To examine the association between socio-economic status (SES) and liver cancer mortality among Korean men. Prospective cohort study Data were acquired from a large, prospective cohort study that included 548,530 civil service workers aged 30-59 years who had undergone health examination in 1998 provided by the Korean National Health Insurance System. Information on lifestyle and demographic characteristics was acquired through self-administered questionnaires. The main outcome event was mortality from liver cancer. Cox proportional hazards model was used to estimate relative risks (RRs) and 95% confidence intervals (95% CIs) after adjusting for age, body mass index, fasting serum glucose, alcohol consumption, smoking and hepatitis B surface antigen (HBsAg) status. Liver cancer mortality differentials relating to SES were statistically significant and consistent in the fully adjusted model. Compared with the highest SES category, excess risk associated with liver cancer mortality was observed with decreasing SES levels: the RRs in the upper middle, lower middle and low SES categories were 1.35 (95% CI 1.13-1.61), 1.54 (95% CI 1.28-1.86) and 1.72 (95% CI 1.45-2.04), respectively. There was no effect modification by HBsAg status on the association between SES and liver cancer mortality. This study demonstrated an inverse association between SES and liver cancer mortality, suggesting that SES is an independent predictor of liver cancer mortality. The policies and interventions regarding prevention of liver cancer need to focus on disadvantaged groups in order to reduce health disparities related to liver cancer.