The relationship between abdominal aortic aneurysms and peripheral arterial occlusive disease (arteriosclerosis obliterans [ASO]) was investigated by noninvasive methods in 86 patients. Forty-four percent of the patients had occlusive disease of the lower extremities when they were first seen with their aneurysms. In almost all cases, the disease was bilateral. There was no statistically significant difference between the operative mortality in patients with occlusive disease (12%) and those without occlusive disease (6.8%). Sixty-one patients were followed up to 12 years. In 44% of the patients with ASO, there was evidence of disease progression; while only 17% of those originally free of ASO developed occlusive lesions. Comparison of long-term survival of patients with and without peripheral occlusive disease revealed no statistically significant differences.