Eleven patients with retroperitoneal perforation complicating endoscopic management of bile duct obstruction were seen over a seven-year period. In nine patients endoscopic sphincterotomy or pre-cut papillotomy had been performed, but in two who had not undergone sphincterotomy perforation occurred because of the penetration of a guidewire during attempts to negotiate a malignant bile duct stricture. Eight out of eleven patients remained asymptomatic, and all recovered with conservative management. Asymptomatic retroperitoneal perforation can complicate therapeutic ERCP even when sphincterotomy is not performed, but conservative management is usually effective if the complications is recognized immediately.