While effectiveness of ultrasound in diagnosis of stone in gall bladder and common bile duct has been well established, role of ultrasound in detection of intrahepatic bile duct stone has rarely been described. However, in ultrasonographic diagnosis of common bile duct and gall bladder stone, evaluation of intrahepatic bile duct is essential to dectease the incidence of residual stone because about 5-18% of common bile duct and/or gall bladder stone also have in intrahepatic bile duct. We studied 27 cases of intrahepatic bile duct stone diagnosed with ultrasound for recent 14 months from September 1983 to November 1984 at Department of Radiology, Seoul National University, and analysed ultrasonographic findings of the stones. The results were as follows; 1. In 27 cases out of total 35 cases(77.1%), intrahepatic duct stones were confirmend by operation, postoperative T-tube cholarigiography, ERCP, PTC, and CT; in 4 cases(11.4%), there were no stone in hepatic duct; and in 4 cas s(11.4%) intrahepatic ducts were not completely evaluated because of incomplete studies. 2. 17 cases ut of 27 cases with proven intrahepatic duct stones had also common bile duct and/or gall bladder stones(63%). 3. Ultrasound showed echogenic material (from dut to mass) in 27 cases(100%), posterior shadowing in 26 cases(96%), and ductal dilatation in 23 cases(85%). 4. Intrahepatic stones tend to be apeared as mass-like echogenecity, with the increase in size, number and degree of agregation of stones.