In this study, the cardioprotective effects of the NO-Aspirin, the nitro-derivative of aspirin, were compared with that of aspirin in an anesthetized rat model of myocardial ischemia/reperfusion. Rats were given aspirin or NO-Aspirin orally for 7 consecutive days prior to 25 min of myocardial ischemia followed by 48 h of reperfusion (MI/R). Treatment groups included vehicle (Tween 80), aspirin (30mg/kg/day) and NO-Aspirin (56 mg/kg/day). NO-Aspirin, compared to aspirin, displayed remarkable cardioprotection in rats subjected to MI/R by the mortality rate and infarct size. Mortality rate for vehicle (n=23), aspirin (n=22) and NO-Aspirin groups (n=22) were 34.8%, 27.3% and 18.2%, respectively. Infarct size of the vehicle group was 44.5± 2.7% of the left ventricle (LV). In contrast, infarct size of the LV decreased in the aspirin and NO-Aspirin pretreated groups, 36.7±1.8% and 22.9 ± 4.3% respectively (both p < 0.05 compared with vehicle group, and p < 0.05 when NO-Aspirin vs. aspirin ) respectively. Moreover, NO-Aspirin also improved ischemia/reperfusion-induced myocardial contractile dysfunction on post-ischemic left ventricular developed pressure. In addition, NO-Aspirin downregulated iNOS (0.37 fold, p<0.01) and COX-2 (0.61 fold, p<0.05) genes expression compared to the vehicle group after 48 h reperfusion. Treatment with N^G-nitro-L-arginine methyl ester (L-NAME, 20mg/kg), a non-selective NOS inhibitor, aggravated myocardial damage in terms of mortality and infarct size, but attenuated in co-administered with NO-Aspirin. L-NAME administration did not alter the increase in iNOS and COX-2 expression but did reverse the NO-Aspirin-induced inhibition of expression of the two genes. The beneficial effects of NO-Aspirin appeared to be derived largely from NO moiety which attenuated myocardial injury to limit infarct size and better recovery of LV function following ischemia and reperfusion.