Objective To evaluate the changes of peripheral blood CD4+CD25+ regulatory T cells and its prognostic value in sepsis patients.MethodThe percentage of CD4+CD25+/CD4+ T cells were measured by flow eytometry present in peripheral blood in 36 sepsis patients on day 1,3 and 5 and 15 healthy people (control group).The changes of CD4+CD25+ regulatory T cells were analyzed in survivors group and non-survivors group respectively.Results There were 19 survivors and 17 non-survivors in sepsis patients.The percentage of CD4+CD25+/CD4+ T cells in survivors group and non-survivors group on day 1 was significantly lower than that in eontrol group [(12.42± 3.26)%,(12.96± 3.00)% vs (16.97 ± 3.66)%,P＜0.05].The percentage of CD4+CD25+/CD4+ T cells in survivors group and non-survivors group on day 3 were both signifieanfly higher than that on day 1 [(24.47±4.62)%vs (12.42±3.26)%,(26.61±3.85)%vs (12.96±3.00)%,P＜0.05].The percentage of CD4+CD25+/CD4+ T cells in survivors group on day 5[(18.28±4.28)%]was significantly lower than that on day 3 (P＜0.05),and the percentage of CD4+CD25+/CD4+ T cells in nonsurvivors group on day 5 were significantly higher than that on day 3(P＜0.05).There was no significant difference in the percentage of CD4+CD25+/CD4+ T ceils between survivors group and non-survivors group on day 1,3 respeefively(P ＞ 0.05),but the percentage of CD4+CD25+/CD4+ T cells in survivors group was significantly lower than that in non-survivors group on day 5 (P＜0.05).Conclusions The CD4+CD25+ regulatory T cells in sepsis patients decreases following by increase after onset.The persistent increase suggests the emergence of immunoparalysis,which is followed by high monaliy,The CD4+CD25+ regulatory T cells are valuable in evaluation of immune state and prediction the prognosis in sepsis patients.