Anomalous right subclavian artery, originating as the last vessel from the aortic arch, is one of the commonest anomalies of the great vessels. Anatomists have been familiar with this condition for more than two centuries, yet few clinicians are aware of its existence. Despite its frequency and the ease with which it can be detected roentgenologically, the correct diagnosis is seldom made during life. This is due, in part, to the fact that the anomaly is usually asymptomatic. Occasionally, however, severe symptoms may develop and progress to a fatal outcome. This anomaly has assumed greater significance with the advent of the surgical approach to the treatment of congenital malformations of the heart and great vessels. Gross (12), in 1946, successfully ligated an anomalous right subclavian artery. Since that time he has surgically cured 4 additional patients with symptoms related to this cause (13). Blalock (5) encountered the anomaly five times during operations on patients with the tetralogy of Fallot, ...