A cursory review of the literature on acute pancreatitis is sufficient to impress on one that there is a striking lack of agreement among investigators concerning the question of etiology. That this is true, in respect to many possible factors, is not to be wondered at in view of the difficulties encountered on investigation. However, when the question at issue is one of gross anatomy, it does seem incredible that there should be a marked disagreement. Nevertheless, such is the case, as will be shown presently. Through the pioneer work of Opie1and many subsequent investigators, sufficient reliable evidence has been accumulated to warrant one in suspecting that a reflux of infected bile up the pancreatic duct or a conversion of the biliary and pancreatic ducts into a common and freely communicating system, in the presence of infected bile, may lead to acute pancreatitis. As a matter of fact,