Regular exercise has blood pressure lowering effects in different types of experimental hypertension models in rats, including nitric oxide synthase (NOS) inhibition model. We aimed to investigate possible mechanisms implicated in exercise effect by evaluating the vasoreactivity of resistance arteries. Exercise effects on agonist-induced vasodilatory responses and flow-mediated dilation were evaluated in vessel segments in rat chronic NOS inhibition model. Normotensive and hypertensive rats were subjected to swimming exercise (1 hour/day, 5 days/week, 6 weeks), while rats in other sedentary and hypertensive groups did not. Hypertension was induced by oral administration of a non-selective NOS inhibitor L-NAME (25 mg/kg day) for 6 weeks. Systolic blood pressure, as measured by the tail-cuff method, was significantly decreased by the training protocol in exercising hypertensive rats. The vasoreactivity of resistance arteries was evaluated by both wire and pressure myography studies. An impaired NO-mediated relaxation pathway in untrained hypertensive rats led to decreased relaxation responses in vessels with intact endothelium. Exercise training significantly improved the responses to acethlycholine and flow-mediated dilation in exercise trained hypertensive rats in parallel with a decrease in blood pressure. On the other hand contraction (norepinephrine and KCl) and relaxation (sodium nitroprusside) responses of vascular smooth muscle were not different between the groups. Vascular eNOS protein expression was found to be increased in both exercising groups. In conclusion, these results revealed an evidence for an increased role of NO-dependent relaxation pathway in exercising hypertensive rats.