We performed intra-arterial infusion hyperthermochemotherapy by retaining an intra-arterial reservoir in 17 lesions of 12 patients with non-resectable, metastatic or recurrent gastric cancers. The 12 patients consisted of one with a primary gastric cancer lesion, 6 with a solitary gastric cancer lesion metastasizing to the liver, 4 with gastric cancer accompanied by hepatic metastasis, lymph node metastasis or local recurrence, and one with a gastric cancer lesion metastasizing to Douglas' pouch. A catheter was retained in the hepatic artery of all 6 patients with a solitary gastric cancer lesion metastasizing to the liver, and a catheter was retained in the aorta of the patient with a primary lesion, 3 of the 4 patients with two or more metastatic lesions, and the patient with a lesion metastasizing to Douglas' pouch. The duration of each hyperthermia session was 50 minutes, and one or two sessions were performed within a week. One course consisting of 5 or 6 sessions was repeated. Antineoplastic drugs such as MMC, 5-FU, ADR, epi-ADR, CDDP and VP-16 were injected in bolus form or administered serially through the reservoir. Nine of the 12 patients had polypharmacy. One to 3 courses or 4 to 20 sessions at maximum (average 9.8 sessions) were given. The rate of efficacy of intra-arterial infusion hyperthermochemotherapy was 44% for hepatic metastasis and 25% for lymph node metastasis. The local recurrent lesions, the lesion metastasizing to Douglas' pouch and the primary lesion did not respond to therapy.