Coronary vascular disease is one facet of a generalized disturbance of vascular function present throughout the vascular tree. Dysfunction of the endothelium leads to thickening of the intima and media of the vessel wall of large and medium-sized muscular arteries and large elastic arteries, such as the aorta, carotid, and iliac arteries. Flow-mediated dilatation of the brachial artery is one of several tests used to assess dysfunction of the endothelium using high resolution ultrasound. Endothelial dysfunction has been demonstrated in children with heterozygous familial hypercholesterolemia, type 1 diabetes, morbid obesity, and homozygous homocystinuria and in the offspring of a parent with early coronary disease. High resolution ultrasound has also confirmed postmortem findings that atherogenesis has its beginnings in childhood and adolescence, with the demonstration of increased carotid artery intima-medial thickening in children with familial hypercholesterolemia, familial combined hyperlipidemia, and type 1 diabetes and in the offspring of a parent with early coronary disease. In combination with family history and traditional risk factors, ultrasound evaluation of brachial artery flow-mediated vasodilation and carotid artery intima-medial thickening could be used in a clinical setting to assess coronary risk in high risk pediatric patients.