Gastrointestinal (GI) bleeding is a relatively infrequent complication seen in patients with AIDS. As with non-HIV-infected individuals, upper GI bleeding is much more common than lower GI bleeding. In patients with AIDS, upper GI bleeding can result from etiologies related to underlying HIV infection [cytomegalovirus (CMV), Kaposi's sarcoma, idiopathic esophageal ulcers, etc] or be unrelated to HIV infection (peptic ulcer, portal hypertension, Mallory-Weiss tear, etc.). Lower GI bleeding is caused predominantly by etiologies related to underlying HIV disease; CMV colitis is the most common cause. In contrast to non-HIV-infected individuals, hemorrhoids and anal fissures can result in significant bleeding in AIDS patients because of associated thrombocytopenia. Management of GI bleeding in AIDS patients is similar to patients without HIV infection, and includes resuscitation, identification of the bleeding source, achieving hemostasis, and preventing recurrent bleeding. Several etiologies that cause GI bleeding in patients with AIDS can be diagnosed through endoscopy, either by their characteristic endoscopic appearance or mucosal biopsies.