One hundred twenty-two patients with common bile duct stones and intact gallbladders underwent endoscopic sphincterotomy without cholecystectomy and were followed for 6 months to 9 years (mean 3 years). Nineteen patients died from unrelated causes. One hundred of 103 surviving patients (97 percent) were asymptomatic, whereas 3 had complaints. Acute cholecystitis did not occur in 91 patients without gallstones, whereas it did occur in 5 of 31 patients (16 percent) with gallstones (25 patients) or nonvisualization of the gallbladder (6 patients). Two patients in the former subgroup had formation of new gallstones. We conclude that cholecystectomy should be advocated whenever possible in patients with gallstones or nonvisualization of the gallbladder after endoscopic sphincterotomy due to the high incidence of acute cholecystitis in this subgroup and that operation is not necessary in patients without gallstones; however, one should be aware of possible formation of new stones in the gallbladder.