BACKGROUND: Increased arterial stiffness is an accepted cardiovascular risk factor. Several studies have shown that regular exercise is associated with reduced arterial stiffness. However, the acute effect is not well known. The aim of this study was to evaluate the acute impact of exercise on arterial stiffness measured by pulse wave velocity (PWV). METHODS: One hundred men (age 53 짹 13 years, 60 male, 40 female) underwent measures of brachial-ankle pulse wave velocity (baPWV) before and after a graded maximal aerobic exercise test. Four extremity blood pressures and bilateral ankle brachial index (ABI) were also measured before and after the exercise test. RESULTS AND CONCLUSION: Upper extremity systolic blood pressure did not change from baseline. However, upper extremity diastolic blood pressure increased slightly. In addition, lower extremity blood pressure decreased in both systolic and diastolic phases. With respect to baPWV, it decreased after the exercise test (before vs. after; 1420 짹 260 vs. 1358 짹 245, 1428 짹 255, vs. 1360 짹 239 cm s(-1); left and right, respectively). Moreover, ABI decreased after the exercise test (1.11 짹 0.06 vs. 1.05 짹 0.08, 1.12 짹 0.06, vs. 1.06 짹 0.08 ; left and right, respectively). These results suggest that exercise acutely decreases arterial stiffness.