Diffuse intercapillary glomerulosclerosis and exudative glomerulosclerosis were produced in rats fed high-sucrose diet for periods of nine to eighteen months. These lesions were observed by light and electron miscroscopy. Impairment of glucose tolerance was observed in the sucrose-fed animals and marked proteinuria developed in the course of long-term sucrose feeding. Such lesions did not develop in a control group of age-matched fed high-starch diets.