Perfusion techniques in the treatment of patients with cancer consist in circulating solutions of anticancer drugs through the blood vessels. If the neoplasm is limited to a part that can be isolated, regional perfusion is used; if this is not possible, marrow is first removed from the sternum and iliac crests, total-body perfusion is carried out, and the marrow is reinjected intravenously after the perfusion has been completed. Perfusion methods were used in 145 patients with cancers, 72 of which were carcinomas. There were 56 perfusions of the lower extremity. Perfusion made it possible to attain, in the tumor-bearing area, 15 to 20 times the concentrations obtainable by systemic administration. No specificity of an agent for a given tumor was found, and none of the agents tried was curative. The complications of the treatment in most instances were not serious, but there were eight operative deaths. The best results were obtained in patients with malignant melanoma.