The authors report the clinical and radiological study and the treatment of a fifteen members family (the two parents and their thirteen children) affected with a thoracic outlet syndrome secondary to a cervical rib and or an apophysomegaly of the seventh cervical vertebra. On the fifteen people considered, the father being deceased has not been examined but has an evocative clinical history. The mother has a clinical impairment with a late beginning and no radiological sign. Twelve children have clinical and radiological signs, one has radiological without clinical signs. Three children underwent a surgical treatment, the others only medical treatment. There is no satisfactory correlation between the clinical features and electrical investigations (electromyography, nerve conduction studies) and radiological examinations. The semiology is vascular, neurologic or mixt. Roos test seems more reliable than that of Adson, Calb and Roth, and Saunders. Eight grand-children out of fourty have been examined. Five have clinical and radiological signs, three have casual radiological signs. The radiological impairment of this family contrasts with the normal frequency of cervical anomalies in the population which is 0,12 to 1%. The family impairment of the thoracic outlet syndrome is rarely reported.