The significance of necrosis (karyorrhexis), among the most characteristic findings in lupus nephritis, was evaluated by studying the correlation between the existence of necrosis in renal biopsy specimens and laboratory findings. The subjects were 54 patients with diffuse proliferative lupus nephritis and 6 patients with focal proliferative lupus nephritis selected from 143 patients with lupus nephritis. We also compared the clinical course of oral prednisolone and intravenous methylprednisolone pulse therapies after steroid administration. Compared with the non-necrosis group, the necrosis group had significantly lower CH50 levels and more proteinuria. Patients with necrosis were effectively treated with repeated pulse therapy judging by immunological activity and the decrease in proteinuria at an early stage, but responded poorly to oral steroid therapy. As the presence of necrosis in cases of lupus nephritis means high immunological activity of the lesion and there is responsiveness to a large dose of steroids, extensive immunosuppressive therapy including methylprednisolone pulse therapy should be applied to these patients.