Abstract: Objective To understand the hepatitis B infection and HBVS gene variation among high school students in Hamiencity, Jiang su province.Methods A serological survey of hepatitis B was conducted in a high school with cluster sampling method.HBsA gandanti HB were detected with EL ISA, and phylog enetic analysis for HBVS gene with nested PCR.Results HBs Ag positive rate was 6.39% and the rate for the students born at home, town ship health centers, and hospital above the county level was 11.76%, 8.02%, and 2.27%, respectively, with significant difference(P < 0.05).The percentage of the students with antiHBs titer 10U/l was 72.5%, and the titer distribution was Ushaped.The difference in antiHBs titer between boys and girls, a swell as different towns, was statistically significant(P < 0.01).All genotype of HBVS gene was C type, and the main variation was in protein hydropho bic area.The change of mimunogenicity in antigenic deter minant a zone was not observed.Conclusion The level of health careat birth can affect the HBV infection among high school students in Hamien.S gene variation occurs through positive selection, but not antigenicity.