Myocardial ischemia-reperfusion (MI/R) may induce renal damage. A rat model of M/IR injury was established. The left coronary artery was clamped for 30 min, constituting the ischemic period, and was then released for 120 min, thus constituting the reperfusion period. The purpose of this study was to evaluate the effects of caffeic acid phenethyl ester (CAPE), an antioxidant, on renal dysfunction in rats undergoing MI/R. CAPE (50 mu mol/kg) was administered by infusion 10 min before ischemia and during occlusion. Hemodynamic changes were recorded during the different periods. At the end of the reperfusion period, rats were sacrificed, and the kidneys were quickly removed for biochemical determination and histopathological analysis. MI/R was accompanied by a significant increase in malondialdehyde (MDA) production and decrease in glutathione (GSH) content in the rat kidney. Administration of CAPE reduced MDA production and prevented depletion of GSH content. These beneficial changes in these biochemical parameters were also associated with parallel changes in histopathological appearance. These findings imply that MI/R plays a causal role in kidney injury through overproduction of oxygen radicals or insufficient antioxidant, and CAPE exerts renal-protective effects probably by its radical scavenging and antioxidant activities.