Recent evidence indicates that artesunate has immunomodulatory properties that might be useful for treating autoimmune disease. In this study, we conducted a pilot study and explored the effect and mechanism of artesunate on the treatment of systemic lupus erythematosus using an MRL/lpr murine model. MRL/lpr mice were divided into control, cyclophosphamide (CTX) and artesunate treatment groups. Blood was collected to measure serum levels of creatinine, antinuclear antibody (ANA) and anti-double-stranded DNA (anti-dsDNA) antibody. Twenty-four-hour urine was collected to measure levels of proteinuria. The concentration of monocyte chemotactic protein-1 (MCP-1) in serum and urine was measured. The expression of MCP-1 in kidney was detected by Western blot and immunohistochemistry assay, respectively. The expression of B cell activating factor (BAFF) in spleen was determined by real time-PCR and immunoblotting. We found that artesunate significantly increased the survival rate, body weight and blood leukocyte counts, and reduced the serum levels of ANA and anti-dsDNA antibody titer, 24 h urinary protein, and serum creatinine. Our results indicated that artesunate could decrease MCP-1, major pro-inflammation cytokine, in serum, urine and kidney. We also found that the level of BAFF, the major B cell activation factor, was decreased in artesunate treated MRL/lpr mice. Its efficacy was comparable with that of CTX in this study. Taken