['This study attempted to assess whether coronary risk factors are associated with endothelial dysfunction in the systemic arteries of asymptomatic men and women.', 'Endothelial dysfunction is present in adults with established atherosclerosis. It is not known whether risk factors interact to produce endothelial dysfunction in clinically well subjects early in the natural history.', 'Using high resolution ultrasound, we measured arterial diameter at rest, after reactive hyperemia (with increased flow causing endothelium-dependent dilation) and after sublingual nitroglycerin (an endothelium-independent dilator). Arterial responses were studied noninvasively in 500 clinically well, nonhypertensive subjects (252 men, 248 women; mean [+/- SD] age 36 +/- 15 years, range 5 to 73), including 179 current and former smokers. The superficial femoral artery was studied in 46 subjects and the brachial artery in 454.', 'Flow-mediated dilation ranged from -1% to +17%. All arteries dilated in response to administration of nitroglycerin (17 +/- 6%), suggesting an abnormality of endothelial function in subjects with impaired flow-mediated dilation. On univariate analysis, reduced flow-mediated dilation was significantly related to hypercholesterolemia, cigarette smoking, higher blood pressure, male gender, older age, family history of premature vascular disease and larger vessel size (p < 0.01). By multiple stepwise regression analysis, reduced flow-mediated dilation was independently associated with cigarette smoking, older age, male gender and larger vessel size (p < 0.005) but not with total cholesterol level, blood pressure or family history. A composite risk factor score was independently related to flow-mediated dilation (r = -0.30, p < 0.0001), suggesting risk factor interaction.'] Does endothelium-dependent dilation in the systemic arteries of asymptomatic subjects relate to coronary risk factors and their interaction?