A retrospective study of kidney tissues accessioned in the Department of Immunopathology was undertaken to determine the reliability of the direct immunofluorescence technic applied to necropsy tissues. Of 72 accessioned specimens, 27 were positive and showed a spectrum of immunomicroscopic patterns corresponding to different renal diseases. Only two patients whose specimens were negative by immunofluorescence had shown any clinical or light microscopic evidence of active glomerular disease. Periods from death to autopsy ranged from one to 20 hours. Positive fluorescence was found in tissues obtained as long as 20 hours after death. These findings suggest that immunofluorescent studies of autopsy-derived renal tissue yield acceptable results.