The Marsh & McLennan Companies 401(k) Savings & Investment Plan (the "Plan") is a convenient way to help achieve your long-term savings and investment goals. The Plan is a profit sharing plan with an employee stock ownership feature and a 401(k) component, designed to encourage saving through a number of investment opportunities, including the opportunity to invest in the MMC Stock Fund (a fund comprised principally of Marsh & McLennan Companies, Inc. common stock (par value of $1.00 per share)).

Under the Plan, you may save and invest for the future by contributing on a before-tax and/or after-tax basis. You can direct your future contributions and your Company Matching Contributions (which begin after you complete one year of service) into any of the funds in the Plan's investment lineup.

Plan participation involves investment risk. If the value of MMC stock and other Plan assets decreases or increases, the value of your accounts in the Plan will also decrease or increase. Under this type of Plan, you assume responsibility for the investment choices you make for your account.

This section describes the Plan provisions as of June 6, 2008, and applies if you are employed by the Company on or after June 6, 2008.

As used throughout this document, "employee," "you" and "your" always mean a U.S. salaried employee of MMC or any subsidiary or affiliate of MMC (other than Kroll) or, effective June 6, 2008, a U.S. regular employee of Kroll or any subsidiary or affiliate of Kroll. Individuals classified on payroll as hourly, who are leased employees, who are compensated as independent contractors, who are employed in Puerto Rico, or who are interns are not eligible to participate.

In this description of the 401(k) Savings & Investment Plan, the term "Company" sometimes refers to MMC and all participating employers.

This section, together with the Investment Return Fact Sheet and the Administrative Information section, also constitute part of a prospectus covering securities that have been registered under the Securities Act of 1933, as amended. See below for more details.

The Plan was most recently approved by the Internal Revenue Service as tax qualified under Sections 401(a) and 4975(e)(7) of the Internal Revenue Code by means of a favorable determination letter dated February 7, 2006. Accordingly, MMC's contributions will be deductible by MMC within the limits set forth in the Internal Revenue Code. This section describes the Plan provisions as of June 6, 2008 which apply if you are employed on or after June 6, 2008. Former employees may be subject to other rules under prior provisions.

The date of this prospectus is June 6, 2008

Participants may receive, without charge, upon request to the Plan Administrator, any of the documents that constitute part of the prospectus, as well as a copy of the annual report from Marsh & McLennan Companies, Inc. ("MMC"), copies of other reports, proxy statements and other communications distributed to MMC shareholders, and the annual report for the Plan. Copies of the documents described may be obtained from the Plan Administrator at the following address:

MMC's annual report can be viewed at www.mmc.com/annualreport.html.

All reports and other documents subsequently filed by MMC or the Plan pursuant to Section 13(a), 13(c), 14, 15(d) of the Securities Exchange Act of 1934, as amended, prior to the filing of a post-effective amendment which indicates that all securities offered have been sold or which deregisters all securities then remaining unsold, also will be deemed to be incorporated into this Summary Plan Description and Prospectus from the date of the filing or such reports and documents.