Exhibit 10.1March 15, 2006Mr. Peter LoescherDear Peter:On behalf of Merck & Co., Inc. (“Merck”), it is my pleasure to extend you the offer of employmentfor the position of President, Global Human Health**.**In this position, you will report to me atWhitehouse Station. Our offer includes the following:**Total Compensation****Base Salary**: You will be paid a gross monthly salary of $91,667, which equates to $1,100,004 onan annual basis. Your salary will be reviewed annually. The date of your first merit increase,if any, will be March 1, 2007.**Executive Incentive Plan**: You will be eligible to participate in Merck’s Executive IncentivePlan (EIP), subject to the terms of the plan. The target bonus for your position is 105% ofyour annual base salary. The bonus is discretionary and the amount of the bonus, if any isawarded, depends on individual performance, division performance and corporate performance.Notwithstanding the preceding sentence, the Compensation and Benefits Committee of the Board ofDirectors of Merck & Co., Inc. (the “Compensation and Benefits Committee”) has approved aguaranteed bonus for you for Performance Year 2006 of 118% of your annual base salary. Based onthe level of your job within the Company, you will have the opportunity within the first 30calendar days of the first day of your employment (provided that your first day is no later thanDecember 1, 2006) to elect to defer all or part of the EIP bonus you will receive forPerformance Year 2006. This 30-day period represents your only opportunity to elect an EIPdeferral for Performance Year 2006. Information about the Deferral Program and instructionspertaining to this election will be contained in your new-hire materials when you join theCompany. If you do not receive Deferral Program information and instructions, please contactthe Merck Benefits Center at 800-66MERCK (800-666-3725).**Long-Term Incentive (LTI) Program**: Starting in 2006, you will be eligible for consideration forannual grants of stock-based incentives under the Merck & Co., Inc. Incentive Stock Plan. (Thenext annual grant date is expected to be in February 2007.) In any given year, our incentivesmay include stock options, performance share units (PSUs), restricted stock units (RSUs) or anycombination thereof, with the number and proportion of shares covered by such incentivesdetermined by the Compensation and Benefits Committee. For illustrative purposes, a typicalgrant for a position at your job level would be in the range of 96,000 stock options, 18,000PSUs and 18,000 RSUs. Currently, annual grants of Merck stock options vest in equalinstallments over three years; PSUs have a three-year performance period; and RSUs have athree-year restriction period. Distribution of shares in connection with both PSUs and RSUs isdependent on continued employment with the Company; additionally, the level of payout associatedwith PSUs is contingent on Company performance. Please note that terms and conditions of anyfuture grants may change from time to time. The specific terms and conditions of your grantswill be provided at the time the grants are made to you. Based on your job level within the Company, you will be covered by Merck’s stock ownershipguidelines. The guidelines are intended to reinforce our philosophy concerning “ownership” and,in a concrete way, quantify our expectations concerning ownership of Merck stock. Based on yourjob level within the Company, the guidelines provide that you should acquire Merck stock,over time, equal in value to five times your annual base salary. Importantly, the LTI program –and retention of shares earned in connection therewith – is intended to facilitate theacquisition of shares. Also, there is currently no time frame under which you will be requiredto achieve the multiple of salary.
 

 
Mr. Peter Loescher