Objective To investigate the change and significance of regulatory T lymphocytes in peripheral blood of rats model of chronic abacterial prostatitis.Methods Twelve Wistar rats with weight of approximate 390 g were randomly divided into two groups,model group and control group.Rats in the model group was injected subcutaneously 17β-estradiol(0.25 mg/day,for 30 days) after castration to establish rat model of chronic abacterial prostatitis.Flow cytometry was applied to detect the frequency of CD+4 CD+25 cells and CD+8CD-28 cells in peripheral blood of rats after model establishment.Results Compared with control group (11.63±1.36)％,the proportion of CD+4 CD+25T lymphocytes in model group (7.90±1.74)％ significanlty decreased (P＜0.01).Compared with control group (24.64±4.76)％,the proportion of CD+8CD-28T lymphocytes in model group (17.18±2.83) ％ also significantly decreased (P＜0.01).Conclusions The changes of the ratio of CD+4 CD+25T lymphocytes and CD+8CD-28T lymphocytes in peripheral blood of rats model of chronic abacterial prostatitis provided evidences for pathogenic mechanism of regulatory T lymphocytes participating in the development of chronic abacterial prostatitis.