Endoscopic manometry was performed to evaluate the motor activity of the sphincter of Oddi (OS) in six patients with Lemmel's syndrome, four of whom had acute cholangitis and two of whom had acute pancreatitis. As controls, 24 patients undergoing cholecystectomy without juxtapapillary duodenal diverticula (JPD) for cholelithiasis or cholesterol polyps in the gallbladder were also studied. The OS basal pressure and contraction pressure values were 12.4 +/- 5.1 mmHg and 103.4 +/- 24.3 mmHg, respectively, in the patients with Lemmel's syndrome, and 19.5 +/- 5.1 mmHg and 136.8 +/- 28.2 mmHg, respectively, in the control patients. These differences between the groups were statistically significant; however, the wave frequency was not significantly different between the groups. The mean percentages of antegrade, simultaneous, and retrograde sequences were 37.5% +/- 11.3%, 19.9% +/- 8.7%, and 43.4% +/- 11.7%, respectively, in the patients with Lemmel's syndrome, and 66.5% +/- 11.0%, 20.2% +/- 4.7%, and 14.3% +/- 9.2%, respectively, in the controls. The differences between the groups were significant (P < 0.01) for the antegrade and retrograde sequences. These findings indicate that dysfunction of the OS in patients with Lemmel's syndrome could be important in the development of hepatocholangiopancreatic disease caused by duodenobiliary and duodenopancreatic reflux.