VARIAN MEDICAL SYSTEMS, INC. 2010 EMPLOYEE STOCK PURCHASE PLAN SECTION 1 PURPOSE

Exhibit 10.1

VARIAN MEDICAL SYSTEMS, INC.

2010 EMPLOYEE STOCK PURCHASE PLAN

SECTION 1

PURPOSE

Varian Medical Systems, Inc., a Delaware corporation has established the Varian Medical Systems, Inc. 2010 Employee Stock Purchase Plan in order to provide eligible employees of the Company and its participating Subsidiaries with the opportunity to purchase Common Stock through payroll deductions. The Plan is intended to qualify as an employee stock purchase plan under Section 423(b) of the Code. This plan shall be effective on the later of the date it is adopted by the Board and the date the plan is approved by the Company’s stockholders (the “Effective Date”).

SECTION 2

DEFINITIONS

2.1 “1934 Act” means the Securities Exchange Act of 1934, as amended. Reference to a specific Section of the 1934 Act or regulation thereunder shall include such Section or regulation, any valid regulation promulgated under such Section, and any comparable provision of any future legislation or regulation amending, supplementing or superseding such Section or regulation.

2.2 “Board” means the Board of Directors of the Company.

2.3 “Code” means the Internal Revenue Code of 1986, as amended. Reference to a specific Section of the Code or regulation thereunder shall include such Section or regulation, any valid regulation promulgated under such Section, and any comparable provision of any future legislation or regulation amending, supplementing or superseding such Section or regulation.

2.4 “Committee” shall mean the committee appointed by the Board to administer the Plan. Any member of the Committee may resign at any time by notice in writing mailed or delivered to the Secretary of the Company. As of the Effective Date, the Plan shall be administered by the Compensation and Management Development Committee of the Board.

2.5 “Common Stock” means the common stock of the Company.

2.6 “Company” means Varian Medical Systems, Inc., a Delaware corporation.

2.7 “Compensation” means a Participant’s regular wages. The Committee, in its discretion, may (on a uniform and nondiscriminatory basis) establish a different definition of Compensation prior to an Enrollment Date for all options to be granted on such Enrollment Date.

2.8 “Eligible Employee” means every Employee of an Employer, except (a) any Employee who immediately after the grant of an option under the Plan, would own stock and/or hold outstanding options to purchase stock possessing five percent (5%) or more of the total combined voting power or value of all classes of stock of the Company or of any Subsidiary of the Company (including stock attributed to such Employee pursuant to Section 424(d) of the Code), (b) any Employee not scheduled to work at least five months every calendar year or at least 20 hours per week or (c) as provided in the following sentence. Subject to requirements of Section 423 of the Code, the Committee, in its discretion, from time to time may, prior to an Enrollment Date for all options to be granted on such Enrollment Date, determine (on a uniform and nondiscriminatory basis) that an Employee or class of Employees shall not be an Eligible Employee.

2.9 “Employee” means an individual who is a common-law employee of any Employer, whether such employee is so employed at the time the Plan is adopted or becomes so employed subsequent to the adoption of the Plan.

2.10 “Employer” or “Employers” means any one or all of the Company, and those Subsidiaries which, with the consent of the Board, have adopted the Plan.

2.11 “Enrollment Date” means such dates as may be determined by the Committee (in its discretion and on a uniform and nondiscriminatory basis) from time to time.

2.12 “Grant Date” means any date on which a Participant is granted an option under the Plan.

2.13 “Participant” means an Eligible Employee who (a) has become a Participant in the Plan pursuant to Section 4.1 and (b) has not ceased to be a Participant pursuant to Section 8 or Section 9.

2.14 “Plan” means the Varian Medical Systems, Inc. Employee Stock Purchase Plan, as set forth in this instrument and as hereafter amended from time to time.

2.15 “Purchase Date” means such dates as may be determined by the Committee (in its discretion and on a uniform and nondiscriminatory basis) from time to time prior to an Enrollment Date for all options to be granted on such Enrollment Date.

2.16 “Subsidiary” means any corporation in an unbroken chain of corporations beginning with the Company if each of the corporations other than the last corporation in the unbroken chain then owns stock possessing fifty percent (50%) or more of the total combined voting power of all classes of stock in one of the other corporations in such chain.

SECTION 3

SHARES SUBJECT TO THE PLAN

3.1 Number Available. The number of shares of Common Stock subject to the Plan shall be seven (7) million, which shall include such number of shares of Common Stock remaining available for issuance under the Varian Medical Systems, Inc. Employee Stock Purchase Plan immediately prior to the Effective Date. Shares sold under the Plan may be newly issued shares or treasury shares.

3.2 Adjustments. In the event of any reorganization, recapitalization, stock split, reverse stock split, stock dividend, combination of shares, merger, consolidation, offering of rights or other similar change in the capital structure of the Company, the Board shall make appropriate adjustments in the number, kind and purchase price of the shares available for purchase under the Plan, in the maximum number of shares subject to any option under the Plan and in the maximum number of shares purchasable on any one Purchase Date for any offering period.

SECTION 4

ENROLLMENT

4.1 Participation. Each Eligible Employee may elect to become a Participant by enrolling or re-enrolling in the Plan effective as of any Enrollment Date. In order to enroll, an Eligible Employee must complete and submit to the Company an enrollment form in such form, manner and by such deadline as may be specified by the Committee from time to time (in its discretion and on a nondiscriminatory basis). Any Participant whose option expires and who has not withdrawn from the Plan automatically will be re-enrolled in the Plan on the Enrollment Date immediately following the Purchase Date on which his or her option expires.

4.2 Payroll Withholding. On his or her enrollment form, each Participant must elect to make Plan contributions via payroll withholding from his or her Compensation pursuant to such procedures as the Committee may specify from time to time. A Participant may elect to have withholding equal to a whole percentage from 1% to 10% (or such lesser, or greater, percentage that the Committee may establish from time to time for all options to be granted on any Enrollment Date) of his or her Compensation. A Participant may elect to increase or decrease his or her rate of payroll withholding by submitting a new enrollment form in accordance with such procedures as may be established by the Committee from time to time. A Participant may stop his or her payroll withholding by submitting a new enrollment form in accordance with such procedures as may be established by the Committee from time to time. In order to be effective as of a specific date, an enrollment form must be received by the Company no later than the deadline specified by the Committee, in its discretion and on a nondiscriminatory basis, from time to time. Any Participant who is automatically re-enrolled in the Plan will be deemed to have elected to continue his or her contributions at the percentage last elected by the Participant.

SECTION 5

OPTIONS TO PURCHASE COMMON STOCK

5.1 Grant of Option. On each Enrollment Date on which the Participant enrolls or re-enrolls in the Plan, he or she shall be granted an option to purchase shares of Common Stock.

5.2 Duration of Option. Each option granted under the Plan shall expire upon the conclusion of the option’s offering period which will end on the earliest to occur of (a) the completion of the purchase of shares on the last Purchase Date occurring within 27 months of the Grant Date of such option, (b) such shorter option period as may be established by the Committee from time to time prior to an Enrollment Date for all options to be granted on such Enrollment Date, or (c) the date on which the Participant ceases to be such for any reason. Until otherwise determined by the Committee for all options to be granted on an Enrollment Date, the period referred to in clause (b) in the preceding sentence shall mean the period from the applicable Enrollment Date through the last business day prior to the immediately following Enrollment Date.

5.3 Number of Shares Subject to Option. The number of shares available for purchase by each Participant under the option will be established by the Committee from time to time prior to an Enrollment Date for all options to be granted on such Enrollment Date.

5.4 Other Terms and Conditions. Each option shall be subject to the following additional terms and conditions:

(a) payment for shares purchased under the option shall be made only through payroll withholding under Section 4.2;

(b) purchase of shares upon exercise of the option will be accomplished only in accordance with Section 6.1;

(c) the price per share under the option will be determined as provided in Section 6.1; and

(d) the option in all respects shall be subject to such other terms and conditions (applied on a uniform and nondiscriminatory basis), as the Committee shall determine from time to time in its discretion.

SECTION 6

PURCHASE OF SHARES

6.1 Exercise of Option. Subject to Section 6.2, on each Purchase Date, the funds then credited to each Participant’s account shall be used to purchase whole shares of Common Stock. Any cash remaining after whole shares of Common Stock have been purchased shall be carried forward in the Participant’s account for the purchase of shares on the next Purchase Date. The price per share of the shares purchased under any option granted under the Plan shall be eighty-five percent (85%) of the lower of:

(a) the last quoted per share selling price for shares of Common Stock on the Grant Date for such option, or if there were no sales on such date, the last quoted per share price for shares on the most recent preceding date on which there were sales of shares of common stock; or

(b) the last quoted per share selling price for shares of Common Stock on the Purchase Date or if there were no sales on such date, the last quoted per share price for shares on the most recent preceding date on which there were sales of shares of common stock.

Notwithstanding the foregoing, the maximum number of shares purchasable by any Participant on any one Purchase Date for any offering period shall not exceed 1,000 shares (subject to adjustment under Section 3.2 and change pursuant to Section 5.3), and any amount not applied to the purchase of shares on behalf of a Participant by reason of such limitation shall be refunded to that Participant.

6.2 Delivery of Shares. As directed by the Committee in its sole discretion, shares purchased on any Purchase Date shall be delivered directly to the Participant or to a custodian or broker (if any) designated by the Committee to hold shares for the benefit of the Participants. As determined by the Committee from time to time, such shares shall be delivered as physical certificates or by means of a book entry system.

6.3 Exhaustion of Shares. If at any time the shares available under the Plan are over-enrolled, enrollments shall be reduced proportionately to eliminate the over-enrollment. Such reduction method shall be “bottom up,” with the result that all option exercises for one share shall be satisfied first, followed by all exercises for two shares, and so on, until all available shares have been exhausted. Any funds that, due to over-enrollment, cannot be applied to the purchase of whole shares shall be refunded to the Participants (without interest thereon).

6.4 Accrual Limitations. No Participant shall be entitled to accrue rights to acquire shares of Common Stock pursuant to any purchase right outstanding under this Plan if and to the extent such accrual, when aggregated with rights accrued under other purchase rights outstanding under this Plan and similar rights accrued under other

employee stock purchase plans (within the meaning of Section 423 of the Code) of the Company or any of its Subsidiaries, would otherwise permit such Participant to purchase more than Twenty-Five Thousand U.S. Dollars (US$25,000) worth of stock of the Company or any Subsidiary (determined on the basis of the fair market value of such stock on the date or dates such rights are granted to the Participant) for each calendar year such rights are at any time outstanding. For purposes of applying the accrual limitations of this Section 6.4, the right to acquire shares of Common Stock pursuant to each purchase right outstanding under the Plan shall accrue as follows: (i) the right to acquire Shares of Common Stock under each such purchase right shall accrue as and when the purchase right first becomes exercisable during the calendar year; and (ii) no right to acquire shares of Common Stock under any outstanding purchase right shall accrue to the extent the Participant has already accrued in the same calendar year the right to acquire Twenty-Five Thousand U.S. Dollars (US$25,000) worth of shares of Common Stock (determined on the basis of the fair market value on the date or dates of grant) pursuant to one or more purchase rights held by the Participant during such calendar year. If by reason of this Section 6.4, one or more purchase rights of a Participant do not accrue for a particular purchase period, then the payroll deductions which the Participant made during that purchase period with respect to such purchase rights shall be promptly refunded in the currency originally collected. In the event there is any conflict between the provisions of this Section 6.4 and one or more provisions of the Plan or any instrument issued thereunder, the provisions of this Section 6.4 shall be controlling.

SECTION 7

WITHDRAWAL

7.1 Withdrawal. A Participant may withdraw from the Plan by submitting a completed Employee Stock Purchase Plan Authorization form to the Company in such form and manner prescribed by the Company (in its discretion and on a uniform and nondiscriminatory basis). A withdrawal will be effective only if it is received by the Company by the deadline specified by the Committee (in its discretion and on a uniform and nondiscriminatory basis) from time to time. When a withdrawal becomes effective, the Participant’s payroll contributions shall cease and all amounts then credited to the Participant’s account shall be distributed to him or her (without interest thereon).

SECTION 8

CESSATION OF PARTICIPATION

8.1 Termination of Status as Eligible Employee. A Participant shall cease to be a Participant immediately upon the cessation of his or her status as an Eligible Employee (for example, because of his or her termination of employment from all Employers for any reason). As soon as practicable after such cessation, the Participant’s payroll contributions shall cease and all amounts then credited to the Participant’s account shall be distributed to him or her (without interest thereon). If a Participant is on a Company-approved leave of absence, his or her participation in the Plan shall continue for so long as he or she remains an Eligible Employee and has not withdrawn from the Plan pursuant to Section 7.1.

SECTION 9

DESIGNATION OF BENEFICIARY

9.1 Designation. Each Participant may, pursuant to such uniform and nondiscriminatory procedures as the Committee may specify from time to time, designate one or more beneficiaries to receive any amounts credited to the Participant’s account at the time of his or her death. Notwithstanding any contrary provision of this Section 9, Sections 9.1 and 9.2 shall be operative only after (and for so long as) the Committee determines (on a uniform and nondiscriminatory basis) to permit the designation of beneficiaries.

9.2 Changes. A Participant may designate different beneficiaries (or may revoke a prior beneficiary designation) at any time by delivering a new designation (or revocation of a prior designation) in like manner. Any designation or revocation shall be effective only if it is received by the Committee. However, when so received, the designation or revocation shall be effective as of the date the designation or revocation is executed (whether or not the Participant still is living), but without prejudice to the Committee on account of any payment made before the change is recorded. The last effective designation received by the Committee shall supersede all prior designations.

9.3 Failed Designations. If a Participant dies without having effectively designated a beneficiary, or if no beneficiary survives the Participant, the Participant’s account shall be payable to his or her estate.

SECTION 10

ADMINISTRATION

10.1 Plan Administrator. The Plan shall be administered by the Committee. The Committee shall have the authority to control and manage the operation and administration of the Plan.

10.2 Actions by Committee. Each decision of a majority of the members of the Committee then in office shall constitute the final and binding act of the Committee. The Committee may act with or without a meeting being called or held and shall keep minutes of all meetings held and a record of all actions taken by written consent.

10.3 Powers of Committee. The Committee shall have all powers and discretion necessary or appropriate to supervise the administration of the Plan and to control its operation in accordance with its terms, including, but not by way of limitation, the following discretionary powers:

(a) To interpret and determine the meaning and validity of the provisions of the Plan and the options and to determine any question arising under, or in connection with, the administration, operation or validity of the Plan or the options;

(b) To determine any and all considerations affecting the eligibility of any employee to become a Participant or to remain a Participant in the Plan;

(c) To cause an account or accounts to be maintained for each Participant;

(d) To determine the time or times when, and the number of shares for which, options shall be granted;

(e) To establish and revise an accounting method or formula for the Plan;

(f) To designate a custodian or broker to receive shares purchased under the Plan and to determine the manner and form in which shares are to be delivered to the designated custodian or broker;

(g) To determine the status and rights of Participants and their beneficiaries or estates;

(h) To employ such brokers, counsel, agents and advisers, and to obtain such broker, legal, clerical and other services, as it may deem necessary or appropriate in carrying out the provisions of the Plan;

(i) To establish, from time to time, rules for the performance of its powers and duties and for the administration of the Plan;

(j) To adopt such procedures and sub plans as are necessary or appropriate to permit participation in the Plan by employees who are foreign nationals or employed outside of the United States;

(k) To delegate to any one or more of its members or to any other person, severally or jointly, the authority to perform for and on behalf of the Committee one or more of the functions of the Committee under the Plan.

10.4 Decisions of Committee. All actions, interpretations, and decisions of the Committee shall be conclusive and binding on all persons, and shall be given the maximum possible deference allowed by law.

10.5 Administrative Expenses. All expenses incurred in the administration of the Plan by the Committee, or otherwise, including legal fees and expenses, shall be paid and borne by the Employers, except any stamp duties or transfer taxes applicable to the purchase of shares may be charged to the account of each Participant. Any brokerage fees for the purchase of shares by a Participant, fees and taxes (including brokerage fees) for the transfer, sale or resale of shares by a Participant, or the issuance of physical share certificates, shall be borne solely by the Participant.

10.6 Eligibility to Participate. No member of the Committee who is also an employee of an Employer shall be excluded from participating in the Plan if otherwise eligible, but he or she shall not be entitled, as a member of the Committee, to act or pass upon any matters pertaining specifically to his or her own account under the Plan.

10.7 Indemnification. Each of the Employers shall, and hereby does, indemnify and hold harmless the members of the Committee and the Board, from and against any and all losses, claims, damages or liabilities (including attorneys’ fees and amounts paid, with the approval of the Board, in settlement of any claim) arising out of or resulting from the implementation of a duty, act or decision with respect to the Plan, so long as such duty, act or decision does not involve gross negligence or willful misconduct on the part of any such individual.

SECTION 11

AMENDMENT, TERMINATION, AND DURATION

11.1 Amendment, Suspension, or Termination. The Board, in its sole discretion, may amend, suspend or terminate the Plan, or any part thereof, at any time and for any reason. If the Plan is terminated, the Board, in its discretion, may elect to terminate all outstanding options either immediately or upon completion of the purchase of shares on the next Purchase Date, or may elect to permit options to expire in accordance with their terms (and participation to continue through such expiration dates). If the options are terminated prior to expiration, all amounts then credited to Participants’ accounts which have not been used to purchase shares shall be returned to the Participants (without interest thereon) as soon as administratively practicable.

11.2 Duration. The Plan shall commence on the Effective Date, and subject to Section 11.1 (regarding the Board’s right to amend, suspend or terminate the Plan), shall remain in effect for ten (10) years from the earlier of the date of its adoption by the Board and the date of its approval by the Company’s stockholders.

SECTION 12

GENERAL PROVISIONS

12.1 Participation by Subsidiaries. One or more Subsidiaries of the Company may become participating Employers by adopting the Plan and obtaining approval for such adoption from the Board. By adopting the Plan, a Subsidiary shall be deemed to agree to all of its terms, including (but not limited to) the provisions granting exclusive authority (a) to the Board to amend the Plan, and (b) to the Committee to administer and interpret the Plan. An Employer may terminate its participation in the Plan at any time. The liabilities incurred under the Plan to the Participants employed by each Employer shall be solely the liabilities of that Employer, and no other Employer shall be liable for benefits accrued by a Participant during any period when he or she was not employed by such Employer.

12.2 Inalienability. In no event may either a Participant, a former Participant or his or her beneficiary, spouse or estate sell, transfer, anticipate, assign, hypothecate, or otherwise dispose of any right or interest under the Plan; and such rights and interests shall not at any time be subject to the claims of creditors nor be liable to attachment, execution or other legal process. Accordingly, for example, a Participant’s interest in the Plan is not transferable pursuant to a domestic relations order.

12.3 Severability. In the event any provision of the Plan shall be held illegal or invalid for any reason, the illegality or invalidity shall not affect the remaining parts of the Plan, and the Plan shall be construed and enforced as if the illegal or invalid provision had not been included.

12.4 Requirements of Law. The granting of options and the issuance of shares shall be subject to all applicable laws, rules, and regulations, and to such approvals by any governmental agencies or securities exchanges as the Committee may determine are necessary or appropriate.

12.5 Compliance with Rule 16b-3. Any transactions under this Plan with respect to officers (as defined in Rule 16a-1 promulgated under the 1934 Act) are intended to comply with all applicable conditions of Rule 16b-3. To the extent any provision of the Plan or action by the Committee fails to so comply, it shall be deemed null and void, to the extent permitted by law and deemed advisable by the Committee. Notwithstanding any contrary provision of the Plan, if the Committee specifically determines that compliance with Rule 16b-3 no longer is required, all references in the Plan to Rule 16b-3 shall be null and void.

12.6 No Enlargement of Employment Rights. Neither the establishment or maintenance of the Plan, the granting of options, the purchase of shares, nor any action of any Employer or the Committee, shall be held or construed to confer upon any individual any right to be continued as an employee of the Employer nor, upon dismissal, any right or interest in any specific assets of the Employers other than as provided in the Plan. Each Employer expressly reserves the right to discharge any employee at any time, with or without cause.

12.7 Apportionment of Costs and Duties. All acts required of the Employers under the Plan may be performed by the Company for itself and its Subsidiaries, and the costs of the Plan may be equitably apportioned by the Committee among the Company and the other Employers. Whenever an Employer is permitted or required under the terms of the Plan to do or perform any act, matter or thing, it shall be done and performed by any officer or employee of the Employers who is thereunto duly authorized by the Employers.

12.8 Construction and Applicable Law. The Plan is intended to qualify as an “employee stock purchase plan” within the meaning of Section 423(b) of the Code. Any provision of the Plan which is inconsistent with Section 423(b) of the Code shall, without further act or amendment by the Company or the Committee, be reformed to comply with the requirements of Section 423(b). The provisions of the Plan shall be construed, administered and enforced in accordance with such Section and with the laws of the State of Delaware (excluding Delaware’s conflict of laws provisions).

12.9 Captions. The captions contained in and the table of contents prefixed to the Plan are inserted only as a matter of convenience, and in no way define, limit, enlarge or describe the scope or intent of the Plan nor in any way shall affect the construction of any provision of the Plan.

EXECUTION

IN WITNESS WHEREOF, Varian Medical Systems, Inc., by its duly authorized officer, has executed this Plan.