Martin Marietta Materials, Inc. Increases Regular Cash Dividend 15% to 23 Cents Per Share

RALEIGH, North Carolina (August 17, 2005) -- Stephen P. Zelnak, Jr., Chairman and Chief Executive Officer of Martin Marietta Materials, Inc. (NYSE:MLM), today announced that the Board of Directors has declared an increase in the regular quarterly cash dividend to $0.23 per share on the Corporation's common stock. This dividend, which represents a cash dividend of $0.92 per share on an annualized basis, is payable September 30, 2005, to shareholders of record at the close of business on September 1, 2005, and reflects a 15% increase over the previous annualized amount.

Commenting on the dividend increase Zelnak stated, "Our strong cash position and excellent operating performance provide us the ability to increase shareholder returns through the dividend payout. The increase announced today is in line with our previous target average dividend payout range of 25 to 30 percent of earnings over the course of an economic cycle. We will continue to evaluate further ways to utilize our cash position to provide benefits to our shareholders."

Martin Marietta is the nation's second largest producer of construction aggregates, a leading producer of magnesia-based chemical products and is developing structural composites products for use in a wide variety of industries.