Numerous homeostatic and regulatory control mechanisms act to balance body heat production and dissipation. Hyperthermia occurs when heat production exceeds the body's ability to lose heat or energy. Although the pathogenesis of hyperthermia varies among different etiologies, the complications are similar: rhabdomyolysis, disseminated intravascular coagulation, hyperkalemia, renal failure, metabolic acidosis, liver failure, and death. This article discusses four relatively common syndromes as examples of drug-induced hyperthermia: (1) familial malignant hyperthermia (MH), (2) neuroleptic malignant syndrome (NMS), (3) sympathomimetic poisoning, and (4) anticholinergic poisoning syndrome.