The purpose of the present study was to analyze in detail the kidney lesions of diabetic patients. Revision of the histopathologic aspects of this nephropathy was performed, seeking to approach the pathophysiology of its formation. In 200 consecutive necropsies of cadavers of diabetic patients examined at the Pathology Department of the Medical School of the São Paulo University, some degree of nephropathy was found in 158 cases. The slides from paraffin sections of these cases were reviewed according to a morphologic protocol previously established. Diffuse, nodular and mixed glomerulosclerosis were encountered in 42.2%, 21.5% and 5.7% respectively. Subcapsular drop and exudative lesion appeared in 12.7% and 15.2% of the cases. We also encountered arteriosclerosis in 81.6%, arteriolosclerosis in 88.6%, necrotizing papillitis in 11.4% and acute and chronic pyelonephritis in 23.4% and 20.9% respectively. We concluded that glomerular and vascular hyalin alterations were the most frequent findings in diabetic patients.