Anomalies of origin of the brachiocephalic vessels are uncommon. The authors report a new case of such an abnormality revealed by a subclavian steal syndrome. The angiographic study showed a right aortic arch with hypoplasia of the origin of the left subclavian a., which arose from the descending aorta, and a collateral cervical circulation derived from the left vertebral a. and the right subclavian a.