During the period of 4 years, sixteen case of choledochal cyst were proven surgically and then theradiological analysis and review of literatures were carried out on these cases. The results were as follows: 1. 6cases(37.5%) were under 10 years of age and male to female ratio was 1 to 2.2. 2. Frequency to each symptom ofclassic triads were abdominal pain (62.8%), abdominal mass(43.8%) jaundice(43.8%) in decreased order, and thecalssic triads were present in 2 cases(12.5%) only. 3. 10 cases were type 1 and 6 cases were type IVa according toTodani's classification. 4. Associated findings were stone in 7 cases(43.8%) and pus in 2 cases (12.5%). Ananomalous junction of the pancreaticobiliary ductal system was observed in 1 cases, which is considered to be animportant factor in the development of choledochal cyst. 5. The diagnosis was confirmed in 15 casespreoperatively. mainly with ultrasonography.