Fever is a common reason for parents to bring their child to a phys ician for evaluation. F ever is often treated without regard to its underlying mechanism and potential role in the host response. In fact, fever is a complex dynamic process that is actively regulated by the thermoregulatory center within the central nervous system. In this article, the authors provide an overview of the physiology of thermoregulation, the pathogenesis of fever. and the potential role of fever and the febrile response in limiting infection.