Patients with central nervous system trauma frequently have fevers while in the neurosurgical intensive care unit. Temperature elevations in the neurosurgical patient often cause much diagnostic confusion, and little is written that assists the critical care team in arriving at a proper etiologic diagnosis for the fever. This article discusses the common causes of temperature elevations in neurosurgical patients, such as central fever, wound infection, nosocomial pneumonia, posterior fossa syndrome, line sepsis, urosepsis, and drug fever. The recognition of central fevers, posterior fossa syndrome, and drug fevers is particularly important in neurosurgical patients to avoid inappropriate and potentially dangerous treatment with unnecessary antimicrobial therapy. Clinical and laboratory clues provide the clinician with a diagnostic approach to fever in the neurosurgical intensive care setting.