Background: Aging is associated with an increased risk for atherosclerosis in which endothelial dysfunction is an early marker. Objective: The purpose of this study was to determine if endothelial function is altered with increasing age in healthy subjects. Method: The study population consisted of 30 elderly and 36 younger subjects free from major cardiovascular risk factors. Transthoracic echocardiography was performed for each subject to rule out structural heart disease. Endothelial function was evaluated by flow-mediated dilation (FMD) of the brachial artery via ultrasound. Results: Baseline characteristics of the elderly and the younger group were similar, except for age (mean age: 71.3 +/- 5.8 vs. 26.5 +/- 7.2). Transthoracic echocardiography was normal in all subjects. FMD of the elderly group was significantly lower than the younger group (7.9 +/- 3.1 in the elderly, 10.+/- 8 1.9 in the younger group, p < 0.001). A negative relationship was found between FMD and age (r = -0.528, p < 0.001). Conclusion: It can be concluded that endothelial function detected by FMD declines with increasing age in healthy human subjects. Advanced age is a predictor of impaired endothelial function. Copyright (c) 2008 S. Karger AG, Basel.