It has been more than 100 years since Rugero Oddi described the sphincter that bears his name. In that time, investigators have determined its precise anatomy and they have demonstrated its independence from the duodenal muscle wall. Modern manometric techniques have defined the motor activity of the sphincter and motility abnormalities in patients presenting with either recurrent biliary-type pain or idiopathic recurrent pancreatitis. The term Sphincter of Oddi dysfunction is used to describe motility disorders of the sphincter. Clinical studies have shown that in patients with manometrically determined stenosis, division of the sphincter is associated with cure of the symptoms in more than 70%. For patients with biliary-type pain, division of the bile duct sphincter is all that is required, whereas in patients with idiopathic recurrent pancreatitis, division of the septum between the bile duct and the pancreatic duct is mandatory.