From a consecutive series of 451 patients with post-cholecystectomy symptoms referred for endoscopic retrograde cholangiopancreatography (ERCP), 40 (9 per cent) were diagnosed as having sphincter of Oddi dysfunction. Eight patients were excluded from the study because of incomplete data (n = 6) or additional diagnoses (n = 2). Thirty of the patients had successful ERCP and endoscopic sphincterotomy (ES); this failed in the remaining two because of severe papillary stenosis (6.3 per cent). Endoscopic biliary manometry was performed in 23 patients (77 per cent). Immediate post-ES complications occurred in eight patients (25 per cent). At a median follow-up of 46 months (range 10-88 months) 19 patients had a good outcome (63.3 per cent) and 11 patients had a poor outcome (36.7 per cent). Patients with a good outcome tended to have a delay of months or years following cholecystectomy before the development of symptoms (median 6 years versus 0 years, P = 0.0003). At ERCP, patients with a good outcome had greater common bile duct diameters (mean +/- s.d. mm, 12.6 +/- 3.6 versus 8.8 +/- 1.8, P = 0.0003) and delayed drainage from the biliary tree of injected contrast (13 versus 2 patients, P = 0.02). Endoscopic biliary manometry was abnormal in all 15 patients with a good outcome in whom it was performed but in only 3 out of 8 patients with a poor outcome (P = 0.003). Sphincter of Oddi dysfunction is an important, albeit uncommon, cause of post-cholecystectomy symptoms. ES provides symptomatic relief in the majority of patients but improved criteria for predicting outcome are required.