Branches of the renal artery were macroscopically isolated from autopsy kidneys and separated into four portions; the trunk outside the kidney (a. renal-O), the large subbranches inside the kidney (a. renal-I), aa. interlobares, and aa. arcuatae and interlobulares. Sclerosis was more prominent in the diabetics than in the nondiabetics in all of the four portions of the renal artery, especially in the smaller branches. Sclerosis was prominent even in the diabetics with glomeruli showing minimal histological changes. There was statistically significant correlation between the degree of glomerular hyalinization and sclerosis of aa. interlobares and aa. arcuatae and interlobulares. Statistically significant positive correlation was also observed with respect to the grade of sclerosis between any two of the four portions of the renal artery. These results suggest that arteriosclerosis of the renal artery is already prominent before the glomerular changes appear and further advances in parallel with glomerular hyalinization, especially in smaller branches.