We found that patients with thoracic outlet syndrome have: (1) low-set, “droopy” shoulders and long swan neck; (2) pain in the neck, shoulder, chest, arms, or hands; (3) aggravation of symptoms by downward traction and relief by propping up the arms; (4) occurrence in women; (5) absence of abnormal vascular, neurologic, and electrical findings; (6) a Tinel9s sign over the brachial plexus; and (7) T-2 vertebra visible above the shoulders on lateral cervical spine films. In our experience, droopy shoulder syndrome has accounted for most cases of thoracic outlet syndrome but is largely unrecognized by physicians. Recognition of this syndrome should lead to a better understanding of the underlying pathophysiology and prevent unnecessary surgery.