AIM:To investigate the peripheral T-lymphocyte subpopulation profile,and its correlations with hepatitis B virus(HBV) replication level in chronic HBV-infected(CHI) individuals with normal liver function tests(LFTs) . METHODS:Frequencies of T-lymphocyte subpopu-lations in peripheral blood were measured by flow cytometry in 216 CHI individuals. HBV markers were detected with ELISA. Serum HBV DNA load was assessed with quantitative real-time PCR. Information of age at HBV infection,and maternal HBV infection status was collected. ANOVA linear trend test and linear regression were used in statistical analysis. RESULTS:CHI individuals had significantly decreased relative frequencies of CD3+,CD4+ subpopulationsand CD4+/CD8+ ratio,and increased CD8+ subset percentage compared with uninfected individuals(all P < 0.001) . There was a significant linear relationship between the load of HBV DNA and the parameters of T-lymphocyte subpopulations(ANOVA linear trend test P < 0.01) . The parameters were also significantly worse among individuals whose mothers were known to be HBV carriers,and those having gained infection before the age of 8 years. In multiple regressions,after adjustment for age at HBV infection and status of maternal HBV infection,log copies of HBV DNA maintained its highly significant predictive coefficient on T-lymphocyte subpopulations,whereas the effect of HBeAg was not significant. CONCLUSION:HBV DNA correlates with modification in the relative T-lymphocyte subpopulation frequencies. High viral load is more powerful than HBeAg in predicting the impaired balance of T-cell subsets. A investigate the peripheral T-lymphocyte subpopulation profile, and its correlations with hepatitis B virus (HBV) replication level in chronic HBV-infected (CHI) individuals with normal liver function tests (LFTs). METHODS: Frequencies of T-lymphocyte subpopu -lations in peripheral blood were measured by flow cytometry in 216 CHI individuals. HBV markers were detected with ELISA. Serum HBV DNA load was assessed with quantitative real-time PCR. Information of age at HBV infection, and maternal HBV infection status was collected. ANOVA linear trend test and linear regression were used in statistical analysis. RESULTS: CHI individuals had significantly decreased relative frequencies of CD3 +, CD4 + subpopulations and CD4 + / CD8 + ratio, and increased CD8 + subset percentage compared with uninfected individuals (all P <0.001). a significant linear relationship between the load of HBV DNA and the parameters of T-lymphocyte subpopulations (ANOVA linear trend test P <0.01). The parameters w ere also significantly worse among selected mothers were to HBV carriers, and those with gain infection before the age of 8 years. In multiple regressions, after adjustment for age at HBV infection and status of maternal HBV infection, log copies of HBV DNA maintains its highly significant predictive coefficient on T-lymphocyte subpopulations, whereas the effect of HBeAg was not significant. CONCLUSION: HBV DNA correlates with modification in the relative T-lymphocyte subpopulations frequencies. High viral load is more powerful than HBeAg in predicting the impaired balance of T-cell subsets.