This study was done to emphasize the importance of early, accurate diagnosis of arterial aneurysms that show the symptoms of venous obstruction. Fourteen patients were identified as having atherosclerotic aneurysms producing venous compression. Nine patients had popliteal aneurysms, causing popliteal vein thrombosis in three patients and vein compression without thrombosis in six patients. Five patients had iliac artery aneurysms, producing left iliac vein thrombosis in one patient and venous compression without thrombosis in four patients. In 10 patients the cause of the venous compression symptoms was correctly identified and appropriate revascularization was performed with successful results. In four patients, two with iliac artery aneurysms and two with popliteal artery aneurysms, the associated aneurysm was not identified. One patient died of a ruptured aneurysm and three patients had below-knee amputations because of untreatable distal ischemia. Inappropriate treatment of patients with venous obstruction from unrecognized arterial aneurysms is associated with unacceptable morbidity and mortality. Accurate diagnosis with timely aneurysm repair eliminates the risk of aneurysm rupture or thrombosis and simultaneously alleviates venous compression symptoms.