Introduction: Many studies have used Flow-mediated dilation (FMD) as a prognostic marker for cardiovascular events. Most studies of this kind have been performed on high-risk patient groups. It is known that local endothelial function can be altered by influence of aerobic exercise. The purpose of this study was to investigate how endothelial function, measured by brachial artery flow-mediated vasodilation, would compare a group of male top-level endurance athletes to healthy untrained adult men. Methods: In this study 11 elite rowing athletes and 10 healthy untrained age matched controls were selected. Diameter and blood flow of the brachial artery were recorded using Doppler ultrasound at rest and following 5 minutes of occlusion. A forearm arterial occluding cuff were used to induce reactive hyperemia, thereby causing a flow mediated dilation in the brachial artery. Results: At both rest and during reactive hyperemia blood flow through and diameter across the brachial artery were significantly higher (p<0.001) in the rowing group compared to that of the controls (blood flowing at 128 ± 44 vs 77 ± 31 at rest and 897 ± 202 vs 557 ± 149 mL/min at peak and diameter measuring 5.09 ± 0.40 vs 3.98 ± 0.30 at rest and 5.39 ± 0.41 vs 4.26 ±0.37 mm at peak). Flow-mediated dilation showed no significant difference between the athletes and the controls (5.6 ± 2.6 vs 7.0 ± 2.4 % p=0.2). Discussion: Despite the differences in local blood flow and diameter of the brachial artery there were found no significant differences in the flow-mediated dilation between the two groups. The athletes had larger arteries, but still had the same ability to make relative changes of its diameter.