Two hypertensive men with DeBakey type III dissection were admitted due to acute onset of leg ischemia.One patient had ischemia of both legs,The other patient had ischemia of the right leg.Angiograms showed occlusion of aortic bifurcation in one patient and occlusion of right common iliac artery and right renal artery in the other patient.The first patient who had ischemia of both legs was relieved by axillo-bifemoral bypass operation and the second patient with right leg ischemia by femoro-femoral bypass.The dissection of the aorta was successfully managed by conservative measures including hypotensive medication.The bypass grafts was functioning well one year later.The aortic dissection should not be overlooked as an etiology of acute onset of ischemia of the lower extremities.