Abstract: Objective To evaluate the efficacy of immunization of hepatitis B vaccine(HBV)introduced into EPI in Shaanxi province.Methods The survey was carried out to obtain the coverage rate of hepatitis B vaccine and the serum data of 1671 children by stratified random sampling method in 2002.A multistage cluster-randomized sampling was designed to survey 360 children for seroepidemiology of hepatitis B vaccine in 2006.Results After the hepatitis B vaccine was integrated into EPI,the first dose timely vaccination rate increased from 48.84% in 2002 to 84.77% in 2006,and the whole course vaccination rate increased from 53.37% in 2002 to 91.25% in 2006.The whole course timely vaccination rate of HBV increased from 48.24% in 2002 to 83.84% in 2006.There were significant statistical differences in the three coverage rates(P<0.001).The first dose timely vaccination rate was only 57.45% for infants born athome.For the 360 children under 4 years old in 2006,positive rate of HBsAg and anti-HBs was 1.39% and 70.56% respectively.Compared with the data in 2002,the positive rate of HBsAg declined and positive rate of anti-HBs raised to 213.32%.Conclusion The efficacy of HBV was improved after the HBV was introducd into EPI.But the first dose timely vaccination rate is still low.To keep the high HBV rate is the main task in the future especially in the area with low hospital delivery rate.