One of the more uncommon causes of acute intestinal obstruction is impaction of a gallstone in the intestinal lumen. Almost without exception, this is the result of a spontaneous internal biliary fistula, occurring most frequently between the gallbladder and the duodenum. A gallstone ileus, in the absence of a previous communication between intestine and biliary tree, is, however, a rare occurrence; only two such cases have been discovered in the literature. The site of formation of the stone in one of these cases was a duodenal diverticulum1 and in the other a blind duodenal stump following subtotal gastrectomy.2 It is the purpose of this report to review briefly the problem of gallstone obstruction of the intestinal tract and to present a third case of acute intestinal obstruction resulting from impaction of a large gallstone in the terminal ileum in the absence of a previous biliary-tract fistula. Incidence In