Resveratrol is found in a wide variety of plant species. It is present in the seeds and skin of grapes and constitutes one of the major components of red wine. This study was undertaken to evaluate whether resveratrol could effectively suppress infarct size from the damaging effects of focal cerebral ischemia. The middle cerebral artery was occluded for 1 hr and 24 hr reperfusion in anesthetized Long-Evans rats. In pretreatment or treatment groups, resveratrol, at dosages of 10(-6), 10(-7), 10(-8) and 10(-9) g/kg, was intravenous injected 15 minutes before middle cerebral artery (MCA) occlusion or when the common carotid arteries clips were removed respectively. Pretreatment or treatment of resveratrol (10(-6), 10(-7), 10(-8) and 10(-9) g/kg) did not produce any changes in pH, blood gases, heart rate or mean arterial blood pressure, but it significantly reduced the total volume of infarction at the doses 10(-6) and 10(-7) g/kg. Our study suggests resveratrol is a potent neuroprotective agent in focal cerebral ischemia. Its beneficial effects may be related to its anti-platelet aggregation activity, vasodilating effect, antioxidant property or by all mechanisms together.