Hepatitis B viruses can cause chronic liver diseases in both children and adults. In hyperendemic areas, although most related complications occur during adulthood, nearly half of the primary infection in chronic hepatitis B virus carriers occurs in perinatal period through maternal transmission and the other half are from horizontal transmission mainly through intrafamilial spread or injection using unsterilized needles. Children with chronic hepatitis B virus infection are mostly asymptomatic. They are generally active and growing well with very rare exceptions. Even with acute exacerbation of liver function and active inflammation, jaundice or growth failure is uncommon. Mild histologic abnormalities in the liver begins early in life and may progress to severe liver impairment in later life. Severe liver damage, with bridging hepatic necrosis or fibrosis, or cirrhosis of the liver may occur, but is rare during childhood. Universal immunization program of hepatitis B virus has been proved to be effective in reducing hepatitis B carrier rate for more than 10 folds, and the incidence of hepatocellular carcinoma in children has also been reduced significantly.