Biliary cystadenoma is a rare cystic tumour of the liver that can be difficult to differentiate from other types of benign hepatic cysts. We report the case of a 32-year-old woman who presented with obstructive jaundice due to a large cystic lesion of the left hepatic lobe. Resection of the mass revealed a mucinous cystadenoma with protrusion of a pedunculated extension into the left hepatic duct and the common bile duct. We describe the clinical features, the radiological findings, the surgical management and the pathology of this rare entity.