Costco's same-store sales fall 4 percent
Same-store sales at its U.S. outlets fell 2 percent, while international division sales fell 11 percent.
Excluding gasoline price deflation U.S. comparable sales would have been up 2 percent, the company said.
Analysts on average were expecting the warehouse club operator to post a 3.7 percent decline, including fuel, according to Thomson Reuters data.
Net sales for the five weeks ended January 4 fell 2 percent to $7.4 billion.
The company, which competes with Wal-Mart Stores Inc's Sam's Club and BJ's Wholesale Club Inc , said demand was strong in its foods business but weak for non-foods in December, a key month for retailers.
Warehouse clubs like Costco were once viewed as a relatively safe haven amid beaten-down U.S. retail stocks, as shoppers sought out their discounted prices on food and toiletries.
But recent weakness has shown its business is not immune from a U.S. recession which has crimped the spending habits of most consumers.
(Reporting by Ratul Ray Chaudhuri in Bangalore; Editing by David Holmes)