Infection of Hepatitis B Virus (HBV) is a risk factor of chronic active hepatitis (CAH), hepatic cirrhosis and hepatocellular carcinoma (HCC). Infection of HBV may develop to HCC without antecedent hepatic cirrhosis. Pathogenesis of HBV causing malignant changes has not been fully understood. HBx, a protein of HBV, is an activator of transcription process involved in hepatocarcinogenesis. Most of human cancer associated with mutation of p53, a Tumor Suppressor Genes, a protein serves as cellular protection for growth and cell division, which is one of predisposition factor of hepatocarcinoma. Some studies indicate the correlation between mutation/inactivation of p53 and HBV protein x (HBx) in hepatocarcinogenesis. In that process, HBx will suppress p53 function, which will lead to ineffective liver cell division and resulting in HCC.