MRL/lpr mice suffer from a systemic lupus erythematosus-like autoimmune disease. We studied the effects of oral treatments with Ninjin-youei-to (NYT, Ren-shen-yang-rong-tang, 1000 mg/kg/day), a suboptimal dose (2 mg/kg/day) of prednisolone(PSL) and their combination on nephritis in MRL/lpr mice. Treatments with NYT or PSL alone inhibited the development of proteinuria and prolonged survival. The combined treatment reduced the incidence of proteinuria and prolonged survival. In histological analysis, NYT treatments decreased the degree of mesangial proliferative glomerulonephritis and infiltration of mononuclear cells in the kidneys. PSL treatment was effective in reducing periglomerular nephritis and vasculitis in addition to such effects as NYT and NYT plus PSL treatment was more effective than PSL alone. The active form of TGF-beta was reduced in NYT and PSL-treated mouse serum, and the combined treatments further suppressed it. However, the treatment with NYT alone did not induce a decrease in the latent form of TGF-beta. The effect of NYT can be assumed to be different from an immunosuppressive effect of PSL. Therefore, the combined treatment with NYT and PSL can be expected to be more useful for the therapy of autoimmune disease such as nephritis, compared with NYT or PSL alone treatments.