The pathogenesis of intestinal atresia has shown well that mesenteric vascular insults during an intrauterine life played an important role, and it has been shown in animal experiments. Intrauterine intussusception was suggested as one of the etiologies that cause jejunoileal atresia. The aims of this study were ⓛto see if polypoid lesions in congenital ileal atresia were associated with intrauterine intussusception and ②to make diagnostic criteria for possible intrauterine intussusception. Intraluminal polypoid lesions were found in three patients, with congenital ileal atresia. They were Louw classification type I in two patients, and type II in one patient. Two lesions were composed of intestinal wall layers contiguous with adjacent small bowels, however, atrophic non-viable tubular structure was found in one patient. All of this signifies that they were a remnant of an intrauterine intussusception which had occurred in a different developmental stage. In conclusion, intraluminal polypoid lesion in ileal atresia was suggested to be the remnant structure of intrauterine intussusception. Such instances were highly suggested by the followings: ⓛ type I or II in Louw classification ② intraluminal polypoid lesion adjacent to atretic portion, ③ identifiable intestinal wall layers in histologic examination, ④ positive occult blood in meconium.