Marathon Oil (MRO)

Voting instruction card must be signed and dated below.
— Please fold and detach card at perforation before mailing. —

These confidential voting instructions are to the Fidelity Management Trust Company, as Trustee for the United States Steel Corporation Savings Fund Plan for Salaried Employees (the "Plan"), and are solicited on behalf of the Board of Directors for the Annual Meeting of Stockholders to be held on Wednesday, April 27, 2005 at 10:00 A.M. Central Time in the Conference Center Auditorium of the Marathon Oil Tower, 5555 San Felipe Road, Houston, TX 77056.

The undersigned, as a participant in the Plan, hereby directs the Trustee to vote the number of shares of Marathon Oil Corporation common stock credited to the undersigned's account under the Plan at the Annual Meeting of Stockholders, and at any meeting resulting from an adjournment(s) or postponement(s) thereof, upon all subjects that may properly come before the meeting, including the matters described in the 2005 Proxy Statement, subject to any directions indicated on the reverse side. In the Trustee's discretion, it may vote upon such other matters as may properly come before the meeting.

You are cordially invited to attend the Annual Meeting of Stockholders on Wednesday, April 27, 2005.

The Meeting will be held in the Conference Center Auditorium of the Marathon Oil Tower, 5555 San Felipe Road, Houston, Texas 77056 at 10:00 A.M. Central Time.

(Please detach this card from your voting instruction card and bring it with you as identification. A map to the meeting site is inscribed on this card for your convenience. The use of an attendance card is for our mutual convenience, however your right to attend without an attendance card, upon proper identification, is not affected.)

William F. Schwind, Jr.
Secretary