A 31-year-old man presented with abdominal pain and iron deficiency anaemia due to gastrointestinal blood loss. Endoscopic retrograde cholangiopancreatography (ERCP) revealed a choledochocele, located between the ampullary sphincter and the sphincters of the common bile duct and pancreatic duct. The choledochocele was removed surgically and appeared to be covered with duodenal mucosa. Gastrointestinal blood loss is explained by the extensive erosions found in the duodenal mucosa of the choledochocele. Choledochoceles should be treated by radical resection.