The serum markers of hepatitis B virus (HBV) infection are complex, mainly including HBV surface antigen (HBsAg) and antibody to HBsAg, HBV e antigen (HBeAg) and antibody to HBeAg, antibody to HBV core antigen. The natural history of chronic HBV infection is complex and variable and greatly influenced by the age of infection, the level of HBV replication, HBV genotype and mutations, presence of HBeAg, ALT level, coinfection with HCV and/or HDV, host immune status. Four stages of chronic HBV infection are the immune tolerant phase, the immune clearance phase, the low or non-replicative phase, and the reactivation phase. Some patients with HBeAg positive, high level of ALT and HBV DNA>105 copies/mL would develop liver-related complications, such as cirrhosis, hepatocellular carcinoma and liver failure. Available evidences indicate that control of HBV replication with antiviral drugs can decrease the incidence of these complications and mortality.