In treating cancerous metastases to the liver, we combined hyperthermic treatment with chemotherapy via the intra-hepato-arterial injection (IHAI) of cis-diamminedichloroplatinum (II) plus 5-fluorouracil. The subjects were 14 patients having metastases to the liver: 3 from gastric cancer and 11 from colorectal cancer. In metastases of colorectal origin, the response rate (partial response) was 55%; the 1-year survival rate was 80%; the 50%-survival period was 23 months. The response rate and the 50%-survival period in metastases of gastric origin were 67% and 11 months, respectively. When IHAI chemotherapy was combined with hyperthermic treatment, antitumor effects were generated in 3 of 6 metastatic patients from colorectal cancer, who had received no benefit from the IHAI chemotherapy alone. Better results were produced by thermochemotherapy than by IHAI chemotherapy alone. Hepatic blood flow, which influences the antitumor effect of hyperthermic treatment or chemotherapy, was measured using the 133Xe clearance method. Over the long term, the hepatic blood flow, especially that of the portal-venous route, showed a decreasing tendency after repeated sessions of the present regimen. This fact suggests the increased retainability of arterial-injected carcinostatics in cancerous tissues.