Twenty renal biopsies from 13 patients with systemic lupus erythrematosus were examined in detail to assess the amount and distribution of electron-dense deposits. Results were correlated with clinical and histologic findings. Mesangial deposits were present when there were deposits in other areas. Subepithelial deposits were not associated with severe renal disease and tended to persist unchanged with time. Subendothelial deposits were not invariably associated with severe renal disease, but, when severe disease existed, large subendothelial deposits were found. These deposits disappeared with treatment and clinical improvement.