This article reports on a new approach to hepatic arterial chemoembolization therapy using ethiodized oil (Lipiodol, Ultra Fluide), cisplatin, and gelatin sponge (Gelfoam, Upjohn, Kalamazoo, MI) for hepatocellular carcinoma (HCC). The anticancer effects of this therapy on 20 patients who underwent subsequent hepatic resection were evaluated mainly by histologic examination. All main tumors were reduced in size following this therapy. It is notable that in 65% of the patients the tumor size was reduced to less than 50% of that before therapy. All the values of serum alpha-fetoprotein (AFP) in the patients who exhibited pretreatment levels exceeding 100 ng/ml dropped by more than 50%, and in 55% of them it fell below 20 ng/ml. The concentration of platinum in the tumor tissue was significantly higher than that in the nontumorous tissue. In 15 of 20 patients (75%), the main nodules were completely necrotic. Thirteen of the patients had daughter nodules and/or small intrahepatic metastases (Group A); nine had tumor emboli in the portal (hepatic) vein (Group B); 17 had intracapsular invasions (Group C); and ten had extracapsular invasions (Group D). The ratios of patients with completely necrotic cancer cells in Group A were nine of 13 (69%); in Group B, seven of nine (78%), in Group C, 11/17 (65%); and in Group D, four of 10 (40%). In eight of the 20 patients (40%) no viable cancer cells were recognized at any foci. Lesions other than those with extracapsular invasion could be considerably eliminated with this form of therapy. It is expected that this method will become the therapy of choice not only for palliative treatment but also for preoperative treatment.