Subclavian steal syndrome is a circulatory disorder usually caused by atherosclerosis and accompanied by ischemic symptoms of the vertebrobasilar region and the hand. In many cases, significant vascular lesions are found also in other arteries. In more than 80% of cases the blood vessel lesion is on the left, and a significant stenosis or occlusion causes an inter-arm pressure gradient of > 20 mmHg, resulting in retrograde blood flow of the ipsilateral vertebral artery. In local stenosis, conservative treatment can be combined with an intravascular procedure, and in occlusions or other arterial lesions requiring operative treatment, with bypass surgery.