BACKGROUND Dysfunction of the sphincter of Oddi (SOD) is one of the causes of postcholecystectomy syndrome and biliary pain. Endoscopic sphincterotomy (EST) is recommended in some patients refractory to conservative treatment. This study was designed to evaluate the efficacy of, and complications from EST in patients with SOD. METHODS Between 1990 and 1993, 24 patients clinically diagnosed as having papillary stenosis were treated by endoscopic sphincterotomy. All patients had dilated common bile duct (CBD) in addition to 1) elevation of transaminases and alkaline phosphatase (n = 13); 2) elevation of transaminases and serum amylase (n = 4); 3) normal liver enzymes but delayed biliary emptying on quantitative hepatobiliary scintigraphy (QHS) (n = 7). No CBD stones, organic obstruction or other disorders were found in these patients. RESULTS EST was successfully performed in 24 patients. One patient had minor hemorrhage and one patient developed pancreatitis after EST. Twenty-two of the 24 patients (91.7%) were symptomatically improved before discharge. Twenty-one patients were regularly followed over a median period of 18 months (range 5-36) after EST. Two patients with symptom had recurrence at five and eight month follow up because of restenosis of papilla; another two patients with recurrent biliary symptoms, but the sphincter of Oddi remained wide open. Seventeen of 21 regularly followed patients were symptom free after the median 18-month follow up. CONCLUSIONS EST is an effective and safe modality for treatment of sphincter of Oddi dysfunction.