AIMS--To study immune deposits in renal glomeruli. METHODS--Tissue was obtained from 756 necropsy cases from people who had committed suicide or met with a violent death. Glomerular immune deposits were examined by immunofluorescence microscopy and a light microscopy. The clinical histories of all the decreased were studied to ascertain reasons for the deposits. RESULTS--Immune deposits were found in glomeruli in 91 (12%) cases. In 52 (6.8%) cases mesangial IgA was observed as a solitary finding in 34 (4.5%), and was accompanied by other immunoglobulins in 18 (2.4%). Mesangial IgM was present in 19 (2.5%) and IgG in 11 cases (1.5%). Two cases had capillary IgG (0.3%). Light microscopic examination showed mesangial enlargement in eight of the cases with mesangial IgA. These included one with IgA glomerulonephritis diagnosed before death. Two cases with normal glomerular morphology and mesangial IgA deposits had clinical laboratory evidence of renal disease. In two subjects with normal glomerular morphology, mesangial IgM and microscopic haematuria were present. In one case with capillary IgG membranous glomerulonephritis was detected. CONCLUSIONS--Ten cases had mesangial IgA together with morphological or clinical laboratory findings suggestive of renal disease. If all these are regarded as IgA glomerulonephritis, then its prevalence can be estimated at 1.3%. For IgM glomerulonephritis, a prevalence of 0.3% was deduced.