An experiment on dogs was conducted in order to study the hemodynamics of both common iliac arteries during complete occlusion of one iliac artery and after its subsequent release. In each of four simulated clinical situations, blood flow in the contralateral vessel decreased significantly after release of the occluded artery. Contralateral pressure changed little. Aortic flow increased upon release of the occlusion, as did both flow and pressure in the previously occluded artery. Mention is made of recent reports concerning borrowing-lending phenomena in the aortoiliac segment, and the name "iliac steal" is proposed to describe the "stealing" of blood flow from one common iliac artery by reopening an occlusion in the contralateral vessel. This phenomenon appears to be accentuated by stenoses in the aorta or in the contralateral vessel or in both sites.