Familial cases of the various types of intestinal atresia are well described, and we now report an additional family. Based on a review of the literature, a classification system for the different types of familial atresia is presented. Current teaching attributes most jejunoileal atresias to in utero vascular accidents occurring relatively late in gestation (after the 11th or 12th week). Although some cases clearly occur this way, as a result of processes such as volvulus and intussusception, knowledge of the familial form of the disease indicates that most cases of jejunoileal atresia actually result from disruption of a normal embryologic pathway, most likely the development of the superior mesenteric artery and its branches. They should be considered to be true embryologic malformations rather than acquired lesions.