Based on a case report, we describe choledochal cysts in adults. Choledochal cysts are rare, and are often overlooked. The aetiology is unknown. The symptoms are pain or discomfort, episodes of jaundice, cholangitis and pancreatitis. Increased liver function tests and gallstone disease are common. There is an increased risk of malignant tumours in the cysts and adjacent organs. Ultrasonography, computer tomography, endoscopic retrograde cholangiopancreaticography, percutaneous cholangiography and magnetic resonance imaging with magnetic resonance cholangiopancreaticography are relevant diagnostic tools. Extrahepatic cysts should be operated with radical excision, with Roux-Y hepaticojejunostomy or other reconstructions allowing later diagnostic and therapeutic access to the bile ducts. Long term results are good.