The term "malignant hyperthermia" (MH), regarded as the typical anaesthetic disease, refers to a clinical syndrome of varying intensity (from abortive courses to fulminant crises) and develops only under exposure of certain triggering substances or mechanisms. MH is caused by a defect in the ryanodine receptor subtype 1, which can often be proved genetically. Furthermore, it may also be generated by other mechanisms which disturb the membranous integrity of skeletal muscle cells (e.g. some myotonias, muscular dystrophies, malformation syndromes). Hyperthermia is only one of a number of life-threatening symptoms that may occur during a fulminant crisis, which ultimately results from an excessive release of calcium into the cytoplasm of muscle cells. Due to a current good knowledge about classical triggers, symptoms and therapeutic interventions, a clinical MH presentation may successfully be treated in the perioperative period. However, it appears to be likely that there are unreported cases outside hospitals since atypical courses or alternative MH triggers (e.g. alcohol, drugs, physical stress) may impair the correct diagnosis. In contrast severe hyperthermia can also arise from other drug-induced diseases, e.g. the neuroleptic malignant syndrome or the serotonin syndrome.