The sphincter of Oddi (SO) functions to regulate the flow of bile and pancreatic juices as well as to prevent the reflux of duodenal contents into the pancreatobiliary system. When dysfunction of the sphincter occurs, symptoms develop relating to either the biliary or pancreatic portions of the sphincter. The mechanism of this dysfunction remains speculative. SO manometry remains the "gold standard" to correctly diagnose the disorder and stratify therapy. Division of the sphincter is effective for SO stenosis, but there is no proven therapy for SO dyskinesia.