Abstract A case of syphilitic aneurysm of bifurcation of the innominate artery is presented. The aneurysm was resected, and primary anastomosis of the common carotid to the innominate artery was performed during twenty-four minutes of occlusion. The subclavian artery was sacrificed. The complication of hemiplegia following ligation of the common carotid artery is discussed. Methods of evaluating the likelihood of the development of hemiplegia are also briefly discussed. Early operative intervention is advocated to prevent cerebral damage from emboli. Early intervention is also easier when the lesion is small and has not greatly distorted the vessel and its surrounding structures. Attention is directed again to the advisability of entering the aneurysm prior to its excision to determine the limits of the diseased vessel and prevent unnecessary resection of normal artery, thus reducing the chance of primary anastomosis.