The paper reports on a case of congenital cystic dilatation of the main bile duct in a female patient, 3 years old, with a clinical evolution of the disease from 2 years old. The anamnestic data corroborated with iv cholangiography and hepatobile echography specifies the clinical diagnosis that was intraoperatively confirmed. The case was solved by resection of the cystic bag, followed by hepatojejunostomy on the loop ablated "en Y" à la Roux.