Length of biliary (CBD) and/or pancreatic (PD) sphincter of Oddi (SO) was measured during perendoscopic or intraoperative manometry in 21 control subjects and in 46 patients with biliary disease. When the high resting pressure (HPZ) and the phasic wave zone (PAZ) were considered, SO length was, in the control group, 9.5 +/- 0.5 mm (M +/- SE) and 9.4 +/- 0.6 mm at the level of the CBD-SO, and 7.7 +/- 0.6 mm and 6.9 +/- 0.5 mm at the level of the PD-SO. The physiological sphincter length appeared substantially shorter than the anatomical one, as reported in the literature. No significant differences were found between controls and patients with CBD stones. Endoscopic sphincterotomy without manometry reduced mean sphincter length length of the sphincterotomy was tailored to the manometric findings. Surgical partial sphincterotomy reduced sphincter length by only 46.7 +/- 10.3%.