Gastrointestinal bleeding in infants and children can be quite alarming and anxiety-provoking for parents and caregivers alike. In most cases the cause is benign, and the course self-limited. However, in the patient with significant bleeding, an aggressive diagnostic approach is warranted. The differential diagnosis can be extensive and varies depending on the age of the patient. Meckel's diverticula and intestinal duplications may cause gastrointestinal bleeding in almost any age group and require a high index of suspicion for diagnosis. Bleeding usually is painless but may be massive. The advent of technetium (Tc) 99m pertechnetate radionuclide scanning has greatly facilitated the diagnosis of Meckel's diverticula and may also be useful for intestinal duplications. A positive scan requires the presence of ectopic gastric mucosa, which may be identified in both Meckel's diverticula and intestinal duplications. The significance of ectopic gastric mucosa is that it contains acid-secreting parietal cells, which may cause ulceration and bleeding. Only rarely are intestinal duplications diagnosed preoperatively. After initial fluid resuscitation, bleeding from Meckel's diverticula and intestinal duplications require surgical intervention. Resection is the treatment of choice. Diverticulectomy or segmental bowel resection including the diverticulum should be performed for bleeding Meckel's diverticula. It is important to remove the ectopic mucosa and site of ulceration to prevent rebleeding episodes. Intestinal duplications share a common wall and blood supply with native bowel. Segmental resection is indicated if it can be performed without sacrificing a significant portion of bowel. A recent advance has been laparoscopic-assisted resection of Meckel's diverticula and intestinal duplication cysts. With the aid of the laparoscope, extracorporeal or intracorporeal resection may be performed.