The Radiological analysis in normal and variations of hepatic duct system were performed on the 154 cases of surgically explored biliary disease patients from January, 1973 to December, 1977 for 5 years at Yonsei University Hospital. The analytic results are as follows: 1. In T-tube cholangiogram, normal variations, of intrahepatic duct by OHTO classification, the most common type was type I (66.3%) and type II (7.8%), type III (1.3%), type IV (7.8%), type V (10.4%) and other type (6.4%). 2. The highest incidence of age group was 41-50 years (27%), yet more than 75% cases were belong to the group after third decade. According to sex incidence, the female was slightly prevalent than male. 3. The causative diseases of 154 analyzed cases are, diseases of calculus; 118 cases congenital anomalies; 6 cases, neoplasm of biliary system; 6 cases, and parasitic diseases; 19 cases. 4. The T-tube cholangiogram was performed in 70% within 8-14 days after biliary operation. In cholangiogra , average diameter of CBD was measured 1.52cm during operation and was measured 1.39cm after operation. 5. Among 118 cases of biliary diseases associated with biliary duct stones, intrahepatic duct stones were about 5 percent and left intrahepatic stones were prevalent than right intrahepatic stones. 6. In oral or I.V. Cholangiogram prior to operation (87 cases from 154 cases), of each nonvisualization of gall bladder and CBD was 37 cases and 27 cases, were well visualized in gall bladder and CBD was 18 cases, and gall bladder and CBD stones were detectable in 18 cases. 7. In T-tube cholangiogram, the prominent findings were dilated biliary tree, normal biliary tree, cholangitic pattern, and residual stones in the intrahepatic and CBD in order of frequency.