Oxidative stress is one of the major pathological factors in the cascade that leads to cell death in cerebral ischemia. Here, we investigated the neuroprotective effect of a naturally occurring antioxidant, oxyresveratrol, to reduce brain injury after cerebral stroke. We used the transient rat middle cerebral artery occlusion (MCAO) model of brain ischemia to induce a defined brain infarction. Oxyresveratrol was given twice intraperitoneally: immediately after occlusion and at the time of reperfusion. Oxyresveratrol (10 or 20 mg/kg) significantly reduced the brain infarct volume by approximately 54% and 63%, respectively, when compared to vehicle-treated MCAO rats. Also, the neurological deficits as assessed by different scoring methods improved in oxyresveratrol-treated MCAO rats. Histological analysis of apoptotic markers in the ischemic brain area revealed that oxyresveratrol treatment diminished cytochrome c release and decreased caspase-3 activation in MCAO rats. Also, staining for apoptotic DNA showed that the number of apoptotic nuclei in ischemic brain was reduced after oxyresveratrol treatment as compared to the vehicle-treated MCAO rats. This dose-dependent neuroprotective effect of oxyresveratrol in an in vivo stroke model demonstrates that this drug may prove to be beneficial for a therapeutic strategy to limit brain injury in acute brain ischemia. © 2004 Elsevier B.V. All rights reserved.