The authors submit the case-history of a 29-year-old man, followed up on account of liver steatosis with a toxic-nutritional etiology who developed, after previous increased physical exertion and alcohol abuse, fever associated with major muscular weakness. Gradually he developed an amental delirious state which was evaluated as suspect delirium tremens. Fever of 40-41 degrees C continued, the patient developed muscular rigidity, tremor and hypotension. After intubation during which succinylcholine was administered, the patient's condition deteriorated further with a rise of temperature and muscular rigidity. The patient developed acute renal failure with anuria and the necessity of repeated haemodialyses and severe acidosis of the mixed type on account of which he was intubated and switched to artificial ventilation. According to the case-history clinical and laboratory picture of the disease (extremely high creatine kinase activity, hyperkalaemia, acidosis, hepatorenal failure) malignant hyperthermia was suspected. After a single intravenous injection of sodium dantrolene, 2.5 mg/kg, the temperature dropped and within 24 hours the patient was afebrile. Gradually the acidosis improved, the blood pressure became stabilized and artificial ventilation was no longer used. The patient was discharged after 34 days in hospital in a state of cardiopulmonary compensation with mild polyuria but without signs of retention of nitrogenous substances with sideropenic anaemia and marginal creatine kinase and lactate dehydrogenase values. Within one month after discharge the laboratory values reached normal levels and only slight muscular weakness and greater fatiguability persisted.