Abstract： Objective To study the applied value of peripheral blood lymphocytes subsets monitoring in diagnosis of acute rejection (AR) and CMV infection in kidney transplant recipients.Method Seventy-nine kidney transplant recipients (52 cases of stable renal function,15 cases of AR,and 12 cases of CMV infection) were enrolled in this study according to the selection criteria.The lymphocyte subsets in peripheral blood were examined dynamically by flow cytometer.All the recipients received ATG induction therapy,and a triple-drug immunosuppressive regimen (CsA/Tac + MMF+ Pred) was given to all the patients.Results The percentage of CD3+ CD4+ cells in stable group,AR group and CMV infection group was 39.73 ± 8.59,48.75 ± 8.77,and 31.54 ± 11.09 respectively,of which the percentage of CD3+ CD4+ cells in AR group was significantly higher than that in stable group and CMV infection group (P＜0.05).The percentage of CD3+ CD8+ cells in stable group,AR group and CMV infection group was 28.96 ± 9.08,17.47 ± 5.92 and 42.48 ± 13.77 respectively,of which the percentage of CD3+ CD8+ cells in CMV infection group was significantly higher than that in stable group and AR group (P＜0.05).The ratio of CD4/CD8 in in stable group,AR group and CMV infection group was 1.75 ± 0.98,2.89 ± 0.69 and 0.63 ± 0.31 respectively,while the percentage of NK cells was 8.47 ± 4.33,15.24 ± 5.89 and 4.67 ± 1.89 respectively,with significant differences between the groups (P ＜ 0.05).The ratio of CD4/CD8 and NK cells was decreased to (1.76 ± 0.50) and (10.72 ± 6.79)％ respectively after remission of AR group as compared with that at the onset of AR (P＜0.05).Conclusion The monitoring of peripheral blood lymphocyte subsets,especially the dynamic changes of CD4/CD8 and NK cells,was of significance in the diagnosis of AR and CMV infection and the individualized immunosuppressive therapy for kidney transplant recipients.