Choledocus cyst is a rare anomaly which affects the intramural segment of the common bile duct. The presenting clinical symptoms are recurrent abdominal pain, episodes of jaundice, with fever, and increased levels of serum amylase. Although the diagnosis may be obtained by conventional clinical and radiologic methods, the anatomy of the ducts is best demonstrated by endoscopic retrograde cholangiopancreatography; moreover, this technique enables some therapeutic manoeuvres. We present a young girl with a choledocus cyst and some other ductal abnormalities with the results of the previously mentioned technique.