May same-restaurant sales were up 2.8 percent in the United States, helped by new coffee drinks and snacks.
The world's largest hamburger chain is one of the restaurant industry's top performers largely because its Dollar Menu has been attracting diners amid a lengthy recession that has sent unemployment sharply higher.
The stronger U.S. dollar -- which lessens the dollar value of overseas sales -- led to an overall 0.4 percent decline at worldwide McDonald's restaurants, the company said. Sales rose 7 percent in constant currencies.
Fast-food restaurants generally have held up better in a tough economy than higher-priced sit-down restaurants.
McDonald's May same-store sales increased 7.6 percent in Europe, and 6.4 percent in the company's Asia/Pacific, Middle East and Africa segment.
Its shares fell 2.8 percent in premarketing trading to $58.17 from Friday's closing price of $59.87 on the New York Stock Exchange.
(Reporting by Ben Klayman and Lisa Baertlein in Los Angeles; Editing by Maureen Bavdek)