Gastrointestinal (GI) bleeding is an alarming problem in children. Although many causes of GI bleeding are common to children and adults, the frequency of specific causes differs greatly, and some lesions, such as necrotizing enterocolitis or allergic colitis, are unique to children. This article reviews the spectrum of GI bleeding in infants and children. The causes, diagnostic evaluation, and management are discussed, and differences with adult medicine are highlighted.