Objectives: The present study aimed to assess the effect of acute exhaustive training (AE) on microvascular reactivity and endothelial function of the skin microcirculation in professional rowers and sedentary subjects, as well as to determine the possible role of changed hemodynamic and/or oxidative stress level in the regulation of skin microvascular blood flow after AE in these subjects. Study Design: Experimental research with nonrandomized pretest-posttest control group design. Participants and Methods: Anthropometric measures, body composition, biochemical and hemodynamic parameters were measured in eighteen young healthy sedentary men (Sedentary) and twenty professional rowers (Rowers) who underwent a single acute exercise session. All subjects underwent a single progressive rowing training to maximal exhaustion. Blood lactate levels, as well as arterial blood gas analysis and acid base status were measured before and after AE. Cutaneous microvascular blood flow measurements were done by Laser Doppler Flowmetry in response to vascular occlusion (post occlusive reactive hyperemic - PORH) and in response to iontophoresis of acetylcholine (ACh% dilation) (endothelium-dependent vasodilation), and sodium nitroprusside (SNP% dilation) (endothelium-independent vasodilation), before and after AE. Serum lipid peroxidation products (oxidative stress) and plasma antioxidant capacity were measured in both study groups before and after AE, using spectrophotometric methods. Results: All subjects were normotensive, lean, age-matched males, with similar anthropometric measures and body composition. Rowers had lower trygicerides and apolipoprotein B, and higher HDL cholesterol level compared to Sedentary. All subjects were normotensive at baseline, but Rowers had significantly lower diastolic (DBP), and mean arterial pressure (MAP) and heart rate (HR), and higher stroke volume (SV) than Sedentary. Rowers had significantly better PORH and endothelium-dependent vasodilation than Sedentary at baseline. Serum lactate, glucose, and hsCRP significantly increased and metabolic acidosis occurred after AE in both Sedentary and Rowers, which confirms that AE protocol led all subjects from both experimantal groups to complete exhaustion. AE caused a significant increase in systolic blood pressure, DBP, HR and SV, and a decrease in total peripheral resistance in both groups. AE caused significant impairment in PORH and ACh-induced dilation in Rowers, while it improved ACh-induced dilation in Sedentary. AE did not induce significant change in SNP-induced in any expmerimental group. Plasma antioxidant capacity significantly increased only in Sedentary after AE. Conslusion: Regular exercise reduces traditional CV risk factors, and has a benefitial effect on vascular health and skin microvascular endothelial function even in young healthy subjects. A single progressive rowing session to maximal exhaustion impaired microvascular reactivity and endothelial function in trained rowers, but not in sedentary subjects, possibly due to: 1) more rowing stages and higher exercise intensity achieved by rowers, and/or 2) higher transient increase in systolic blood pressure that occurred in rowers, compared to sedentary subjects. Key words: acute exercise; endothelium; hemodynamics; microvascular reactivity; oxidative