A case of Bouveret's syndrome with obstruction of the duodenojejunal flexure diagnosed preoperatively by sonography is presented. A 48-year-old man with a history of cholelithiasis presented with colicky pain of 2 days' duration. Real-time sonography revealed a fluid-distended stomach and duodenum and a 3.4-cm bright curvilinear echo with dense shadowing in the duodenojejunal flexure, suggesting a gallstone. In addition, there was pneumobilia and evidence of chronic cholecystitis. The findings were confirmed with CT, which showed a partially calcified gallstone at the duodenojejunal flexure, pneumobilia, and a fistulous communication between the gallbladder and duodenum. At surgery, a large gallstone was found impacted at the duodenojejunal flexure. The stone and gallbladder were successfully removed and the fistula repaired. The sonographic diagnosis of Bouveret's syndrome enabled early surgical intervention. (C) 2003 Wiley Periodicals, Inc.