目的　研究乙型肝炎的远期免疫效果。方法　采用单纯随机方法连续 13年对 1986年出生并接种乙型肝炎疫苗的儿童进行隔年随访 ,采血检测HBsAg、抗 HBs、抗 HBc。结果　 13年间HBsAg阳性率在 0 46 %～ 0 97%之间 ,未随免疫时间的延长而上升 ,乙型肝炎疫苗的远期保护效果为81 67% ,与近期免疫效果相当。结论　免疫后 13年仍无需加强免疫 Objective To study the long-term effect of hepatitis B immunization. Methods Children were randomly divided into three groups. The children born in 1986 and vaccinated with hepatitis B vaccine were followed up for 13 consecutive years. Blood samples were collected for detection of HBsAg, anti-HBs and anti-HBc. Results The positive rate of HBsAg in 13 years was between 0 46% and 0 97%, which did not increase with the prolongation of immunization time. The long-term protection effect of hepatitis B vaccine was 81 67%, which was comparable to the recent immunization. Conclusion There is still no need for booster vaccination 13 years after immunization