Objective To detect the ratio of CD4+ and CD8+ T cells and the number of CD4+CD25+ T regulatory cells(Treg)in human peripheral blood mononuclear cells(PBMC)of rheumatoid arthritis(RA)patients and evaluate the significance for diagnosis of RA.Methods The number of CD4+,CD8+ T cells and Treg cells were detected by flow cytometry and the ratio of CD4/CD8 was calculated.Results The ratio of CD4/CD8 and the number of CD4+CD25+ T cells detected in 49 RA patients were significantly higher than that in health group with statistical significance(P<0.05,P<0.01).The number of Treg cells in 28 RA patients after therapy was significantly higher than that before therapy(P<0.01),while no significant change of CD4/CD8 ratio.Conclusion The number of Treg cells increased significantly in RA patients whose symptoms were moderated.We think the number of Treg cells may closely related to the occurrence and development of RA.