Twenty-six peripheral arterial emboli complicating 14 cases of mural thrombi of the aorta were diagnosed between January 1978 and December 1986. None of these patients had any cardiovascular history; their mean age was 49 years. Presenting signs were acute ischemia of the lower limbs in 12 cases and chronic ischemia in two. Arteriograms and CT scan were diagnostic. The mural thrombi were infrarenal in 13 cases and suprarenal in one. Treatment of the thrombus was surgical in all but one patient. In four cases, treatment of the underlying cause was simultaneous with embolectomy; in nine patients, treatment was secondary because further workup was needed. In one case, the patient died following embolectomy before definitive treatment could be undertaken. Results were considered good in 11 cases (unlimited walking distance, no recurrent emboli), and poor in three cases (two major amputations and one death). The incidence of mural thrombi is not known. In our experience, they accounted for 3.8% of nonaneurysmal aortoiliac lesions operated upon during a nine-year period and were responsible for 5% of peripheral arterial emboli. Mural thrombosis of the aorta constitutes a dangerous condition with a potentially lethal final outcome. Recurrent emboli are inevitable without surgical treatment of the source.