Fifteen instances of intramural coronary arteries were observed in the dissection of 276 human hearts at consecutive unselected autopsies. All but 2 of these 15 had severe atheromata and narrowing of the lumina. It was thought important to determine whether or not the covering of the artery by cardiac muscle for a major part of its course protected the artery from atherosclerosis. From our data, one may assume that those portions surrounded by heart muscle were not protected from atherosclerotic process which occurred there as well as in extramural portions of the same arteries and in other entirely extramural coronary arteries.