A 69-year-old female with unresectable hepatocellular carcinoma was treated with continuous arterial infusion of low-dose cisplatin (10 mg/body/day) and 5-fluorouracil (250 mg/body/day). The regimen was continued for 5 days then discontinued for 2 days, and repeated for 4 weeks. The portal tumor thrombus almost disappeared and HCC was smaller than before chemotherapy. Tumor marker (AFP and PIVKA-II) decreased remarkably. As tumor markers increased again 2 months later, the same regimen chemotherapy was performed once more. The patient was treated with arterial chemotherapy as an outpatient. The present case of hepatocellular carcinoma with portal tumor thrombus was effectively treated by arterial infusion chemotherapy with low dose cisplatin and 5-fluorouracil.