BACKGROUND Endoscopic manometry is considered useful to identify dysfunction of the sphincter of Oddi (SO) and to predict in which patients good results can be expected after endoscopic sphincterotomy, but this has not been definitively demonstrated. METHODS Endoscopic manometry of the SO was used in a group of 30 patients with benign papillary stenosis (BPS), in comparison with 30 control subjects. During endoscopic manometry an intravenous bolus of cholecystokinin octapeptide was given to 12 patients and to 10 controls. In 24 BPS patients endoscopic sphincterotomy was performed. RESULTS No significant differences were observed between controls and patients with regard to median values of SO basal (20 and 21.5 mmHg) and peak pressure (123 and 126 mmHg), wave amplitude (100 mmHg), frequency (4 waves/min), and propagation of the common bile duct/duodenum gradient (12.5 and 12.1 mmHg). In two BPS patients a paradoxic response to CCK-OP was observed. Endoscopic sphincterotomy, performed in 24 BPS patients (17 with SO basal pressure less than 40 mmHg and 7 with more than 40 mmHg), gave good results in 23, without any complication. No differences were observed in the results of the endoscopic sphincterotomy among patients with basal pressure more than 40 mmHg and those with less than 40 mmHg. CONCLUSIONS On the basis of this study, manometric data do not seem helpful for diagnosis of BPS or to discriminate which patients can be treated with endoscopic sphincterotomy.