Introduction Previous studies realized by our group showed that a reduction in nitric oxide (NO) bioavailability is associated with a greater platelet activation in hypertension, which may contribute to the higher incidence of thrombotic events of this disease. Aerobic exercise cause important changes in vascular function, which contributes to blood pressure attenuation and hypertension outcomes. The aim of the present paper was to investigate the effects of aerobic training on L-arginine transport and NO synthase (NOS) activity, and also on lipid peroxidation in platelets of spontaneously hypertensive rats (SHR). Methods 16 male SHR and 16 Wistar Kyoto rats (12 weeks old) were divided in two groups each (n=8): exercise (EX) and sedentary (SED). Exercise training was realized on a treadmill (5 d/wk; 60 min/d; velocity progressively increased up to 16 m/s) during 20 weeks. The animals were anesthetized with sodium thiopental (40 mg/kg)injected intraperitoneally and blood was collected from the abdominal aorta. Platelets were obtained by centrifugation and the following experiments were performed: L-arginine transport (by incubation with L-[³H]-arginine), NOS activity (by the conversion of L-[³H]-arginine in L-[³H]-citrulline, and lipid peroxidation (by the production of thiobarbituric acid reactive species, TBARS). SBP was measured weekly by tail cuff plethysmography. Data were compared with a one-way ANOVA, and significance level was set at 5 %. Results SBP was significantly higher in SHR compared to WKY at the baseline (186 ± 8 vs. 132 ± 11 mm Hg). After 20 wk of training, SBP was significantly lower in SHR/EX (138 ± 8 mm Hg) than in SHR/SED (214 ± 9 mm Hg) and SBP did not differ from WKY. There was a significant increase in platelet L-arginine transport (pmol L-arginine/10⁹ cells/min) in both WKY (SED: 0.196 ± 0.054 vs. EX: 0.531 ± 0.052) and SHR (SED: 0.346 ± 0.076 vs. EX: 0.600 ± 0.049). NOS activity (pmol L-citrulline/10⁸ cells) was significantly increased in SHR/EX (0.072 ± 0.007) compared to SHR/SED (0.038 ± 0.007), but no changes were observed in WKY. Exercise did not affect and TBARS production in neither WKY nor SHR group. Conclusion These results confirm the importance of regular aerobic exercise as a non-pharmacological tool in hypertension management. An increase in NO bioavailability, through an upregulation of platelet L-arginine-nitric oxide pathway, may contribute to the hypotensive effect of aerobic exercise training in hypertensive animals.