We compared mean extent of atherosclerotic lesions in carotid and intracranial arteries at autopsy among age, sex, and race subgroups in New Orleans. Most comparisons were made within similar broad cause-to-death categories after excluding deaths due to diseases associated with increased amount of atherosclerosis. Use of this basal group of cases reduces the effect of selection bias due to cause of death in this autopsy population. Fatty streaks were present in the carotid arteries of almost all cases even in the youngest age group (10 to 14 years) and were more extensive in blacks than in whites. Raised atherosclerotic lesions increased with age in the carotid arteries of blacks from age group 15 to 24 years and in whites from age group 25 to 34 years; black men and white men had about the same amount of raised lesions, whereas black women consistently had more than white women. In the intracranial arteries, fatty streaks and fibrous plaques began from age 15 to 24 years; blacks had more raised lesions than whites, particularly in the oldest age group, 65 to 69 years. These findings and mortality data suggest that in the 1960s and early 1970s black men and women were more susceptible to cerebral atherosclerosis and cerebrovascular diseases than white men and women.