Immunohistological study of 123 kidney biopsies of non-glomerulonephritic kidney diseases showed that deposits of immunoglobulins are found more often in cases of malignant than in cases of benign nephrosclerosis. Primary malignant nephrosclerosis is mostly associated with glomerular deposits of immunoglobulins. Positive immunohistological findings are frequent in cases of diabetic glomerulosclerosis, mainly within glomeruli, but also in tubular basement membranes and Bowman's capsule. In cases of glomerular amyloidosis we see cloudy-bandlike deposits, but are unable to differentiate cases with or without the nephrotic syndrome. If we consider an immunopathogenetic mechanism for the diseases discussed in terms of the present findings, it seems possible for primary malignant nephrosclerosis as well as for certain glomerular changes associated with acute renal failure or rejection of transplants. In diabetic glomerulosclerosis (apart from special forms with perimembranous lesions) and glomerular amyloidosis, we consider such a mechanism to be unlikely. By separating the non-glomerulonephritic diseases into different types of deposits we found pictures that correspond with immunocomplex diseases. Pictures resembling anti-basement membrane diseases have not been seen. Characteristic patterns of deposits were not found, thus immunohistology is without additional diagnostic value in the field of non-glomerulonephritis disease.