Enterokinase is a glycoprotein and is now designated enteropeptidase (E.C.3.4.4.8.). It is present in the duodenal and jejunal mucosa. Pancreatic proteolytic enzymes are secreted as proenzymes. Enterokinase converts trypsinogen to trypsin in the duodenal lumen. Duodenopancreatic reflux of duodenal enterokinase may be important in the pathogenesis of experimental and clinical acute pancreatitis. Congenital enterokinase deficiency is a distinct clinical entity characterized by diarrhea, failure to thrive, hypoproteinemia, and edema. Acquired enterokinase deficiency may occur in some diffuse small bowel diseases. Steatorrhea of celiac spruce may be due partly to the fact that deficiency of secretin and cholecystokinin may interfere with the action of enterokinase. The interrelationship between secretin, cholecystokinin, enterokinase, and bile salts is not completely understood.