Edaravone is an agent developed as a free radical scavenger, and is useful in functional recovery of the brain after cerebral infarction. However, to the best of our knowledge no experimental studies have been made regarding the effect of edaravone on cerebral protection during aortic arch surgery. We investigated the pharmacological effect of edaravone experimentally, through selective cerebral perfusion under deep hypothermia. Twelve adult dogs (body weight 14.8±2.0 kg) were used, and selective cerebral perfusion was performed under hypothermic circulatory arrest of 20°C for 120 min at 5 mg/kg/min, which was half the usual flow volume of cerebral perfusion. Group E (n=6) received 3 mg/kg edaravone for 30 min at the start of both selective cerebral perfusion and rewarming of the body, while Group C (n=6) received no drugs. Somatosensory evoked potential (SEP) was measured, and so were blood pressure, body temperature, pH level, oxygen partial pressure, and blood flow in the cerebral tissue. Histopathological investigations were also performed. In Group E, complete SEP recovery was observed in all dogs, while in Group C, complete SEP recovery was observed in only 2 dogs (33%) (p=0.014). A statistically significant difference was also observed in cerebral tissue pressure (p=0.014), but not in pH level, oxygen partial pressure, or cerebral tissue blood flow. On histopathological investigation, Group C demonstrated reduced staining of Nissl granules in neurons of the cerebral cortex, and many of them presented the appearance of acute circulatory impairment while Group E demonstrated no reduction in staining of Nissl granules. In the present experimental study of selective cerebral perfusion under deep hypothermia below the safety threshold flow, edaravone was effective in cerebral protection.