THROMBOSIS of the axillary and subclavian veins is a rare entity. In the statistical compilation by Barker et al of thromboembolic disease seen at the Mayo Clinic, 1 thrombosis of deep veins of the upper extremity represented only 1.7% of 1,260 cases. In a recent assessment by us of 2,400 episodes of deep venous thrombosis recognized over a 15-year interval, thrombosis of deep veins of the arm constituted 1.3% of the total. The largest single group of cases we have encountered in the medical literature is a series of 46 patients reported by Veal and Hussey in 1943 2 ; these individuals received no specific therapy. During the course of summarizing the results of anticoagulant therapy of deep venous thrombosis at our institution, we were impressed with a prognosis more favorable than expected 2,3 in 33 patients with deep venous thrombosis of the upper extremity who received anticoagulants for treatment of