The objective of this study was to investigate the relationship of flow-mediated dilatation and intima-media thickness (IMT) with coronary risk in African Americans (AAs). Endothelial dysfunction and IMT of carotid arteries are considered early steps in atherosclerotic disease process and have been used as surrogate markers of subclinical atherosclerosis. Data were collected on 106 AAs with a mean age of 64.0+/-6.6 years. Carotid artery IMT was measured with B-mode ultrasonography, as was brachial artery diameter at rest, during reactive hyperemia, and after nitroglycerin. Percent change in flow-mediated dilatation (%FMD) was defined as 100x(diameter during reactive hyperemia - resting diameter)/resting diameter. Percent change in nitroglycerin-mediated dilatation (%NMD) was defined as 100x(diameter with nitroglycerin-resting diameter)/resting diameter. The Framingham 10-year risk score (FRS) was calculated for each patient using the National Cholesterol Education Program (NCEP) risk score calculator and participants were categorized into 3 groups with FRS as <10%, 10% to 20%, and >20%. Thirty-eight participants had risk scores <10%, 26 had 10% to 20%, and 42 >20%. There was a significant inverse relation between %FMD and FRS (P<.0001) and between %NMD and FRS (P<.001). IMT was not statistically different among the risk groups. Endothelial dysfunction assessed by FMD significantly correlates inversely with FRS in AAs. FMD, an index of arterial compliance, appears to be a sensitive and reliable index of cardiovascular disease.