The hypogastric artery is one of the major collateral arteries in aortoiliac occlusive disease. This report describes a case of limb-threatening ischemia caused by acute arterial thrombosis of the right hypogastric artery. The external iliac and distal arteries were obstructed and the hypogastric artery was a major collateral artery. A diagnostic arteriogram taken after intra-arterial thrombolytic therapy revealed a stenotic lesion in the orifice of the hypogastric artery. Open thromboendarterectomy of the hypogastric artery and patch angioplasty, using an expanded polytetrafluoroethylene graft, were performed to salvage the limb. The hypogastric artery was successfully revascularized and ischemic rest pain was relieved.