The "Endomedix Laparoscan" and the "Leopard" and "Panther" intraoperative ultrasounds were successfully used for the detection of unsuspected common bile duct stones during laparoscopic cholecystectomy (LC). Out of 60 patients six had common bile duct (CBD) stones and in one patient sludge has been seen. In patients with CBD stones, four small calculi have been observed in one patient, despite negative intraoperative cholangiography (IC). In an other patient a stone in the retropancreatic part of the CBD was detected. Based on preoperative findings CBD stone was unsuspected. We found that intraoperative ultrasound (IOUS) is useful for in investigating the CBD to detect unsuspected common bile duct stones. It can be used for the examination of other organs (liver, pancreas, hepatoduodenal ligament) as well. The method is easy to perform, fairly simple and informative so it can replace IC during laparoscopic cholecystectomy.