Important differences exist between adult and newborn responses to different cerebrovascular influences. This review discusses the important influence that the prostanoid system has in newborn cerebral hemodynamics. Activated oxygen species and their generation through different cerebral insults are discussed. The role of several radical scavengers as modes of therapy is reviewed. The endo-thelium-derived relaxing factor system and its major influence in the adult is compared with its lesser role in the newborn. Finally, the pathophysiology of the alterations in newborn cerebral hemodynamics seen with experimentally induced seizures is reviewed.