ABSTRACT
<p><b>OBJECTIVE</b>To investigate the positive rate of hepatitis B surface antibody (HBsAb) in children.</p><p><b>METHODS</b>Blood samples from 3022 children who received a physical examination in outpatient departments from 2009 to 2011 were subjected to serological test using ELISA to measure the positive rate of HBsAb.</p><p><b>RESULTS</b>The positive rate of HBsAb decreased with age (P<0.01). There was no significant difference in the positive rate of HBsAb between boys and girls (P>0.05), however the positive rate of HBsAb in boys aged one year and over was lower than in girls of the same age (P<0.01). The positive rate of HBsAb in boys aged between 3 and 4 years was higher than in girls of the same age (P<0.01). The positive rate of HBsAb decreased with age in boys, and was lower in those aged two years and over than in those aged one year and over (P<0.01). The positive rate of HBsAb also decreased with age in girls, with significant differences between different age groups (P<0.01).</p><p><b>CONCLUSIONS</b>The positive rate of HBsAb decreases with age in children, so younger children have a higher risk of infection with hepatitis B virus. Serological monitoring of hepatitis B needs to be enhanced.</p>