SEC Filings were prepared in accordance with generally

                                       7
<PAGE>

accepted accounting principles ("GAAP") applied on a consistent basis (except as
                                 ----
otherwise noted in such financial statements) and present fairly in all material
respects the consolidated financial condition, results of operations and cash
flows of the Company as of the dates thereof and for the periods indicated,
subject, in the case of interim financial statements, to normal year end audit
adjustments. Except (i) as set forth in the SEC Filings, (ii) as set forth on
                     -                                    --
Schedule 2.2.5 or (iii) as incurred after the date of the most recently filed
--------------
Quarterly Report on Form 10-Q filed by the Company, in the ordinary course of
business of the Company consistent with prior practice and not prohibited by
this Agreement, the Company has not, as of the date hereof, incurred any
liabilities or obligations of any nature whatsoever (whether accrued, absolute,
contingent, or otherwise and whether due or to become due) in excess of
$100,000.

          2.2.6  Litigation.  Schedule 2.2.6 sets forth each claim, action,
                 ----------   --------------
suit, proceeding or investigation pending or, to the Company's knowledge,
threatened against the Company or any of its subsidiaries and each outstanding
order, writ, injunction or decree to or by which the Company or any of its
subsidiaries is subject or any of their assets or properties is bound.  There is
no claim, action, suit, proceeding or investigation, including, without
limitation, those of any federal agency, pending or, to the Company's knowledge,
threatened against or affecting the Company, its properties, assets or business,
that questions the validity of this Agreement or the Other Transaction Documents
or the right of the Company to enter into this Agreement or the Other
Transaction Documents, or to consummate the transactions contemplated hereby or
thereby, or that could reasonably be expected to alter or delay the transactions
contemplated hereby or thereby.

          2.2.7  Government Approvals.  Except for immaterial Governmental
                 --------------------
Approvals, all Governmental Approvals necessary for the conduct of the Company's
business and operations have been duly obtained and are in full force and
effect.  There are no proceedings pending or, to the knowledge of the Company,
threatened that would result in the revocation, cancellation or suspension, or
any adverse modification, of any such Governmental Approval.  Except for (i)
                                                                          -
applicable filings, if any, required by applicable federal and state securities
laws, which shall be made (or are not required to be made) on or prior to the
Closing Date and (ii) as set forth on Schedule 2.2.7, no Governmental Approval
                  --                  --------------
or consent, authorization or order of, or filing or registration with any other
Person is required to be obtained or made by the Company for the execution,
delivery and performance of this Agreement or the Other Transaction Documents,
except where the failure to obtain such consents, authorizations or orders, or
make such filings or registrations, would not reasonably be expected to prevent
or impair the ability of the Company to consummate the transactions contemplated
hereby or thereby.

          2.2.8  Compliance with Laws.  Neither the Company nor any of its
                 --------------------
subsidiaries or any affiliated Person of such Person is in violation of or
default under (i) any Applicable Law applicable to it or any of its properties
               -
or business, (ii) any provision of its certificate of incorporation, bylaws or
              --
other organizational documents, or (iii) any Contract, except for any such
                                    ---
violations of and defaults under any such Applicable Law or Contract that,
individually and in the aggregate, have not had and would not have a Material
Adverse Effect.  Without limiting the foregoing, each of the Company and its
subsidiaries has been in compliance with, and neither the Company nor any of its
subsidiaries has received notice of any violation of or default under, all laws,
regulations, ordinances and rules (including those of any non-governmental self-
regulatory agencies) applicable to it or its operations that has not been cured
or waived, except

                                       8
<PAGE>

for such non-compliance, notice or default as has not had or would not have a
Material Adverse Effect.

          2.2.9  Validity of Securities.  At the Closing, the Shares to be
                 ----------------------
issued to the Purchaser will be duly authorized, and upon payment therefor by
the Purchaser, validly issued, fully paid and nonassessable, and the Purchaser
will acquire good and valid title to the Shares, free and clear of all Liens.
At any closing under the Option Agreement, the Option Shares issued to the
holder thereunder will be duly authorized, and upon payment therefor by such
holder, validly issued, fully paid and nonassessable, and such holder will
acquire good and valid title to the Option Shares, free and clear of all Liens.
Assuming the accuracy of the representations and warranties of the Purchaser set
forth in Section 214, Section 2.1.6, Section 2.1.7, Section 2.1.8 and Section
2.1.9, the issuance and sale of the Shares pursuant to this Agreement and the
Option Shares pursuant to the Option Agreement will be exempt from registration
under the Securities Act and will not otherwise violate Applicable Law.

          2.2.10 Absence of Material Adverse Effect.  Since the date of the most
                 ----------------------------------
recent financial statements contained in the SEC Filings, there has not been a
Material Adverse Effect.

          2.2.11 Disclosure.  No representation or warranty by the Company
                 ----------
contained in this Agreement, and no statement contained in any document,
certificate or schedule delivered by or on behalf of the Company pursuant to
this Agreement or in connection with the consummation of the transactions
contemplated hereby, including the Other Transaction Documents, contains or will
contain any untrue statement of a material fact, or omits or, when executed and
delivered, will omit to state any material fact necessary, in light of the
circumstances under which it is or will be made, in order to make the statements
herein or therein not misleading.

          2.2.12 Permit and Licenses.  The Company and its subsidiaries have
                 -------------------
obtained all  permits, licenses, franchises and authorizations required by
Governmental Authorities for the Company and its subsidiaries to own their
respective assets and properties and conduct their respective businesses as
currently conducted, except for those of which the failure to obtain would not
have a Material Adverse Effect with respect to the Company or its ability to
perform under this Agreement or the Other Transaction Documents.

          2.2.13 Intellectual Property, etc.  The Company owns, or will own,
                 --------------------------
or is or will be licensed or otherwise has or will have, as applicable, the
right to use all software, inventions, patents, patent applications, trademarks,
mask works, service marks and copyrights ("Intellectual Property") used in or
                                           ---------------------
necessary for the Company's business, as presently conducted at the time of the
Closing, and as proposed to be conducted under the Development Agreement, except
for such Intellectual Property as may be (a) developed jointly pursuant to the
Development Agreement or (b) owned or licensed by the Purchaser and used in or
necessary for the Company's business.  The Company's ownership and/or use of
Intellectual Property in its business, as presently conducted, does not conflict
with, or result in any violation of, or default (with or without notice or lapse
of time or both) under, or give rise to a right of termination, cancellation or
acceleration of any obligation or result in any loss of a material benefit under
or the creation of any Lien in or upon any of the properties or assets of the
Company under, any contract between the Company and any Person or, to the
Company's knowledge, any other

                                       9
<PAGE>

intellectual property rights of any other Person, except for any such conflict,
violation, default, right of termination, cancellation, acceleration, loss of
material benefit or creation of any Lien which would not have a Material Adverse
Effect with respect to the Company. Except as set forth on Schedule 2.2.13, the
                                                           ---------------
Company has not received any communications alleging that the Company has
violated or, by conducting its business, would, to the Company's knowledge,
infringe upon the intellectual property rights of any other Person. Except as
set forth on Schedule 2.2.13, the Company is not aware of any potential
             ---------------
infringements or misappropriation by others of any of its Intellectual Property.

          2.2.14 Brokers.  No broker, finder, agent or similar intermediary has
                 -------
acted on behalf of the Company in connection with this Agreement or the
transactions contemplated hereby, and there are no brokerage commissions,
finder's fees or similar fees or commissions payable by the Company in
connection with this Agreement or the transactions contemplated hereby.

          2.2.15 HSR Act Filings.  To the Company's knowledge, no filings are
                 ---------------
required by the HSR Act in connection with the Closing under this Agreement.


                                  ARTICLE III

                                   COVENANTS
                                   ---------

     3.1  Listing of Additional Shares.  The Company will file with the Nasdaq
          ----------------------------
National Market a Notification Form for Listing of Additional Shares for
an amount of shares of Common  Stock equal to at least the amount of the Shares
and the amount of Shares subject to the Option Agreement.

     3.2  Operation of Business.  From the date hereof until the Closing Date,
          ---------------------
 except as set forth in Schedule 3.2, the Company shall, and shall cause
                        ------------
each of its subsidiaries to;

          (a) operate its business in all material respects in the ordinary
course and in compliance with Applicable Laws applicable to it or any of its
assets or properties;

          (b) except as contemplated by Section 3.4, not adopt any amendment to
its certificate of incorporation or bylaws;

          (c) not split, combine or reclassify any shares of the Company's
capital stock;

          (d) not declare or pay any dividend or distribution (whether in cash,
stock or property) in respect of its capital stock or increase the number of
shares subject to the Company's 1999 Stock Option Plan or 1999 Director's Stock
Option Plan;

          (e) not make any payment or distribution on account of, or set apart
assets for a sinking or analogous fund for, the purchase, redemption,
defeasance, retirement or other acquisition of, any shares of the Company's
capital stock or warrants to acquire shares of the Company's capital stock,
whether now or hereafter outstanding, or make any other distribution in respect
thereof;

                                      10
<PAGE>

          (f) not take any action, or knowingly omit to take any action, that
would, or that would reasonably be expected to, result in (i) any of the
                                                           -
representations and warranties of the Company set forth in Article II becoming
untrue or (ii) any of the conditions or the obligations set forth in Section 4.1
           --
and Section 4.3 not being satisfied; and

          (g) enter into any agreement or commitment to do any of the foregoing
subsections (a) through (f).

     3.3  Access to Books and Records.  The Company shall afford to the
          ---------------------------
Purchaser and the Purchaser's accountants, counsel and representatives full
access during normal business hours throughout the period prior to the Closing
Date (or the earlier termination of this Agreement pursuant to Section 6.1) to
all its properties, books, contracts, commitments and records (including, but
not limited to, tax returns) and, during such period, shall, upon request,
furnish promptly to the Purchaser (i) a copy of each report, schedule and other
                                   -
document filed or received by any of them pursuant to the requirements of
federal or state securities laws and (ii) all other information concerning its
                                      --
business, properties and personnel as the Purchaser may reasonably request,
provided, however, that the Company shall have no obligation to afford to the
--------  -------
Purchaser or the Purchaser's accountants, counsel or representatives access to
any material, non-public information in violation of any securities law, and
provided, further, that no investigation or receipt of information pursuant to
--------  -------
this Section 3.3 shall affect any representation or warranty of the Company or
the conditions to the obligations of the Purchaser.

     3.4  Agreement to Take Necessary and Desirable Actions.  The Company and
          -------------------------------------------------
Purchaser shall (i) subject to the satisfaction of the conditions set forth in
                 -
Section 4.1, Section 4.2 and Section 4.3, execute and deliver the Other
Transaction Documents and such other documents, certificates, agreements and
other writings and (ii) take such other actions, in each case, as may be
                    --
necessary or reasonably requested by the other party in order to consummate or
implement the transactions contemplated by this Agreement and the Other
Transaction Documents, including, but not limited to, in the case of the
Company, (x) amending its certificate of incorporation and bylaws, if necessary,
to accommodate the issuance and delivery of the Shares in accordance with the
terms of this Agreement and the Option Shares in accordance with the terms of
the Option Agreement and (y) causing Demand Holders holding at least two-thirds
of the outstanding shares of Restricted Stock to execute and deliver the
Consent.

     3.5  Compliance with Conditions; Reasonable Best Efforts.  Each of the
          ---------------------------------------------------
Company and the Purchaser shall use its best efforts to cause all conditions
precedent to its own obligations to be satisfied.  Upon the terms and subject to
the conditions of this Agreement, the Company and Purchaser will use reasonable
best efforts to take, or cause to be taken, all actions, and to do, or cause to
be done, all things necessary, proper or advisable consistent with Applicable
Law to consummate the transactions contemplated herein except that, except to
the extent provided in Section 7.2, the Company shall not be obligated to pay
any monies, to incur any obligations or to transfer or dispose of any properties
or rights to effect the transactions contemplated hereby.

     3.6  Legends.  After the requirement for the restrictive legend described
          -------
in Section 2.1.8 hereof is no longer applicable because the Shares or the Option
Shares are freely transferable under the Securities Act, the Company shall
remove such legend upon request from the holder of such Shares, if such holder
delivers evidence reasonably satisfactory to counsel for

                                      11
<PAGE>

the Company, which evidence may include an opinion of counsel, to the effect
that the transfer of such Shares is no longer restricted by the Securities Act.

     3.7  Compliance with Laws.  The Company shall, and shall cause its
          --------------------
subsidiaries to, comply in all material respects with all Applicable Law
applicable to it or any of its assets or properties, including all state
securities or "blue sky" laws, applicable to the sale of the Shares to the
Purchaser.

     3.8  Purchaser Representative.  Within five business days following the
          ------------------------
date of the Closing (as defined) under the Option Agreement, the Purchaser
shall recommend to the Secretary of the Company or the Company's nominating
committee, if any, a nominee to the Board of Directors.  Promptly thereafter,
the Company shall notify the Purchaser whether the nominee is acceptable to a
majority of the members of the Board of Directors, such acceptance not to be
unreasonably withheld.  If the nominee is not accepted, the Company shall
provide the Purchaser with a reasonable period of time to recommend a new
nominee, which nominee shall also be subject to the acceptance by a majority of
the Board of Directors, such acceptance not to be unreasonably withheld or
delayed.  The Company agrees to cause the accepted nominee to be appointed as a
member of the Board of Directors at the next regularly scheduled meeting of the
Board of Directors.  The Company covenants and agrees that the number of
directors constituting the Board of Directors shall not be increased to a number
equal to or greater than 12 without obtaining the Purchaser's prior written
consent to such increase.

     3.9  Public Announcements.  Each party shall have the right to review,
          ---------------------
comment upon and approve any publicity materials, press releases or other public
statements by the other party that name or otherwise identify such party or any
of its affiliates or refer to, or describe any aspect of, this Agreement or the
Other Transaction Documents or the transactions contemplated hereby and thereby;
provided, however, that with respect to disclosure documents to be filed by
--------  -------
either party under the Exchange Act or the Securities Act, subject to the last
sentence of this Section 3.9, each party shall only have the right to prior
review and to comment upon the other party's documents.  Each party agrees that
it will not issue any such publicity materials, press releases or public
statements without the prior written approval of the other party, which approval
shall not be unreasonably withheld, conditioned or delayed.  The Company and the
Purchaser shall cooperate with each other to request confidential treatment as
may be mutually agreed by them with respect to certain terms of this Agreement,
the Other Transaction Documents and the transactions contemplated hereby and
thereby in any filing with the SEC, any other Governmental Authority or any
securities exchange or over-the-counter market.

     3.10 Lock-Up.  To the extent not inconsistent with applicable law,
          -------
the Purchaser hereby agrees that, during the period commencing on the date of
the Closing and ending one year from the date of the Closing, the Purchaser
shall not, without the consent of the Company sell or otherwise transfer or
dispose of any Shares, including any additional shares of Common Stock owned by
the Purchaser as a result of stock splits or dividends.

                                      12
<PAGE>

                                  ARTICLE IV

                             CONDITIONS PRECEDENT
                             --------------------

     4.1  Conditions Precedent to Obligations of Parties.  The respective
          ----------------------------------------------
obligations of the Purchaser, on the one hand, and the Company, on the other, to
consummate the transactions contemplated by this Agreement are subject to the
satisfaction or waiver, at or prior to the Closing Date, of each of the
following conditions:

          4.1.1  No Injunction, Etc.  There shall be no outstanding order,
                 ------------------
injunction, decree or judgment or statute, rule, regulation or administrative or
executive order which restrains, enjoins, prohibits or declares illegal, or
imposes or would impose damages in connection with, the consummation of the
transactions contemplated by this Agreement and the Other Transaction Documents,
and there shall be no action, suit or proceeding pending or threatened seeking
any of the foregoing.

          4.1.2  Registration Rights Agreement.  The Company and the Purchaser
                 -----------------------------
shall have executed and delivered a Registration Rights Agreement.

          4.1.3  Option Agreement.  The Company and the Purchaser shall have
                 ----------------
executed and delivered an Option Agreement.

          4.1.4  AIM License.  The Company and the Purchaser shall have executed
                 -----------
and delivered an AIM License.

          4.1.5  Confidentiality Agreement.  The Company and the Purchaser shall
                 -------------------------
have executed and delivered an Amendment.

          4.1.6  Development Agreement.  The Company and the Purchaser shall
                 ---------------------
have executed and delivered a Development Agreement.

     4.2  Conditions Precedent to Obligations of the Company.  In addition to
          --------------------------------------------------
the conditions set forth in Section 4.1, the obligations of the Company to
consummate the transactions to be consummated at the Closing are subject to the
satisfaction or waiver, at or prior to the Closing Date, of each of the
additional conditions set forth below:

          4.2.1  Delivery of Purchase Price.  The Purchaser shall have paid to
                 --------------------------
the Company, by wire transfer of immediately available funds to an account
specified by the Company, the Purchase Price.

          4.2.2  Accuracy of Representations and Warranties.  The
                 ------------------------------------------
representations and warranties of the Purchaser contained in this Agreement (i)
                                                                             -
shall have been true and correct when made and (ii) other than any
                                                --
representation or warranty made as of a specific date shall be (x) in the case
                                                                -
of representations and warranties that are qualified as to materiality, true and
correct in all respects and (y) in all other cases, true and correct in all
                             -
material respects, in the case of the clauses (x) and (y), as of the Closing
Date with the same force and effect as though made on and as of the Closing
Date.

                                      13
<PAGE>

          4.2.3  Performance of Agreements.  Purchaser shall have performed in
                 -------------------------
all material respects all obligations and agreements, and complied in all
material respects with all covenants and conditions contained in this Agreement,
to be performed or complied with by it prior to or at the Closing Date.

          4.2.4  Certificates.  The Company shall have received a certificate
                 ------------
from the Purchaser, dated the Closing Date, signed by an authorized signatory of
Purchaser, in his capacity as an officer of Purchaser, to the effect that, to
his knowledge, the conditions specified in Section 422 and Section 4.2.3 have
been satisfied.

     4.3  Conditions Precedent to the Obligations of Purchaser.  In addition
          ----------------------------------------------------
to the conditions set forth in Section 4.1, the obligations of Purchaser to
consummate the transactions to be consummated at the Closing are subject to the
satisfaction or waiver, at or prior to the Closing Date, of each of the
additional conditions set forth below:

          4.3.1  Accuracy of Representations and Warranties.  The
                 ------------------------------------------
representations and warranties of the Company contained in this Agreement (i)
                                                                           -
shall have been true and correct when made and (ii) other than any
                                                --
representation or warranty made as of a specific date, shall be (x) in the case
                                                                 -
of representations and warranties that are qualified as to materiality, true and
correct and (y) in all other cases, true and correct in all material respects,
             -
in the case of the clauses (x) and (y), as of the Closing Date with the same
force and effect as though made on and as of the Closing Date.

          4.3.2  Performance of Agreements.  The Company shall have performed in
                 -------------------------
all material respects all obligations and agreements, and complied in all
material respects with all covenants and conditions contained in this Agreement,
to be performed or complied with by it prior to or at the Closing Date.

          4.3.3  Certificates.  Purchaser shall have received a certificate from
                 ------------
the Company, dated the Closing Date, signed by the President or any authorized
Vice President of the Company, in his capacity as an officer of the Company, to
the effect that, to his knowledge, the conditions specified in Section 4.3.1 and
Section 4.3.2 have been satisfied.

          4.3.4  Opinion of Counsel for the Company.  Purchaser shall have
                 ----------------------------------
received an opinion of the Company's counsel dated the Closing Date in
substantially the form set forth in Exhibit G hereto.
                                    ---------

          4.3.5  Consent.  The Company shall have delivered a Consent executed
                 -------
by the Company and Demand Holders holding at least two-thirds of the outstanding
shares of Restricted Stock.

          4.3.6  Other Deliveries.  The Company shall have delivered to
                 ----------------
Purchaser at the Closing the following:

          (a)    a certificate registered in the Purchaser's name representing
the Shares;

          (b)    a certificate of incumbency for the officers executing the
documents on behalf of the Company;

                                      14
<PAGE>

          (c) a certified copy of the resolutions duly adopted by the directors
of the Company and signed by the Secretary or Assistant Secretary authorizing
the transactions contemplated by this Agreement;

          (d) a certificate of the Secretary or Assistant Secretary certifying
that the resolutions referred to in Section 4.3.6(c) have not been rescinded,
modified or withdrawn and that such resolutions are in full force and effect as
of the Closing Date; and

          (e) such further certificates and documents evidencing the
consummation by the Company of the transactions contemplated hereby as Purchaser
shall reasonably request.

     4.4  Waiver of Conditions.  Each of the parties, in its discretion, may
          --------------------
waive, in whole or in part, at or prior to the Closing Date, the failure of
satisfaction of any of the conditions precedent to its obligations set forth
herein.  No such waiver by either of the parties shall be effective unless made
in writing.

                                   ARTICLE V

                                INDEMNIFICATION
                                ---------------

     5.1  Survival of Representations, Etc.  All statements contained in any
          --------------------------------
schedule or in any certificate delivered by or on behalf of the Company pursuant
to this Agreement or in connection with the transactions contemplated hereby
shall be deemed to be representations and warranties by the Company hereunder.
The representations and warranties of each of the Company and the Purchaser
shall survive the Closing Date for a period of one year from the Closing Date.
Each covenant and agreement contained in this Agreement shall survive in
accordance with the specific terms thereof.

     5.2  Indemnification by Company.  Subject to Section 5.3, the Company shall
          --------------------------
indemnify the Purchaser and its affiliates and their respective officers,
directors, employees, financial advisors, attorneys, accountants, agents and
affiliates (collectively, the "Indemnified Parties") against, and hold each
                               -------------------
Indemnified Party harmless from, any damage, claim, loss, cost, liability or
expense, including interest, penalties, reasonable attorneys' fees and the
Indemnified Party's expenses of investigation, response action or remedial
action (collectively, "Damages"), incident to, arising out of, in connection
                       -------
with or related to, whether directly or indirectly, any of the following:

          (a) the breach of any representation or warranty of the Company that
is identified by the Purchaser prior to termination of the representation and
warranty survival period set forth in Section 5.1; or

          (b) any breach by the Company of any of its covenants or agreements
set forth in this Agreement,

except to the extent (but only to the extent) any such Damages are incident to,
arise out of, in connection with or are related to, whether directly or
indirectly, the gross negligence or willful misconduct of the Indemnified
Parties.  The Company's responsibility to indemnify the

                                      15
<PAGE>

Indemnified Parties in accordance with the provisions of this Section 5.2 shall
not preclude the Company from asserting any claim against the Purchaser for a
breach of the Purchaser's representations, warranties, covenants or agreements
under this Agreement or any Other Transaction Document to the extent the
Company's Damages relate to such breach of the Purchaser.

          5.3  Limitations on Liability.  The total amount of the Company's
               ------------------------
indemnification liability to the Indemnified Parties under Section 5.2 for all
breaches of the Company's representations, warranties, covenants and agreements
contained in this Agreement shall in each case be limited to an amount equal to
the sum of (i) the Purchase Price plus (ii) the reasonable attorneys' fees and
            -                           --
other expenses of the prevailing party.

          5.4  Claims for Indemnification.  Whenever any claim shall arise for
               --------------------------
indemnification under Article V, the Indemnified Parties shall promptly notify
the Company of the claim and, when known, the facts constituting the basis for
such claim.  In the event of any claim for indemnification hereunder resulting
from or in connection with any claim or legal proceedings by a third party, the
notice to the Company shall specify, if known, the amount of the liability
arising therefrom.  The Indemnified Parties shall not settle or compromise any
claim by a third party for which it is entitled to indemnification hereunder
without the prior written consent of the Company.  The Company shall not settle
any claim by a third party for which an Indemnified Party is entitled to
indemnification hereunder without obtaining a full and unconditional release
against the Indemnified Party.

          5.5  Defense by Indemnifying Party.  In connection with any claim
               -----------------------------
giving rise to a right of indemnification under Article V resulting from or
arising out of any claim or legal proceeding by a Person who is not a party to
this Agreement, the Company, at its sole cost and expense may, upon written
notice to an Indemnified Party, assume the defense of any such claim or legal
proceeding, provided that (i) the counsel for the Company who shall conduct the
            --------       -
defense of such claim or legal proceeding shall be reasonably satisfactory to
the Indemnified Party, (ii) the Indemnified Party shall be entitled to
                        --
participate in (but not control) the defense of any such action, with its
counsel and at its own expense and (iii) the omission by any Indemnified Party
                                    ---
to give notice as provided herein of any claim as to which indemnity may be
sought shall not relieve the Company of its indemnification obligations under
this Agreement except to the extent such omission to give notice materially
prejudices the Company; provided, further, that, if (x) the Indemnified Party
                        --------  -------            -
reasonably concludes that a conflict of interest exists with respect to the
interests of any Indemnified Party and the Company or (y) if the Indemnified
                                                       -
Party may have available to it one or more defenses or counterclaims that are
inconsistent with one or more of those that may be available to the Company in
respect of any claim or legal proceeding relating thereto, the Indemnified Party
shall have the right at all times to retain its own counsel and take over and
assume control over the defense, settlement or litigation of, and negotiations
relating to its own defense or the legal proceeding as it relates to the
Purchaser at the sole expense of the Company.  It is understood that the Company
shall not, in connection with any claim or legal proceeding in the same
jurisdiction, be liable for the reasonable fees and expenses of more than one
separate firm of attorneys at any time for all such Indemnified Parties.  If the
Company does not timely assume the defense of any such claim or legal proceeding
resulting therefrom, (a) an Indemnified Party may defend against such claim or
                      -
legal proceeding, in such manner as it may deem appropriate, including, but not
limited to, settling such claim or legal proceeding with the

                                      16
<PAGE>

written consent of the Company (not to be unreasonably withheld or delayed), and
(b) the Company shall be entitled to participate in (but not control) the
 -
defense of such action, with its counsel and at its own expense.

                                  ARTICLE VI

                            TERMINATION AND DEFAULT
                            -----------------------

     6.1  General.  This Agreement may be terminated and the transactions
          -------
contemplated hereby may be abandoned at any time prior to the Closing Date, as
set forth below:

          6.1.1  Mutual Consent.  This Agreement may be terminated by the mutual
                 --------------
written consent of the parties.

          6.1.2  Order or Decree.  This Agreement may be terminated by the
                 ---------------
Purchaser or the Company if any Governmental Authority shall have issued an
order, decree, ruling or taken any other action restraining, enjoining or
otherwise prohibiting in any material respects the transactions contemplated
hereby and such order, decree, ruling or other action shall have become final
and nonappealable.  If any filing is required in connection with this Agreement
under the HSR Act, a delay caused by a request for additional information in
connection with such filing shall not constitute a basis upon which to terminate
this Agreement pursuant to this Section 612.

          6.1.3  Outside Date.  This Agreement may be terminated by either party
                 ------------
(a) if the Closing shall not have occurred by June 30, 2000 (the "Outside Date")
                                                                  ------------
or (b) if one or more conditions to the other party's obligation to consummate
the transactions contemplated hereby cannot be satisfied by the Outside Date;
provided, however, that no party may exercise its rights under this Section
--------  -------
6.1.3 if such party is in material breach or default under this Agreement.

          6.1.4  No Material Adverse Effect.  This Agreement may be terminated
                 --------------------------
by the Purchaser if a Material Adverse Effect with respect to the Company shall
have occurred.

          6.1.5  Breach.  This Agreement may be terminated by either party if
                 ------
the other party shall have breached any of its material representations or
warranties or obligations under this Agreement and shall have failed to cure
such breach within ten (10) days after notice of such breach from the other
party.

     6.2  Procedure Upon Termination.  In the event of the termination of this
          --------------------------
Agreement, written notice thereof shall promptly be given to the other party
hereto and this Agreement shall terminate, all further obligations of the
parties hereunder to satisfy the conditions precedent to the Closing shall
terminate, and the transactions contemplated hereby shall be abandoned without
further action by any of the parties hereto.

     6.3  Effect of Termination.  Nothing in this Article VI shall relieve any
          ---------------------
party hereto of any liability for intentional or willful breach of this
Agreement, including willful failure to fulfill a condition or to perform a
covenant. The parties shall have no liability for termination of this Agreement
for any reason other than an intentional or willful breach of this Agreement.

                                      17
<PAGE>

                                  ARTICLE VII

                                 MISCELLANEOUS
                                 -------------

          7.1  Notices.  Except as otherwise provided, all notices which are
               -------
permitted or required under this Agreement shall be in writing and shall be
deemed given (i) when delivered personally, (ii) if by fax upon transmission
              -                              --
with confirmation of receipt by the receiving party's facsimile terminal, (iii)
                                                                           ---
if sent by documented overnight delivery service on the date delivered or (iv)
                                                                           --
if sent by mail, five (5) business days after being mailed by registered or
certified mail, return receipt postage prepaid, addressed as follows, or to such
other Person or address as may be designated by notice to the other party:

          If to the Company, to:

          Data Critical Corporation
          19820 North Creek Parkway, Suite 100
          Bothell, Washington  98011
          Attn:  Michael E. Singer
          Phone:  (425) 482-7025
          Facsimile:  (425) 482-7010
          with a copy (which shall not constitute notice) to:

          Orrick, Herrington & Sutcliffe LLP
          701 Fifth Avenue, Suite 6500
          Seattle, Washington  98104
          Attn:  Scott J. Moore
          Phone:  (206) 839-4300
          Facsimile: (206) 839-4301

          If to the Purchaser, to:

          Aether Systems, Inc.
          11460 Cronridge Drive
          Owings Mills, Maryland  21117
          Attn:  Brian W. Keane
          Phone:  (410) 654-6400
          Facsimile: (410) 654-6554

          with a copy (which shall not constitute notice) to:

          Jones, Day, Reavis & Pogue
          901 Lakeside Ave.
          Cleveland, Ohio  44114
          Attn: Christopher M. Kelly
          Phone: (216) 586-3939
          Facsimile: (216) 579-0212

                                      18
<PAGE>

          7.2  Fees and Expenses.  All expenses incurred in connection with the
               -----------------
negotiation, preparation, execution and performance of this Agreement shall be
paid by the party incurring such expenses; provided, however, that (i) if this
                                           --------  -------        -
Agreement is terminated by the Purchaser for any reason other than Purchaser's
breach of this Agreement, then (without limiting the Purchaser's right to
recover damages pursuant to Section 6.3) the Company shall reimburse the
Purchaser for the Purchaser's reasonable out of pocket expenses incurred in
connection with this Agreement and (ii) the parties will share equally the
                                    --
filing fees related to any filing required under the HSR Act.

          7.3  Assignment.  This Agreement will be binding upon the parties
               ----------
hereto and will inure to the benefit of the parties hereto and their legal
successors and permitted assigns.  This Agreement and the transactions
contemplated hereby may not be assigned or otherwise transferred, in whole or in
part, by operation of law or otherwise, without the prior written consent of the
other party.  Any assignment in violation of this Section will be void and of no
effect.

          7.4  Counterparts.  This Agreement may be executed in two or more
               ------------
counterparts, each of which when so executed and delivered, shall be an original
instrument, but such counterparts together shall constitute a single agreement.

          7.5  Entire Agreement.  This Agreement, including all Exhibits and
               ----------------
Schedules hereto, and all certificates and documents executed and delivered in
connection with this Agreement, including any Other Transaction Document, when
executed and delivered, shall constitute the entire agreement of the parties,
superseding and extinguishing all prior agreements and understandings, and
negotiations between the parties relating to the subject matter hereof.

          7.6  Governing Law.  THIS AGREEMENT AND THE RIGHTS AND OBLIGATIONS OF
               -------------
THE PARTIES HEREUNDER SHALL BE GOVERNED BY THE SUBSTANTIVE LAWS OF THE STATE OF
NEW YORK APPLICABLE TO CONTRACTS MADE AND TO BE PERFORMED THEREIN, WITHOUT
GIVING EFFECT TO THE CONFLICTS OF LAWS RULES THEREOF.

          7.7  Headings.  The headings contained in this Agreement are for
               --------
reference purposes only and shall not affect the meaning or interpretation of
this Agreement.

          7.8  Severability.  Any provision of this Agreement which is invalid
               ------------
or unenforceable shall be ineffective to the extent of such invalidity or
unenforceability, provided that such invalidity or unenforceability does not
deny any party the material benefits of the transactions for which it has
bargained, such invalidity or unenforceability shall not affect in any way the
remaining provisions hereof.

          7.9  Modification and Amendment.  This Agreement may not be modified
               --------------------------
or amended except by written agreement specifically referring to this Agreement
and signed by the parties hereto.

                                      19
<PAGE>

     7.10  Waiver.  No waiver of a breach or default hereunder shall be
           ------
considered valid unless in writing and signed by the party giving such waiver,
and no such waiver shall be deemed a waiver of any subsequent breach or default
of the same or similar nature.

     7.11  Actions.  Each party will execute and deliver to the other, from
           -------
time to time at or after the Closing, for no additional consideration and at no
additional cost to the requesting party, (without incurring any obligation to
pay any money or incur any obligations or transfer or dispose of any properties
or rights) such further assignments, certificates, instruments, records or other
documents, assurances or things as may be reasonably necessary to give full
effect to this Agreement and to allow each party fully to enjoy and exercise the
rights accorded and acquired by it under this Agreement.

     7.12  Terms.  Terms used with initial capital letters will have the
           -----
meanings specified, applicable to both singular and plural forms, for all
purposes of this Agreement.  The words "include" and "exclude" and derivatives
of those words are used in this Agreement in an illustrative sense rather than
limiting sense.

           (a) "Governmental Authority" means any nation or government, any
                ----------------------
state or other political subdivision thereof, any entity exercising executive,
legislative, judicial, regulatory or administrative functions of or pertaining
to government, including, without limitation, any government authority, agency,
department, board, commission or instrumentality of the United Stated, any State
of the United States or any political subdivision thereof, and any tribunal or
arbitrator(s) of competent jurisdiction, and any self-regulatory organization.

           (b) "Material Adverse Effect" means any event, occurrence, fact,
                -----------------------
condition, change or effect that is materially adverse to the business,
operations, results of operations, condition (financial or otherwise), assets
(including intangible assets) or liabilities of the Company and its
subsidiaries, taken as a whole, except (i) for such event, occurrence, fact,
                                        -
condition, change or effect that affects the digital wireless or health care
industries as a whole and (ii) that a change in the trading price of the
                           --
Company's Common Stock alone shall not constitute a Material Adverse Effect.

           (c) "Option Shares" means the shares of Common Stock to be issued by
                -------------
the Company and purchased by the Purchaser in accordance with the terms of the
Option Agreement.

           (d) "Person" means any natural person, firm, partnership,
                ------
association, corporation, company, trust, business trust, Governmental Authority
or other entity.


                          [Execution Page Following]

                                      20
<PAGE>

          IN WITNESS WHEREOF, the parties have caused this Agreement to be
executed by their respective duly authorized representatives, officers or agents
on the date first written above.


                                        AETHER SYSTEMS, INC.


                                        By: /s/ Brian W. Keane
                                            ------------------
                                            Name:  Brian W. Keane
                                            Title: SVP


                                        DATA CRITICAL CORPORATION


                                        By: /s/ Jeffrey S. Brown
                                            --------------------
                                            Name:   Jeffrey S. Brown
                                            Title:  President/CEO