Perinatal asphyxia is the most important cause of acute neurologic injury in the newborn and occurs in approximately six per 1000 term live births. After resuscitation of an infant with birth asphyxia, the emphasis has been on supportive therapy; however, there is increasing evidence that a "therapeutic window" exists in the early hours following the insult, and perhaps for longer, when intervention can attenuate activation of the neurotoxic cascade that leads to delayed cell death hours, days or months later.