Endarterectomy is an established method of restoring arterial circulation in a chronically obstructed artery. The technique has been carried out in a variety of anatomic sites and has recently been employed with varying success on human coronary arteries.1-3 There has, however, been a tendency toward late closure of small arteries after endarterectomy.4 This has prompted some surgeons to enlarge the lumen of the endarterectomized segment by patch grafts of plastic material5 or autogenous vein.6,7 Indeed, Senning8 has reported recently on "strip grafting" of the coronary arteries in the human. This study was undertaken to evaluate various methods of closure of incisions in the circumflex coronary artery in the dog. Methods Twenty-two adult mongrel dogs weighing from 11 to 18 kg. were employed in this study. The animals were anesthetized by intravenous administration of pentobarbital sodium in the amount of 25 mg. per kilogram, and respirations