Symptoms and signs of impaired thermal homeostasis are protean. Clinical encounters with the geriatric patient, whether acute or chronic, are often marked by imprecise historical detail, ambiguous physical findings, differing laboratory values, and unexpected responses to therapeutic modalities. In addition, geriatric patients presenting with disorders of thermoregulation have a greater morbidity and mortality than other groups. This article briefly reviews thermoregulation as well as some of the causes and treatments for both hypothermia and hyperthermia.