First rib fractures occurred in 55 patients. This injury is a harbinger of major trauma with 35 patients suffering a major chest injury, and abdominal and cardiac injuries occurring in 18 and eight patients respectively. The mortality associated with this injury was high (36.3%). Neurologic lesions accounted for the majority of deaths, however, unrecognized abdominal injuries and pulmonary complications were significant causes of mortality. Brachial plexus injury (5) and Horner's syndrome (3) occurred in survivors. Three patients had an associated injury of the subclavian artery, and the importance of this association is stressed. One late-developing post-traumatic thoracic outlet syndrome occurred. A fracture of the first rib is a hallmark of severe trauma; its presence should alert the clinician to: 1) generalized massive trauma with abdominal, chest, and cardiac injuries; 2) local injury to the subclavian artery and brachial plexus and; 3) necessity of long-term followup for late-developing sequelae.