Introduction: Prophylactic cholecystectomy (PC) is advised after ES and clearance of ductal calculi on the basis of a randomized controlled trial that showed a requirement for cholecystectomy in 36% of patients who defer surgery. Other studies suggest the cholecystectomy rate to be as low as 8%. Methods: To determine the proportion of patients who deferred cholecystectomy and the outcome, we reviewed 870 consecutive patients who underwent endoscopic retrograde cholangiography and sphincterotomy; the gallbladder of 420 of these remained in situ. Patients were assigned to PC or deferred cholecystectomy (DC) groups. Results: Cholecystectomy was deferred in 180 of 310 eligible patients. DC patients were significantly older (66.4 v. 49.8 yr) and sicker (according to the American Society of Anesthesiology [ASA] physiological status score) and had a significantly higher mortality rate than did PC patients. Deaths were principally cardiovascular and not biliary related. After a follow-up of 24.2 (