The aim of this study was to research the expression of IL-37 in systemic lupus erythematosus (SLE) patients and the effect of glucocorticoid on IL-37. Thirty newly diagnosed severe SLE patients receiving prednisone 1 mg/kg/day for 14 consecutive days and 30 healthy subjects were enrolled into this study. The plasma levels of IL-37 and other cytokines were detected by ELISA and the relative mRNA amounts of IL-37 and other cytokines were detected by RT-PCR. The plasma levels of IL-37, IL-18, IL-18BP, IFN-γ, and IL-6 in SLE patients increased significantly compared with healthy controls (p<0.05). The relative amount of IL-37 mRNA increased by 2.45-fold in pre-treatment SLE patients compared with controls (p<0.05). Plasma concentrations of IL-37 correlated with IL-18, IL-18BP, IFN-γ, IL-6 and SLEDAI score in both pre-treatment and post-treatment SLE patients. The plasma levels of IL-37 decreased significantly after treatment of glucocorticoid. The relative amount of IL-37 mRNA decreased by 24.5 % in post-treatment SLE patients compared with pre-treatment ones (p<0.01). In conclusion, IL-37 is upregulated in active SLE patients. IL-37 is correlated with pro-inflammatory cytokines and SLEDAI. Glucocorticoid can downregulate the expression of IL-37 and other cytokines in SLE patients.