In a cooperative multicenter study, Pathobiological Determinants of Atherosclerosis in Youth, of 1164 young men 15 through 34 years of age who died of external causes and were autopsied in forensic laboratories, we measured atherosclerosis of the aorta and the right coronary artery. Using the ratio of intimal thickness to outer diameter of the small renal arteries to predict mean arterial pressure (MAP) during life, we classified the cases as either normotensive (MAP < 110 mm Hg) or hypertensive (MAP > or = 110 mm Hg). By this criterion, the prevalence of hypertension in blacks was 16%; in whites, 12%. Hypertension was associated directly with blood level of glycohemoglobin (an indicator of blood glucose concentration) and with body mass index (BMI) but inversely with thickness of the panniculus adiposus. Among hypertensive compared with normotensive cases, the extent of raised lesions (mainly fibrous plaques) was greater in the aortas of 30- to 34-year-old men and in the right coronary arteries of 25- to 34-year-old men. The prevalence of raised lesions involving 5% or more of the intimal surface was twofold greater in the aortas and right coronary arteries of hypertensive men throughout the 15-to-34-year age span of the study cases. The association of hypertension with raised lesions was not accounted for by adjusting for glycohemoglobin level, BMI, or thickness of the panniculus adiposus. Hypertension is associated with accelerated atherosclerosis in youth.