The immunogenic response of healthy Chinese children to three different doses of hepatitis B virus (HBV) vaccine was compared. One hundred susceptible children received two doses of 10, 20 or 40 micrograms a month apart. A month following the first dose 33% of all the children had antibodies. The response rate rose to 78% a month later and 99% four months later. Ninety percent of the 100 children still had antibody at 12 months after vaccination was initiated. The response rate, antibody levels and persistence of antibody were directly related to the dose of vaccine and inversely to the age of children. No adverse reactions were observed.