During the evaluation of patients with profuse gastrointestinal bleeding, it is often difficult to accurately localize bleeding sites in the small intestine. Moreover, during laparotomy, there may be no intraoperative findings to allow identification and resection of the bleeding lesion. Here the authors report a case of severe intestinal bleeding in an infant in whom the intraoperative injection of methylene blue dye into a terminal branch of the superior mesenteric artery was critical in determining the exact location of bleeding. After accurate localization of the bleeding source and segmental intestinal resection, the child recovered uneventfully with no recurrence of gastrointestinal bleeding. To the authors' knowledge, this is the first reported use of this technique in infancy.