The aim of this study is to elucidate the prognostic factors and the treatment effect on survival in hepatocellular carcinoma (HCC) patients with Child C cirrhosis. Out of 3330 newly discovered HCC patients, 157 consecutive HCC individuals with Child C cirrhosis were enrolled. The prognostic factors were examined by Cox proportional hazards regression analysis and their survival was compared by propensity score-matched analysis. Multivariate analysis revealed that high serum bilirubin (>3 mg dl(-1)), the presence of uncontrollable ascites, and a high platelet count (>8 x 10(4) mm(-3)), so-called background liver factors, as well as multiple tumours, large tumours (>3 cm), high alpha-fetoprotein (>400 ng ml(-1)), and the presence of portal vein thrombus, so-called tumour factors, were factors of poor prognosis. While transcatheter arterial chemoembolisation (TACE) was a factor of good prognosis (relative risk=0.50, 95%CI=0.27-0.89, P=0.019), local ablation therapy and transcatheter arterial chemoinfusion (TAI) were not significant prognostic factors. The survival of patients who received TACE was superior to matched patients without active treatment (P=0.009); however, we did not observe survival benefit after local ablation therapy or TAI. These results suggested that tumour factors as well as background liver factors are prognostic factors of HCC even in patients with Child C cirrhosis, and selective use of TACE in these patients provides survival benefit.