Abstract: Objective This investigation was to have a better understanding of serological immuniza tion against hepatitis B and immunological efficacy among children aged between 3 and 12 in Dongcheng District Methods 3—12 years old children from 8 investigation points were selected to be adminis tered questionnaire and to be collected venous blood by using multi-stage cluster systematic random sampling，and 3 indexes of HBV were determined by radioimmunoassay. For children who had negative anti-HBs or a titer less than 10mIU／mL，a reinforced immunization at 2.5 and 5μg was managed and anti-HBs inspection was conducted within 1 to 3 months after immunization Results in Dongcheng District，the positive rate of HbsAg，anti-HBc and anti-HBs among children aged between 3 and 12 was 0.24％，5.20％and 52.01％respectively；the protection rate among children against Hepatitis B was 93.2％ and the mean titer of surface antibody was 73.46 mIU／mL. Among groups of different ages，there was no significant difference for the positive rate of HBsA4g,anti-HBc and anti-HBs.152 children underwent reinforced immunization for once and the overall positive conversion rate and mean titer of antibody after immunization was 88.8％ and l00.796 mIU／mL respectively，for which there existed no sig nificant difference between 2.5μg and 5μg group Conchusion For newborns in Dongcheng District.inocula tion of hepatitis B vaccine according to a 0，1 and 6-month procedure effectively block the transmission of hepatitis B and moreover，good protection can be achieved using either plasma-derived or genetic engineering Hepatitis B vaccine which is able to last for l2 years so that extensive reinforced inoculation is not necessary；for children with negative anti-HBs，reinforced inoculation of 2.5 μg or 5μg of Hepatitis B vaccine for only once can achieve a good immunological efficacy.