The usual complication of abdominal aortic aneurysms is rupture. Although thrombosis of peripheral aneurysms is common, thrombosis of abdominal aortic aneurysms is rare. Sudden thrombosis of abdominal aortic aneurysms constitutes a surgical emergency, with a mortality of 50 percent. The patient often presents with cool and mottled skin, and with severe pain from the umbilicus to the lower extremities. Femoral pulses are rarely present, and neurologic deficits below the level of occlusion are common. We reviewed four recent patients with thrombosed abdominal aortic aneurysms. They presented with a range of symptoms that included impotence, abdominal pain, lower extremity pain, coolness, and weakness. Angiography in three of the patients revealed complete occlusion of the aorta. The fourth patient did not undergo angiography because of hemodynamic instability. Three of the four patients underwent thrombectomy, aneurysmectomy, and bypass grafting. The other patient underwent axillofemoral bypass grafting in lieu of aneurysmectomy because of severe coronary arteriosclerotic heart disease. All patients did well postoperatively. Our limited experience suggests that prompt diagnosis and surgical management of patients with thrombosed aortic aneurysms can lead to a successful outcome.