Objective To investigate the clinical efficacy of adefovir dipivoxil in antiviral treatment of chronic hepatitis B and its effect on peripheral blood T lymphocyte subsets.Methods 40 cases of patients with chronic hepatitis B were selected from The Fourth People’s Hospital of Qinghai in October 2009 to June 2012,the patients were given the antiviral treatment of adefovir dipivoxil.Before treatment,3 months,6 months and 12 months after treatment,the changes of liver function indicators of alanine transaminase(ALT),aspartate transaminase(AST)and total bilirubin(TBiL),and hepatitis B virus-DNA(HBV-DNA)were recorded;the total effective rate was observed;the peripheral blood T lymphocyte subsets changes was tested and analyzed by flow cytometry.Results The ALT,AST and TBiL of the patients all improved good,and the indicators of ALT,AST and TBiL after 12 months decreased significantly than before treatment,the HBV-DNA testing of the patients recovered negative,the difference was statistically significant (P<0.05 );the total effective rate of hepatitis B patients is 92.5%;the peripheral blood T lymphocyte subsets has no significant improvement in patients after antiviral treatment for 3 months.After the treatment for 6 months and 12 months,the CD4 +T and CD4 +/CD8 +T were significantly higher than those before treatment,there was no significant changes in CD3 +T and CD8 +T before and after treatment.Conclusion Adefovir dipivoxil has a good clinical efficacy in antiviral treatment of chronic hepatitis B,and can significantly improve the patients’liver function,improve peripheral blood T lymphocyte subsets imbalance.