OBJECTIVE The incidence of subsequent symptomatic mesenteric vascular disease is unknown for patients who have asymptomatic mesenteric arterial stenosis. The purpose of this study was to determine the risk of developing acute and chronic mesenteric ischemia in patients identified by lateral aortography to have significant mesenteric artery stenosis. METHODS From 1989 through 1995, 980 consecutive aortograms with anteroposterior and lateral projections were reviewed within 1 week of arteriography to identify patients who had significant mesenteric stenosis but no symptoms of mesenteric ischemia. Eighty-two patients were found to have 50% stenosis of at least one mesenteric artery and were monitored by interview to determine if symptoms of acute or chronic mesenteric ischemia developed. RESULTS Ten patients were lost to follow-up, and 12 patients were withdrawn from the study because of mild mesenteric arterial disease (1% to 49% stenosis) in combination with more significant disease of other vessels. Follow-up was 1 to 6 years. The overall mortality rate was 40%, and mesenteric ischemia developed in four patients. Each of these four patients had significant (>50%) stenosis or occlusion of the celiac artery, superior mesenteric artery, and inferior mesenteric artery. Eighty-six percent of the 15 patients with significant three-vessel arterial disease had mesenteric ischemia, had other vague abdominal symptoms, or died. CONCLUSIONS Patients with significant three-vessel mesenteric arterial stenosis should be considered for prophylactic mesenteric arterial reconstruction. Mesenteric arterial reconstruction should be routine when these patients undergo aortic reconstruction for aneurysmal or occlusive disease.