MRL-Fas(lpr) mice spontaneously develop a systemic autoimmune disease resembling human systemic lupus erythematosus. The glomerulonephritis in MRL-Fas(lpr) mice is mediated by autoantibodies and autoreactive lymphocytes. To investigate the effect of combination therapy by angiotensin-converting enzyme inhibitor (ACEI) and hydroxymethylglutaryl-coenzyme A reductase inhibitor (statin) for lupus nephritis, we treated MRL-Fas(lpr) mice with imidapril, pravastatin or both agents. Compared with other groups, the mice treated by combination therapy survived longer and showed a significant reduction in proteinuria, renal pathology, including glomerular IgG deposit, and serum anti-DNA Ab. Furthermore, monocyte chemoattractant protein-1 (MCP-1) in the kidney was reduced significantly in the combination therapy group, compared with that in the control group. We conclude that combination therapy with ACEI and statin for MRL-Fas(lpr) mice significantly alleviates autoimmune renal disorder and prolongs survival. These results suggest that combination therapy by ACEI and statin may represent a new approach to the treatment of patients with lupus.