No age is exempt from the lesions of arteriosclerosis if we consider the two groups. However, the disease is seen for the most part in persons past middle life. The relative frequency with which it is found in the different decades depends on so many factors that it is of no value to tabulate them. As has been stated, arteriosclerosis of all types is an involution process that advances with age. Longevity is a question of the integrity of the arterial tissue, and no one can tell what sort of "vital rubber" (Osler) any one of us has. However, many with poor tubing may make such use of it that it will outlast good tubing that is badly treated. Unfortunately we have no way of telling early enough with just what sort of arterial tissue we are starting life. =Sex= There is no doubt that men are far more prone to arterial disease than women are; all statistics are in accord on this point. This is explained by the greater exposure of men to those conditions of life which tend to produce circulatory strain, and so to produce arteriosclerosis, or vice versa. Arteriosclerosis in women is not often seen until after the fiftieth year. Cases of the most extreme grade of pipe stem arteries are, however, seen in old women, and calcified arteries are not hard to find among the inmates of an old woman's home. =Race= Some of the most beautiful examples of arteriosclerosis in this country are seen in the negro. Not only is this disease more frequent in the black race, but the age of onset is much earlier than in the Caucasian. The accidents of arteriosclerosis, viz., aneurysm, cerebral hemorrhage, etc., are more common among the negro males. The etiologic factors that are most often found in the history are the prevalence of syphilis and hard physical labor. =Occupation=