Objective To investigate the effects of dexamethasone(DEX)on the secretion of interleukin (IL)-17 and interferon(IFN)-γ and the proportion of Th17,Tc17,Th1 ,Tc1 cells in peripheral blood mononuclear cells(PBMCs)of patients with systemic lupus erythematosus(SLE). Methods Thirty hospitalized SLE patients were recruited and twenty-two healthy volunteers were recruited as healthy controls. PBMCs were separated from SLE patients and healthy controls and then was cultured in vitro by medium or PMA/Ionomycin or PMA/Ionomycin +dexamethasone for six hours. Four- color immunofluorescent staining and flow cytometric assay were used to analyze the percentage of Th17,Tc17,Th1,Tc1 cells in PBMCs. Concentrations of IL-17 and IFN-γ in plasma and the supernatants of PBMCs which were cultured for 24 hours were measured by enzyme linked immunosorbent assay (ELISA). Results The plasma concentrations of IL-17 and IFN-γwere elevated in SLE patients as compared to the controls(P ＜ 0.05). No significant differences were observed between patients and controls for the spontaneous production of IL-17 and IFN-γ or percentage of T subsets expressed by PBMCs. After the stimulation of PMA,compared with the controls,the level of IL-17 was significantly elevated in the supematants of PBMCs and the percentages of Th17 and Tc1 in SLE patients increased significantly(P ＜ 0. 05). However,there showed no significant differences between SLE patients and the controls for the percentages of Th1 and Tc17 cells. DEX could significantly decrease the production of IL-17(P ＜ 0. 01)and the percentages of Th17,Tc1 cells by the active PBMCs(P ＜ 0. 05). Conclusions There is abnormal expression of T subset cells and their cytokines in vivo of SLE patients. DEX can interfere with immunological pathological process in the cytokine network imbalance of SLE patients and shows powerful inhibition of IL - 17. Our results may provide some laboratory evidence for the clinical application of corticosteroids.