Malignant hyperthermia is a potentially fatal hypermetabolic syndrome characterized by hyperpyr-exia and skeletal muscle rigidity. It can be induced by all of the currently used inhalation anesthetics or by injection of succinylcholine. This case is presented of a 32 year old healthy male patient in whom a orthopedic operation was performed under O2-N2O-enflurane anesthesia with induction by pentothal sodium and succinylcholine. One hour after induction, tachycardia developed and was followed by unstable blood pressure, hyperpyrexia, arrhythmia and muscle rigidity. Anesthesia was terminated and vigorous emergency treatment was attempted. But the patient died about 4 hours after induction of anesthesia. The etiologic factors, clinical feature, treatment and prevention of malignant hyperthermia are discussed.