Arterial wall structure and function, an important determinant of cardiovascular (CV) disease, are influenced by CV risk factors, especially high levels of blood pressure and low-density lipoprotein cholesterol (LDLC). However, the differential impact of these two risk factors on arterial structure and function in healthy, asymptomatic younger adults is not clear. This aspect was examined in 1003 black and white adults aged 23-43 years enrolled in the Bogalusa Heart Study. Carotid artery intima-media thickness (IMT) (an average of common, bulb and internal carotid on both sides) and aorta-femoral pulse wave velocity (PWV) measured by B-mode ultrasound were used as indicators of artery structure and function. Values of IMT (0.83 mm) and PWV (5.4 m/sec) in blacks were significantly higher than IMT (0.80 mm) and PWV (5.2 m/sec) in whites, respectively (p < .01 for both). Although PWV was positively and significantly associated with carotid IMT in both races, this relationship was not different between blacks (regression coefficient, b = 1.75, p < .01) and whites (b = 1.41, p < .01) after adjusting for race, sex, age and body mass index. LDLC was significantly associated with carotid IMT in terms of standardized regression coefficient (b = 0.182, p < .01), but not with PWV (b = 0.045, p = .16). The association of systolic blood pressure with PWV (standardized regression coefficient, b = 0.337, p < .01) was stronger than the association with carotid IMT (b = 0.190, p < .01). These results indicate that adverse levels of LDLC and blood pressure play different roles in the development of arterial wall stiffness and atherosclerosis. Ultrasound measurements are helpful in assessing CV risk.