Ultrasound is the modality of choice for the diagnosis of cholelithiasis and for the evaluation of the intra-and extra hepatic biliary tree in the patient with jaundice, but its role in the diagnosis of choledocholithiasis is less certain. We retrospectively examined 127 patients who had undergone ERCP by performing right upper quadrant sonography immediately prior to ERCP and undergone surgery due to biliary stone. We assessed th esize of the intra-and extrahepatic ducts adn presence or absence of calculi, and compared the detection rate of ultrasound with that of ERCP in the patient with biliary stone in order of gall bladder, extrahepatic duct, and intrahepatic duct. RESULT : 1. Of all 127 patients with biliary stone, female were 75. 6th decades were most common. 2. Each numbers of patients in the order of biliary location are 43 in gall blader, 17 in intrahepatic ducts, 23 in extrahepatic ducts, 44 in multiple locations. 3 Gall bladder stones were 81 in total and ultrasoun detected stones in 75 patients. ERCP-in 35 patients. 4. Extrahepatic duct stones were 54 in total and ultrasound detected stones in 31 patients . ERCP-in 49 patients. 5. Intrahepatic duct stones were 45 in total and ultrasound detected stones in 38 patients. ERCP-in 41 patients. In summary, Ultrasound in much more sensitive to detect GB stones than ERCP. ERCP is much more sensitive to detect extrahepatic duct stones than ultraosound. Sensitivity of ultrasound and ERCP were almost equal in the intrahepatic duct stones.