The present study sought to determine whether the combination of late preconditioning with postconditioning enhances the reduction in infarct size. Methods: Chronically instrumented rats were assigned to a 45-min (Subset 1) or 60-min (Subset 2) coronary occlusion followed by 24 h of reperfusion. In each subset, rats received no further intervention (control), were preconditioned 24 h before occlusion (PC), postconditioned at the onset of reperfusion following occlusion, or pre- and postconditioned without (PC + postconditioning) or with the COX-2 inhibitor celecoxib (3 mg/kg, ip; PC + postconditioning + celecoxib) 10 min before postconditioning. Myocardial COX-2 protein expression and COX-2 activity (assessed as myocardial levels of prostaglandin E2 [PGE2]) were measured 6 min after reperfusion in an additional five groups (control, PC, postconditioning, PC + postconditioning, and PC + postconditioning + celecoxib) subjected to a 45-min occlusion. Results: PC alone reduced infarct size after a 45-min but not a 60-min occlusion. Postconditioning alone did not reduce infarct size in either setting. However, the combination of late preconditioning and postconditioning resulted in a robust infarct-sparing effect in both settings, suggesting additive cardioprotection. Celecoxib completely abrogated the infarct-sparing effect of the combined interventions in both settings. Late PC increased COX-2 protein expression and PGE2 content. PGE2 content (but not COX-2 protein) was further increased by the combination of both interventions, suggesting that postconditioning increases the activity of COX-2 induced by late PC. Conclusions: the combination of late PC and postconditioning produces additive protection, likely due to a postconditioning-induced enhancement of COX-2 activity.