Ten patients with relapsed and hormone-resistant prostate cancer were given intra-arterial infusion with, mainly, cisplatin using the reservoir system. The tip of the indwelling infusion catheter was inserted from the femoral artery into the internal iliac artery or common iliac artery. The opposite end of the infusion catheter was connected to a reservoir implanted subcutaneously at the thigh portion. Combination chemotherapy using methotrexate, adriamycin and cisplatin (MAC therapy) was mainly performed. According to criteria of the Jpn. Assoc. for Cancer Ther., the response rate was 23%, including 3 or PR cases. Regarding the survival rate, the 1-year survival rate was 66.7% and the 2-year rate was 33.3%. Concerning adverse reactions, nausea, vomiting and anorexia were noted in all cases. Stomatitis, leukopenia and thrombocytopenia were also found in 38%. We consider that the IA-MAC therapy is one of the most useful regimen for the treatment of the relapsed and/or hormone-resistant prostate cancer.