Recent developments of manometric and endoscopic instrumentation have rekindled interest in sphincter of Oddi function. As a result of human and animal studies, our understanding of normal sphincter of Oddi physiology has increased and possible motility abnormalities are being identified. Manometric studies have shown that the sphincter of Oddi is characterized by prominent phasic contractions which are super-imposed on a low tonic pressure. The phasic contractions are orientated mainly in an antegrade direction; however, both simultaneous and retrograde contractions are registered. Cineradiography has demonstrated that the phasic contractions have a propulsive function, expelling small volumes of fluid from the common bile duct into the duodenum. Intravenously administered cholecystokinin-octapeptide normally inhibits the phasic contractions and reduces the sphincter tone. Motility abnormalities may occur if the sphincter of Oddi exhibits abnormally high tone, alteration in the direction of the phasic contractions, abnormal changes in the contraction frequency, or abnormal responses to hormonal stimulation. Preliminary human studies demonstrate disorders in sphincter of Oddi motility patterns, suggesting that motility abnormalities may be associated with choledocholithiasis, dyskinesia and idiopathic relapsing pancreatitis.