NONE DECLARED Choledochal cyst is a congenital cystic dilation of a part of bile duct that occurs most commonly in the main part of common bile duct. Diagnosis of choledochal cyst is concluded upon disproportionate expansion of extrahepatic bile duct. Symptom trias are: abdominal pain, jaundice and abdominal mass represent clinical guideline signs of diagnosis. Furthermore, hepato-biliary diseases in adults can conceal the primary condition. In addition to this, ultrasound, CT, MRI, cholangiopancreatography (ERCP), transhepatic percutane cholangiography (PTC) guide us for a detailed examination in order to verify the diagnosis. Active endoscopic cholangiography represents an important technique that provides needed anatomic solution and details in diagnosis of choledochal cyst.