Postconditioning, i.e., brief intermittent episodes of myocardial ischemia-reperfusion performed at the onset of reperfusion, reduces infarct size following prolonged ischemia. Our goal was to determine whether postconditioning is protective against myocardial stunning. Accordingly, conscious chronically instrumented dogs (sonomicrometry, coronary balloon occluder) were subjected to a control sequence (10 min coronary artery occlusion, CAO, followed by coronary artery reperfusion, CAR) and a week apart to postconditioning with 4 cycles of brief CAR and CAO performed at completion of the 10 min-CAO. Three postconditioning protocols were investigated, i.e., 15 s-CAR/15 s-CAO (n=5), 30 s-CAR/30 s-CAO (n=7) and 1 min-CAR/1 min-CAO (n=6). Left ventricular wall thickening was abolished during CAO and similarly reduced during subsequent stunning in control and postconditioning sequences (e.g. at 1 h-CAR, 33±4% vs 34±4%, 30±4% vs 30±4%, 33±4% vs 32±4% for postconditioning-15 s, postconditioning-30 s, postconditioning-1 min vs corresponding control, respectively). We confirmed this result in anesthetized rabbits by demonstrating that shortening of left ventricular segment length was similarly depressed following 10 min-CAO in control and postconditioning sequences (4 cycles of 30 s-CAR/ 30 s-CAO). In additional rabbits, the same postconditioning protocol significantly reduced infarct size following 30 min-CAO and 3 h-CAR (39±7%, n=6 vs 56±4%, n=7 of the area at risk in postconditioning vs control, respectively). Thus, contrasting to its beneficial effects on myocardial infarction, postconditioning does not protect against myocardial stunning in dogs and rabbits. Conversely, additional episodes of ischemia-reperfusion with postconditioning do not worsen myocardial stunning.