Background: Little is known about the long-term effects of endoscopic biliary sphincterotomy. Methods: We retrospectively evaluated the rate of late complications after endoscopic sphincterotomy (EST) for bile duct stones. Patients had to meet the following inclusion criteria: (1) treated between 1976 and 1980, (2) complete stone removal after EST, (3) prior cholecystectomy or elective cholecystectomy within 2 months after EST, and (4) 60 years old or younger at the time of ERCP. A total of 100 patients were identified. Information was obtained from general practitioners and patients by telephone. Patients completed a postal questionnaire and a blood sample was obtained for liver function tests. Results: Information was obtained for 94 patients (in the majority of cases [87%] from multiple sources). There were 26 men and 68 women with a mean age of 51 years at the time of ERCP (range, 23 to 60 years). Early complications (<30 days) occurred in 14 patients (15%). One patient died of a retroperitoneal perforation secondary to EST. During a median period of 15 years (range, 3 to 18 years), 22 patients (24%) developed a total of 36 late complications. There were 21 patients with symptoms of recurrent bile duct stones and one patient with biliary pancreatitis. Other late complications, such as recurrent ascending cholangitis or malignant degeneration, were not observed. An ERCP was performed in 20 of the 22 patients with late complications and demonstrated bile duct stones in 13, combined with stenosis of the EST opening in 9 patients. Late complications were initially managed endoscopically and/or conservatively. One patient underwent surgery after failed endoscopic treatment and one patient died of cholangitis before she could undergo an ERCP. Twelve other patients died of unrelated causes during follow-up. Conclusions: After EST for bile duct stones, late complications occur in a significant proportion of patients. Stone recurrence remains the most important problem, but can in general be managed endoscopically. (Gastrointest Endosc 1996;44:643-9.)