简介：AbstractCholedochal cysts is a rare congenital cystic dilatation of common biliary duct. The most common prenatal diagnosed form type- I (85%-90%), consists of fusiform dilation of the common bile duct. There is communication between the bile duct and the cyst. In antenatal period diagnosis may be made by the presence of a cyst in the upper right side of the fetal abdomen on ultrasound. To differentiate it with other cystic lesions prenatal ultrasonography (USG), three-dimensional USG and magnetic resonance imaging may be helpful. By early diagnosis and prompt removal of cyst in postnatal period long term complications like development of biliary cirrhosis, portal hypertension, calculi formation or adenocarcinoma can be avoided in later life. The operative mortality is about 10%. We are reporting a case of antenatal diagnosis type I congenital choledochal cysts at 21 weeks, its follow up and successful postnatal management.