We analyzed the clinical characteristics and survival of 185 patients with hepatitis B virus-related hepatocellular carcinoma (HBV group) and 1033 with hepatitis C virus-related hepatocellular carcinoma (HCV group) by multi center study. The patients in the HBV group (mean age 52.1 yr) were about 10 years younger than those in the HCV group (mean age 62.9 yr). Liver function, as measured by indocyanine green retention at 15 min, was better in the HBV group (17.5%) than in the HCV group (25.4%). A higher proportion of the HBV group (55%) than the HCV group (44%) had clinical stage I, T-factor differed significantly between the groups: 53% of the HBV group were T3-4 compared with 41% of the HCV group. Furthermore, a higher proportion of the HBV group were graded 2-3 for tumor thrombus in the portal vein (20.3%) and had poorly differentiated hepatocellular carcinoma (7%) compared with the HCV group (7.1% and 5% respectively). Univariate analysis identified poor prognostic factors for hepatocellular carcinoma as HBV, age < or = 50 yr, clinical stage II-III, a high AFP level, higher number of tumors, larger tumor size, tumor thrombus in the portal vein 2-3 and in the hepatic vein 2-3. On multivariate analysis, poor prognostic factors were a high AFP level, higher number of tumors, tumor thrombus in the portal vein 2-3 and in the hepatic vein 2-3, but not HBV, age, clinical stage or tumor size. These results suggest that HBV itself is not a stronger prognostic factor than HCV.