Hepatitis B virus (HBV) infection during childhood can cause acute, fulminant or chronic hepatitis, liver cirrhosis, and liver cancer. Approximately 90% of the infants of hepatitis B e antigen (HBeAg) seropositive mothers become hepatitis B surface antigen (HBsAg) carriers. Children chronically infected are mostly asymptomatic. Although liver damage is usually mild during childhood, severe liver disease, including cirrhosis and hepatocellular carcinoma, may develop insidiously for 2–7 years. Spontaneous HBeAg seroconversion occurs gradually as the age of the child increases. Viral replication is reduced during this process, which is usually preceded by an elevation of aminotransferases. In a long-term follow-up study, the annual HBeAg seroconversion rate was 4–5% in children older than 3 years of age and less than 2% in children under 3 years. The annual seroconversion rate of HBsAg was very low (0.56%). Age at infection, maternal HBsAg and HBeAg status, host immune status, and possibly the HBV strain are the main factors determining the course of HBV infection in children.