Objective To investigate the protective action of oxygen-breathing pretreatment against brain ischemia-reperfusion injury in rats. Methods Using a model of focal brain ischemia-reperfusion in Sprague-Dowley rats, SOD activity and MDA level measurement, electron microscopy and neurological functional examination were performed to evaluate the protective role of oxygen-breathing pretreatment. Results Oxygen-breathing pretreatment showed a protective effect on brain ischemia-reperfusion injury. It presented significantly increased SOD level and decreased content of MDA. The ultrastructure of neurons in rats of oxygen-breathing pretreated group was ameliorated effectively. Conclusions Oxygen-breathing pretreatment has protective effect against brain ischemia-reperfusion injury.