We describe a modular stent graft for use in endovascular repair of aneurysms of the aortic arch. Carotid-carotid and left carotid-subclavian bypass grafts are created surgically. Two large, fully stented grafts are inserted endoluminally. The proximal component is bifurcated, with a wide proximal trunk and two distal limbs, one long and narrow, the other short and wide. This component is inserted through the carotid artery and deployed with the trunk and short wide limb in the ascending thoracic aorta; the long narrow limb opens into the innominate artery. After delivery system removal and carotid artery repair, a distal component is inserted through a femoral approach to bridge the gap between the short, wide distal limb of the proximal component and the nondilated descending thoracic aorta. The result is a branched stent graft, implanted proximally into the ascending aorta and distally into the innominate artery and descending thoracic aorta. The system has been used successfully to treat a large wide-necked pseudoaneurysm of the aortic arch.