This study assessed the effectiveness of laparoscopic ultrasonography in demonstrating biliary anatomy, confirming suspected pathology, and detecting unsuspected pathology.Laparoscopic ultrasonography was performed on 48 patients (17 M:31 M) who underwent laparoscopic cholecystectomy. An Aloka 7.5-MHz linear laparoscopic ultrasound transducer was used for scanning.Gallbladder stones were confirmed by laparoscopic ultrasonography in all patients and unsuspected pathology was found in five patients. Two patients were found to have common bile duct stones by laparoscopic ultrasonography and this was confirmed by laparoscopic cholangiography. Laparoscopic ultrasound was found to be helpful during dissection in four patients, particularly in a patient with Mirizzi syndrome. The entire common bile duct was visualized by laparoscopic ultrasonography in 40 patients but was poorly seen in eight patients. The mean time taken for the examination was 9 min (range 4-18 min).Laparoscopic ultrasound is useful during laparoscopic cholecystectomy.