Abstract: Objective: To investigate the changes of plasma interleukin-17A(IL-17A) level in patients with systemic lupus erythematosus(SLE) and analyze the clinical implication. Methods: Plasma IL-17A level was measured by ELISA from 60 SLE patients(13 without glucocorticoid treatment and 47 with glucocorticoid treatment) and 29 healthy persons. The relationship between IL-17A and clinical or laboratory parameters of SLE patients was explored. Results: IL-17A levels were elevated significantly in SLE patients without glucocorticoid treatment than in SLE patients with glucocorticoid treatment or healthy persons(P ＜ 0. 05-P ＜ 0. 01) . The negative correlation was observed between IL-17A expression and C4, erythrocyte sedimentation rate(P ＜ 0. 05) , but no correlation with C3, IgG, anti ds-DNA antibody, SLE disease activity index score and 24 h urine protein excretion(P ＞ 0. 05) . Conclusions: The level of plasma IL-17A in SLE patient without glucocorticoid treatment was higher than in normal control. IL-17A might play an important role in the pathogenesis of SLE. Treatment with glucocorticoid can decrease IL-17A level in SLE significantly.