Serum RASSF1A methylation occurred significantly more frequently in patients with HCC (122/190, 64.2 %) than in patients with LC (20/114, 17.5 %), patients with CHB (6/120, 5.0 %) and in healthy individuals (0/160, 0) (P < 0.001); moreover, it allowed for the discrimination of patients with HCC from those with CHB with an areas under the ROC curves (AUC) of 0.796 (64.2 % sensitivity and 89.8 % specificity). The gene discussed is RASSF1; the disease is hepatocellular carcinoma.