A 20-year-old man had avulsion of the innominate artery from the aorta caused by blunt trauma to the chest. A widened mediastinum on chest films is the best indicator that such an injury may be present. During repair, the right common carotid blood pressure should be measured by direct arterial puncture after proximal clamping. A distal stump pressure of 50 mm Hg or greater indicates that there is adequate collateral flow via other systems and a shunt will therefore not be necessary. If there is not sufficient collateral flow, then a graft should originate from a new site on the ascending aorta in end-to-side fashion and be sutured distally to the innominate bifurcation or common carotid artery.