Complete infrarenal aortic occlusion was found in 20 of 325 patients who underwent bypass for atherosclerosis of the distal aorta. Eleven had normal distal arteries as demonstrated by arteriography; the remaining patients had multilevel areas of stenosis and occlusion below the inguinal ligament. The two groups were significantly different in age, blood pressure levels, and duration of symptoms. The bypass relieved symptoms and restored flow in all the patients with normal distal vessels. There were four acute graft failures, two of which resulted in death, in the group with distally diseased vessels, and only two of these nine patients were symptomatically improved by the bypass. These data indicate that there are at least two distinct patient populations with the Leriche syndrome. Anatomic changes at the aortic bifurcation may be responsible for the clinical differences.