It has become apparent in recent years that atherosclerosis, particularly of the coronary arteries, can no longer be regarded as the natural result of old age or as a medical curiosity when it occurs in the early decades of life. It is no longer rare in practice to encounter men under 40 who have fallen victim to disease of the coronary arteries, as manifested by coronary thrombosis or uncomplicated angina pectoris or both, long before they have reached the peak of their usefulness. It seems important, therefore, to determine how frequently serious coronary disease attacks persons in youth and early middle age and what its clinical characteristics in such persons may be. Furthermore, if clues are to be discovered that may aid in its prevention or disclose any underlying causative factors, exclusive of the aging process, the younger patients must be studied carefully. It was with these thoughts in mind