目的：观察儿童乙型肝炎表面抗体（HBsAb）阳性率情况。方法对2009~2011年3022例在门诊行健康体检的儿童采用酶联免疫法进行乙肝血清学检测，分析HBsAb阳性率。结果HBsAb阳性率随年龄增高而降低（P0.05)，但1岁~组男孩HBsAb阳性率低于女孩(P<0.01)，而3~＜4岁组男孩HBsAb阳性率高于女孩(P<0.01)。男孩组中HBsAb阳性率随年龄增高而降低，2岁~组男孩HBsAb阳性率低于1岁~组（P<0.01）；女孩组中HBsAb阳性率亦随年龄增高而降低，且各年龄组之间两两比较差异均有统计学意义（均P<0.01）。结论HBsAb阳性率随儿童年龄增高而降低，且低龄儿童是感染乙型肝炎的高危人群，需要加强乙肝血清学监测。

OBJECTIVE: To investigate the positive rate of hepatitis B surface antibody (HBsAb) in children. METHODS: 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. RESULTS: The positive rate of HBsAb decreased with age (P0.05), 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). CONCLUSIONS: 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.