The therapeutic effect and the prognosis of transcatheter arterial embolization (TAE) and one-shot chemotherapy were studied in 90 cases of unresectable hepatocellular carcinoma (HCC). A therapeutic effect, which was assessed by the serum concentration of alpha-fetoprotein, angiography, computed tomography and ultrasonography, was seen in 33 (83%) out of 40 cases treated with TAE, and in 16 (32%) out of 50 cases treated with one-shot chemotherapy. In the cases that received TAE, the cumulative percentage survival rates at 6 months, 12 months, and 24 months were 75%, 48% and 20%, respectively. In contrast, the survival rates in the cases that received one-shot chemotherapy were 30%, 10% and 2%, respectively. In addition, the prognosis on the basis of the degree of tumor invasion of the portal vein was studied. In cases with the same degree of tumor invasion, the survival rate of the cases treated with TAE was significantly higher than that of those treated with one-shot chemo-therapy, except for those cases with tumor invasion of the main portal vein. These results show that TAE should be performed as the therapy of first choice in unresectable cases of HCC.