Congenital duodenal diaphragms in the adult are uncommon, unsuspected lesions that infrequently cause intestinal obstruction. The diaphragms may be single or multiple and are usually located near the ampulla of Vater. Three cases are summarized and the recent literature reviewed. At least 35 cases have been reported. Treatment most often consisted of duodenotomy, excision of the web and duodenal closure.