Sales in stores open at least one year, a measure known as same-store sales, rose 2.8 percent at Wal-Mart Stores and 4.2 percent at Sam's Club for the four weeks ended Aug. 29.
Analysts polled by Thomson Reuters predicted a 1.6 percent rise.
Including fuel, the world's largest retailer's total same-store sales rose 3.5 percent.
Total sales at Wal-Mart Stores Inc. rose 9 percent to $30.67 billion in the four-week period.
The Bentonville, Ark.-based company says sales of groceries, health and wellness products and flat-panel TVs sold well, as did back-to-school product such as jeans and school supplies.
