Eleven patients with vascular sequelae of thoracic outlet syndrome were operated on at the University of California, SanFrancisco, during the past 17 years. Five patients presented with episodes of ischemia of the arm and hand secondary to microemboli released from subclavian arterial lesions produced by chronic compression at the thoracic outlet. Treatment consisted of arterial reconstruction, removal of the compressive structure, and cervical sympathectomy to relieve or lessen distal ischemia. Four of the five patients had good or excellent results; one patient required amputation of the forearm. The results were inversely proportional to the extent of distal arterial embolic occlusions present at the time of surgical treatment. Six patients presented with symptoms of chronic venous hypertension. Four of the six had subclavian venous thrombosis and were treated by transaxillary resection of the first rib to decompress the collateral veins within the costoclavicular space. All four were symptomatically improved. Two patients had venous hypertension due to extrinsic compression of the subclavian vein. One patient became asymptomatic and the other was markedly improved after resection for external compression. In this small series transaxillary resection of the first rib has resulted in symptomatic improvement in chronic venous hypertension of the arm.