McDonald's reported a fall in sales at established restaurants across all regions in August, the fifth such monthly drop since CEO Don Thompson took the helm in July 2012.
McDonald's shares fell nearly 1 percent in premarket trading. (Click here for the latest quote.)
The company said on Tuesday that worldwide sales at restaurants open at least 13 months fell 3.7 percent in August.
Analysts on average had expected a 3.1 percent drop in global same-restaurant sales, according to research firm Consensus Metrix.
In the United States, same-restaurant sales fell 2.8 percent. Monthly same-store sales have been down or flat in the region since November 2013.
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Thompson has presided over a period of disappointing results from the United States, due in part to internal missteps, competition from burger chains including Burger King Worldwide and Wendy's and cautious spending by the lower-income consumers that frequent the chain.
McDonald's is replacing its U.S. president for the second time in two years.
Same-restaurant sales in Europe, the company's biggest region by sales, fell 0.7 percent.
In Asia/Pacific, Middle East and Africa, sales fell 14.5 percent, hurt mainly by a food scandal in China that drove away diners and forced the chain to scramble to find new suppliers of ingredients for its Chicken McNuggets and Big Macs.
The company said it expects the food scare to hurt third-quarter profit by 15 cents to 20 cents per share.
Analysts on average were expecting a profit of $1.52 per share in the third quarter, according to Thomson Reuters I/B/E/S.
Consensus Metrix's estimates included a 2 percent decline in the United States, a 2.1 percent drop in Europe and a 10.1 percent drop in the Asia/Pacific, Middle East and Africa unit.
McDonald's shares closed at $92.50 on the New York Stock Exchange on Monday.