['Reduced endothelial-dependent arterial dilatation (EDAD) has been suggested as an early marker of arteriosclerosis, since it has been reported to correlate with known cardiovascular disease (CVD) risk factors. It is unclear, however, whether gender plays a mediating or a moderating role in these relationships. The aim of this study was to evaluate the influence of gender on EDAD in youth at risk for CVD.', 'The sample population of 261 individuals (mean age, 20 yr; SD, 3 yr) consisted of 148 African Americans, 113 European Americans, 133 males, and 128 females, all with a verified family history of CVD (ie, hypertension, myocardial infarction). Anthropometrics, sociometrics, hemodynamics, brachial artery diameter, left ventricular mass, and relative wall thickness were measured and used as independent variables. EDAD (dependent variable) was expressed as percent (%) change of brachial artery diameter to reactive hyperemia induced by pressure cuff occlusion and release. Artery diameters were calculated via an automated border detection system.', 'Percent EDAD change was inversely related to initial diameter of the brachial artery. Mean percent EDAD change was 14.37% for female subjects compared with 10.48% for male subjects. The gender difference was a function of smaller initial artery size in the female subjects. When initial diameter and gender were considered simultaneously within a multivariate model, the gender effect was eliminated. Although a large prediameter effect remained, the relationship between prediameter and EDAD was greater in female than in male subjects (ie, interaction/moderating effect).'] Does gender influence endothelial-dependent arterial dilatation via arterial size in youth?