System lupus erythematosus (SLE) is an autoimmune disease with multicellular pathogeneic components. Recent studies suggest an important role for interferon-alpha (IFN) in the immunopathogenesis of SLE. Data demonstrating a correlation between IFN-alpha and SLE disease severity range from elevated IFN-alpha levels in patients' serum and induction of IFN-regulated genes in peripheral blood mononuclear cells, to drug induced lupus disease in hepatitis C or cancer patients treated with recombinant IFN-alpha. In addition, mouse models of lupus in which the IFNR is deleted fail to develop disease manifestations. Thus, targeting IFN-alpha promises to be therapeutically efficacious for SLE.