In the sense that the brain houses the central mechanism for the regulation of body temperature, almost all illnesses that cause fever must interact with the central nervous system. There are far fewer diseases, however, in which the nervous system symptomatology is of prime diagnostic importance. A helpful way to view fever in association with neurologic disease is to roughly divide these disease entities into four broad categories: (1) neurologic impairment resulting from fever itself, (2) fever as the sole manifestation of a central nervous system infection, (3) systemic febrile disorders with central nervous system signs and symptoms, and (4) primary neurologic diseases, either central or peripheral in origin, with fever as a presenting sign. This article discusses the clinical presentation of disorders in each of these categories as an aid to the clinician in diagnosing and differentiating between these syndromes.