Associations between ABO blood groups and risk of several malignancies have been reported, although there are limited data regarding hepatocellular carcinoma (HCC). The aim of this study was to investigate any possible association between the ABO genotype, especially blood group A, and HCC risk in Koreans.We conducted a case-control study of 1,538 patients with newly diagnosed HCC at Chonnam National University Hwasun Hospital and 1,305 randomly selected members of the general population. The ABO genotype was determined by multicolor real-time polymerase chain reaction (PCR) using displacing probes. Adjusted odds ratios (aORs) and their 95% confidence intervals (CIs) were calculated using logistic regression models with adjustment for gender, age, smoking, alcohol drinking, and hepatitis B and C status.The risk of HCC in genotype AA was significantly higher than in OO (aOR=1.773, 95% CI=1.161-2.705). The risk in blood group A was also higher than in blood group O (aOR=1.448, 95% CI=1.005 1.897). No significant difference was found for the AA, BO, BB, and AB genotypes, or blood group B and AB.Blood group A and genotype AA showed the highest risks of HCC in a Korean population. No significant difference was found for the AO, BO, BB, and AB genotypes, or blood group B and AB.