UNITED STATES SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 11-K

ANNUAL REPORT
Pursuant to Section 15(d) of the
Securities Exchange Act of 1934

(Mark One)

þ		ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2006

o		TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from                      to                     

MERCK & CO., INC.

(Name of issuer of the securities held pursuant to the plan)

One Merck Drive
P.O. Box 100
Whitehouse Station, New Jersey 08889-0100

(Address of principal executive office)

 

 

Merck & Co., Inc.
Employee Savings and Security Plan

Employer Identification Number: 22-1109110
Plan Number: 001
Index

		Page
Report of Independent Registered Public Accounting Firm		1
Financial Statements:
Statements of Net Assets Available for Benefits as of December 31, 2006 and 2005		2
Statement of Changes in Net Assets Available for Benefits for the Year Ended December 31, 2006		3
Notes to Financial Statements		4 - 7
Supplemental Schedule*:
H — Line 4i — Schedule of Assets (Held at End of Year)		8
Signature		9
Exhibit Index		10
Exhibit 23 — Consent of Independent Registered Public Accounting Firm		11

Report of Independent Registered Public Accounting Firm

To the Participants and Administrator of
Merck & Co., Inc. Employee Savings and Security Plan

In our opinion, the accompanying statements of net assets available for benefits and the related statement of changes in net assets available for benefits present fairly, in all material respects, the net assets available for benefits of Merck & Co., Inc. Employee Savings and Security Plan (the “Plan”) at December 31, 2006 and 2005, and the changes in net assets available for benefits for the year ended December 31, 2006 in conformity with accounting principles generally accepted in the United States of America. These financial statements are the responsibility of the Plan’s management. Our responsibility is to express an opinion on these financial statements based on our audits. We conducted our audits of these statements in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for our opinion.

Our audits were conducted for the purpose of forming an opinion on the basic financial statements taken as a whole. The supplemental Schedule of Assets (Held at End of Year) as of December 31, 2006, is presented for the purpose of additional analysis and is not a required part of the basic financial statements but is supplementary information required by the Department of Labor’s Rules and Regulations for Reporting and Disclosure under the Employee Retirement Income Security Act of 1974. This supplemental schedule is the responsibility of the Plan’s management. The supplemental schedule has been subjected to the auditing procedures applied in the audits of the basic financial statements and, in our opinion, is fairly stated in all material respects in relation to the basic financial statements taken as a whole.

/s/ PricewaterhouseCoopers LLP

Florham Park, New Jersey
June 18, 2007

Merck & Co., Inc.
Employee Savings and Security Plan

Statements of Net Assets Available for Benefits

		December 31,
		2006				2005
Assets
Investments
Investment in the Master Trust		$	3,595,468,293			$	2,984,052,736
Participant loans			37,274,460				37,519,077
Total investments			3,632,742,753				3,021,571,813
Receivables
Employer contribution			7,133,134				6,704,706
Participant contribution			17,026,291				15,710,064
Accrued interest and dividends			6,942,180				7,018,941
Total receivables			31,101,605				29,433,711
Net assets available for benefits		$	3,663,844,358			$	3,051,005,524

The accompanying notes are an integral part of these financial statements.

Merck & Co., Inc.
Employee Savings and Security Plan

Statement of Changes in Net Assets Available for Benefits

		Year Ended
		December 31,
		2006
Additions to net assets attributed to
Investment gain from the Master Trust
Net appreciation in fair value of investments		$	414,260,906
Interest and dividends			137,148,109
Net investment gain			551,409,015
Contributions to the Plan
By participants			222,674,150
By employer			88,782,822
Total contributions			311,456,972
Transfers in			2,092,979
Total additions			864,958,966
Deductions from net assets attributed to
Benefits paid to participants			(251,984,902	)
Transfers out			(135,230	)
Total deductions			(252,120,132	)
Net increase			612,838,834
Net assets available for benefits
Beginning of year			3,051,005,524
End of year		$	3,663,844,358

The accompanying notes are an integral part of these financial statements.

Merck & Co., Inc.
Employee Savings and Security Plan

Notes to Financial Statements

1.		Description of Plan
		The following description of the Merck & Co., Inc. Employee Savings and Security Plan (the “Plan”) provides only general information. Participants should refer to the Plan document for a more complete description of the Plan’s provisions.
		General
		The Plan was designed to provide an easy, economical way for employees to become stockholders of Merck & Co., Inc. (the “Company” or “Merck”) as well as a systematic means of saving and investing for the future. Regular full-time, part-time, and temporary employees of the Company and of certain wholly-owned subsidiaries as defined by the Plan document who are not covered by a collective bargaining agreement are eligible to enroll in the Plan on or after the first day of the month following their date of hire.
		The Plan is administered by a management committee appointed by the Company’s Chief Executive Officer or Compensation and Benefits Committee of its Board of Directors.
		The Plan is subject to the provisions of the Employee Retirement Income Security Act of 1974 (“ERISA”).
		Master Trust
		The assets of the Plan are maintained, for investment purposes only, on a commingled basis with the assets of the Merck & Co., Inc. Employee Stock Purchase & Savings Plan in the Merck & Co., Inc. Employee Savings & Security Plan and the Merck & Co., Inc. Employee Stock Purchase & Savings Plan Trust (the “Master Trust”). The plans do not own specific Master Trust assets but rather maintain individual beneficial interests in such assets. The portion of fund assets allocable to each plan is based upon the participants’ account balance within each plan. Investment income for each fund is allocated to each plan based on the relationship of each plan’s beneficial interest in the fund to the total beneficial interest of all plans in the fund.
		Contributions
		Participants may contribute from 2% up to 25% of their base pay. Employees earning less than $90,000 may contribute a maximum of 25% of base pay. Employees earning $90,000 or more are limited to maximum contributions of 15% of base pay. However, pre-tax contributions cannot exceed the statutory limit for pre-tax deferrals ($15,000 in 2006). In addition, the Company matches 75% of an employee’s contributions up to a maximum of 6% of base pay per pay period. Company matching contributions are invested according to a participant’s elections.
		Age 50 and above — In addition, the Plan permits unmatched pre-tax “catch-up contributions” of up to $5,000 for 2006 by participants who are at least age 50 by year end.
		Participants direct the investment of their contributions into any fund investment option available under the Plan, including the Merck Common Stock Fund. During 2006, the Plan offered 16 mutual funds, a commingled fund, a separately managed fund and the Merck Common Stock Fund.

Merck & Co., Inc.
Employee Savings and Security Plan

Notes to Financial Statements

		Participant Accounts
		Each participant’s account is credited with the participant’s contribution, the Company’s matching contribution and an allocation of Plan earnings. The allocation is based on participants’ account balances, as defined in the Plan document.
		Vesting
		Participants are immediately vested in their contributions, all Company matching contributions, plus actual earnings thereon.
		Participant Loans
		Participants may borrow from their account balances with interest charged at the prime rate plus 1%. Loan terms range from one to five years for a short term loan or up to thirty years for the purchase of a primary residence. The minimum loan is $500 and the maximum loan is the lesser of (i) $50,000 less the highest outstanding loan balance(s) during the one year period prior to the new loan application date, or (ii) 50% of the participant’s account balance less any current outstanding loan balance and defaulted loan amounts.
		Payment of Benefits
		In-service (which include hardship withdrawals) and termination distributions are made throughout the year in accordance with applicable Plan provisions.
		Other Matters
		Transfers in and out during 2006 primarily relate to transfers between the Plan and the Merck & Co., Inc. Employee Stock Purchase and Savings Plan for employees who changed their status during the year.
2.		Summary of Accounting Policies
		Basis of Accounting
		The accompanying financial statements are prepared on the accrual basis of accounting.
		Use of Estimates
		The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Management believes that these estimates are adequate. Actual results could differ from those estimates.
		Investment Valuation and Income Recognition
		Valuation of investments of the Plan represents the Plan’s allocable portion of the Master Trust. Quoted market prices are used to value investments. Shares of mutual funds are valued at the net asset value of shares held by the Master Trust at year end. For the commingled and separately managed funds within the Master Trust, the investment units are based on the current market values of the underlying assets of the fund. Participant loans are valued at their outstanding balances.

Merck & Co., Inc.
Employee Savings and Security Plan

Notes to Financial Statements

		Purchases and sales of securities are recorded on a trade-date basis. Dividend income is recorded on the ex-dividend date.
		Contributions
		Employee and Company matching contributions are recorded in the period in which the Company makes the payroll deductions from the participants’ earnings.
		Payment of Benefits
		Benefits are recorded when paid.
		Expenses
		The Plan’s administrative expenses are paid by the Company.
		Risks and Uncertainties
		The Plan provides for various investment options in investment securities. Investment securities, in general, are exposed to various risks, such as interest rate, credit and overall market volatility. Due to the level of risk associated with certain investment securities, it is reasonably possible that changes in the values of investment securities will occur in the near term and that such changes could materially affect participants’ account balances and the amounts reported in the statement of net assets available for benefits.
3.		Related-Party Transactions
		Certain Plan investments are shares of mutual funds managed by Fidelity Management Trust Company (“Fidelity”). Fidelity is the trustee as defined by the Plan and, therefore, these transactions qualify as party-in-interest transactions. The total market value of investments in the mutual funds managed by Fidelity was $829,345,318 and $668,837,111 at December 31, 2006 and December 31, 2005, respectively.
		Merck & Co., Inc. also is a party-in-interest to the Plan under the definition provided in Section 3(14) of ERISA. Therefore, Merck Common Stock Fund transactions qualify as party-in-interest transactions. The market value of investments in the Merck Common Stock Fund was $801,341,057 and $587,754,541 at December 31, 2006 and December 31, 2005, respectively.
4.		Plan Termination
		Although it has not expressed any intent to do so, the Company has the right under the Plan to discontinue its contributions at any time and to terminate the Plan subject to the provisions of ERISA. Upon termination of the Plan, each participant thereby affected would receive the entire value of his or her account as though he or she had retired as of the date of such termination.

Merck & Co., Inc.
Employee Savings and Security Plan

Notes to Financial Statements

5.		Tax Status
		The Plan obtained a tax determination letter from the Internal Revenue Service dated August 20, 2003 indicating that it had been designed in accordance with applicable sections of the Internal Revenue Code (“IRC”). However, the Plan has been amended since the receipt of the determination letter. The Plan sponsor and legal counsel believe that the Plan is designed and currently operates in compliance with the IRC. Therefore, no provision for income taxes has been made.
6.		Master Trust
		The Plan had an approximate 92% and 91% interest in the Master Trust at December 31, 2006 and December 31, 2005 respectively. The net assets of the Master Trust are as follows:

		December 31,
		2006				2005
Mutual Funds		$	2,244,486,627			$	2,043,270,222
Commingled and Separately Managed Funds			749,397,294				536,679,881
Merck Common Stock Fund			922,164,315				680,857,190
Accrued interest and dividends			7,989,452				8,144,971
		$	3,924,037,688			$	3,268,952,264

Total investment income of the Master Trust for the year ended December 31, 2006 is as follows:

		Year Ended
		December 31,
		2006
Investment income, net
Interest and dividends		$	150,532,642
Net appreciation in Mutual Funds			131,696,678
Net appreciation in Commingled and Separately Managed Funds			80,925,360
Net appreciation in Merck Common Stock Fund			247,982,701
Total investment income		$	611,137,381

Merck & Co., Inc.
Employee Savings and Security Plan

		Schedule H
Line 4i — Schedule of Assets (Held at End of Year)		EIN: 22-1109110
December 31, 2006		Plan No.: 001

				(c) Description of Investment Including
(a)		(b) Identity of Issuer, Borrower,		Maturity date, Rate of Interest, Collateral,		(d) Cost		(e) Current
		Lessor or Similar Party		Par or Maturity Value				Value
		Master Trust		Investment in Master Trust		—		$	3,595,468,293
*		Participant Loans		Interest rates ranging from 5% to 12.5% and with maturities through 2037		—			37,274,460
				Total				$	3,632,742,753

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the undersigned plan administrator has duly caused this annual report to be signed on behalf of the Merck & Co., Inc. Employee Savings and Security Plan by the undersigned hereunto duly authorized.

June 20, 2007

EXHIBIT INDEX

Exhibit
Number				Document		Page
	23			Consent of Independent Registered Public Accounting Firm			11