Patients with diabetes mellitus are at high risk of arteriosclerotic complications. The same is true for those with chronic renal failure (CRF). The present study evaluated clinical factors on the occurrence of peripheral arterial diseases. The severity of peripheral arterial disease was defined as mild (plaque, calcifications) or severe (70% stenosis, obstructions) based upon ultrasonographical examination. Overall in diabetic patients, mild ultrasonographical findings such as plaque and calcification were observed in 25% (17/69) of predialysis patients and in 18% (7/38) of those on hemodialysis (HD). Severe arteriosclerotic findings such as stenosis and obstruction were seen in 42% (29/69) of predialysis patients and in 50% (19/38) of those on HD. The incidence is identical between predialysis patients and patients on HD, regardless of the severity of peripheral arterial diseases. In an attempt to compare diabetics with non-diabetics, the incidence of mild abnormal findings was found in 22% (24/107) of diabetics and in 30% (11/37) of non-diabetics. Similarly, the percentage of patients with severe arteriosclerotic findings was found in 45% (48/107) in diabetics and 11% (4/37) in non-diabetics. The incidence of the severe type findings in the diabetics is significantly more frequent than that in the non-diabetics (P < 0.01, by the chi(2) test). In non-diabetic predialysis patients, the incidence of mild arteriosclerotic findings was observed in 30% (7/23), and 29% (4/14) of non-diabetic patients on HD. Similarly, the percentage of severe type was 9% (2/23) in non-diabetic predialysis patients, and 14% (2/14) in non-diabetic patients on HD. These data are not only supportive of previous data that diabetes is a risk factor for arteriosclerosis, but also suggestive that, even before the initiation of dialysis, patients with CRF are already susceptible to arteriosclerotic assault of peripheral arterial complications.