Mucinous ductal ectasia is an uncommon disorder, characterized by ductal dilatation and filling with thick, viscid mucus, described in the pancreas. We report a case of mucinous ductal ectasia of the biliary tree. The cause of the mucus production was mucous metaplasia in the biliary epithelium. The patient was followed for 16 years, treated with serial saline flushings of the biliary tree whenever he became symptomatic.