Endothelial function was evaluated in 34 young men and women with a family history of premature coronary artery disease (CAD) and 28 control subjects. Men with a family history of CAD had significantly impaired flow-mediated, endothelium-dependent vasodilation of the brachial artery compared with controls; however, in women, there was no difference in flow-mediated vasodilation between subjects with a family history and controls.