Abstract: Objective To investigate the correlation between the percentages of T lymphocyte subsets( CD3+T,CD4+T,CD8+T,and CD4+/ CD8+T) and CD4+CD25+regulatory T cells( Treg cells) and hepatitis B virus( HBV) DNA level in the peripheral blood of chronic hepatitis B( CHB) patients. Methods We chose 175 patients with HBV infection,who visited The Second People' s Hospital of Lanzhou from July to December,2012. The patients were divided into CHB group( n = 63) group and asymptomatic carrier( ASC) group( n =112). In the same period,50 healthy examinees served as control group. The percentages of CD3+,CD4+,CD8+,and CD4+/ CD8+T lymphocytes and CD4+CD25+Treg cells in the serum of three groups were measured by flow cytometry. HBV DNA level was analyzed by quantitative real- time PCR. The comparison of means between multiple groups was performed by analysis of variance. Further comparison between any two means was performed by LSD- t test. Correlation analysis was performed by Pearson's correlation test. Results The percentage of CD4+CD25+Treg( 30. 97% ± 18. 78%) in the peripheral blood of CHB patients was significantly higher than that of the control group( 27. 30% ± 17. 59%)( P < 0. 05). Compared with the control group,the CHB and ASC groups had significantly reduced percentages of CD3+and CD4+T lymphocytes and CD4+/ CD8+T lymphocyte ratio( P < 0. 05) and a significantly increased percentage of CD8+T lymphocytes( P < 0. 05). There was a positive correlation between the percentage of CD4+CD25+Treg cells and HBV DNA level in the ASC and CHG groups( r = 0. 501 and 0. 682,P < 0. 05 for both). Conclusion There are normal percentages of T lymphocyte subsets in HBV infection patients. HBV DNA can lead to an increased percentage of CD4+CD25+Treg cells,indicating that the imbalance of CD4+CD25+Treg and CD4+/ CD8+T cells plays an important role in the chronic progression of hepatitis B.