Intraluminal pressure recordings from the sphincter of Oddi (SO) have made significant contributions towards the understanding of normal SO function and are being used for the diagnosis of SO motility abnormalities. In this study the endoscopic intraluminal methods for measuring SO pressure changes have been adapted for use under sterile conditions during surgery on the biliary system. Sphincter of Oddi pressure measurement in a group of patients undergoing elective cholecystectomy for gallstones, were compared with a group of control subjects undergoing endoscopic study of the SO. There was no significant difference in CBD pressure. SO basal pressure, SO wave amplitude and SO wave frequency. However, a highly significant difference was noted in the propagation direction of the SO contractions. The control subjects had a predominance of antegrade contractions whereas patients undergoing cholecystectomy had a predominance of retrograde contractions. This result suggests an association between SO motility disorder and the presence of gallstones.