The present work examined whether polymorphonuclear neutrophil (PMN) infiltration contributes to cortical and striatal brain damage and oxidative stress in a model of transient focal cerebral ischemia. A 2-h occlusion of the left middle cerebral artery and ipsilateral common carotid artery was performed in rats. Administration of the neutropenic agent vinblastine (0.5 mg/kg, i.v.) resulted in a profound decrease in circulating PMNs which was associated with a 80% decrease in myeloperoxidase activity, a marker of PMN infiltration, in both the cortex and the striatum. In the cortex, vinblastine-treated animals exhibited a 44% decrease in the infarct volume and also reduced the oxidative stress (evaluated by the decrease in glutathione concentrations). By contrast, in the striatum, neutropenia modified neither the lesion size nor the oxidative stress. These results indicate that PMN contribution to postischemic injury and oxidative stress is dependent on the brain structure.