From a total of 23 cases from five hospitals, acute colonic mucosal necrosis developed in three patients following transcatheter embolotherapy for colonic hemorrhage. Although embolic therapy for lower gastrointestinal bleeding is associated with appreciable risk, these risks are less than those of emergency operation for hemorrhage. The alternative transcatheter therapeutic modality, vasopressin infusion, is often associated with continued or recurrent hemorrhage, is relatively contraindicated in patients with coronary disease, and produces numerous complications. Transcatheter embolotherapy is recommended for patients with colonic bleeding who have a contraindication to vasopressin administration, who are refractory to vasopressin, or who rebleed following treatment with vasopressin.