The results of selective intraarterial vasopressin-infusion therapy and embolization therapy were compared in two groups of patients with major gastrointestinal hemorrhage. The site of bleeding, clinical course, complications, and transfusion requirements were evaluated in each group. Intraarterial vasopressin infusion therapy resulted in successful control of hemorrhage in 16 (70%) of 23 patients. Four patients, however, rebled and an operation was necessary, reducing the overall success rate to 52% (12 of 23). In the group treated with embolization therapy, primary success was achieved in 17 (71%) of 24 patients. Four patients in whom initial embolization failed to control bleeding underwent repeat embolization and in all four permanent control of hemorrhage was obtained, producing an overall success rate of 21 (88%) of 24. Analysis of our results according to site of hemorrhage suggests that at certain sites embolization is a preferred method of treatment; embolization allows earlier control of gastrointestinal hemorrhage and a reduction in transfusion requirements.