Although hypothermia is most common in patients who are exposed to a cold environment, it can develop secondary to toxin exposure, metabolic derangements, infections, and dysfunction of the central nervous and endocrine systems. The clinical presentation of hypothermia includes a spectrum of symptoms and is grouped into the following three categories: mild, moderate, and severe. Management depends on the degree of hypothermia present. Treatment modalities range from noninvasive, passive external warming techniques (e.g., removal of cold, wet clothing; movement to a warm environment) to active external rewarming (e.g., insulation with warm blankets) to active core rewarming (e.g., warmed intravenous fluid infusions, heated humidified oxygen, body cavity lavage, and extracorporeal blood warming). Mild to moderate hypothermia is treated easily with supportive care in most clinical settings and has good patient outcomes. The treatment of severe hypothermia is more complex, and outcomes depend heavily on clinical resources. Prevention and recognition of atypical presentations are essential to reducing the rates of morbidity and mortality associated with this condition.