Malignant hyperthermia (MH) is a rare, often life-threatening complication of general anaesthesia. The timely diagnosis of an MH crisis in onset, as a prerequisite for successful therapy, can be difficult for the anaesthetist because of the few and non-specific early symptoms. This is even more so in patients in whom anaesthesia with MH trigger substances has already been performed in the past without any particular complications so leading to a false sense of security with regard to MH sensitivity. The case presented is a healthy young man with a congenital cleft lip, jaw and palette who developed a fulminant MH crisis during his ninth general anaesthesia. Post-operative research into the course of the previous anaesthesias revealed signs of MH crises which however proceeded abortively and were therefore unnoticed. In the case presented, the diagnosis was additionally complicated by the untypical course of the early symptoms. Tachycardia which in 80 % of cases is described as the first symptom of an MH crisis in onset, was at first completely absent and was only moderately pronounced in the full clinical picture of MH. On the other hand, a steady increase in body temperature, a cardinal symptom which usually appears later, was registered early. The suspected diagnosis of MH was then finally confirmed in the fourth hour after start of anaesthesia on the basis of the repeatedly increased end expiratory CO(2) levels. These could not otherwise be explained although several respiratory corrections were performed. Despite immediate MH specific therapy, the crisis developed in the following hour into the full clinical picture: maximum temperature of 41.4 degrees C, end expiratory CO(2) 100mm Hg, consumptive coagulopathy, acute renal failure and shock (systolic blood pressure < 50mm Hg, heart rate 115/minute). After 2 hours of specific intensive therapy, the patient was finally stabilized and transfer to the intensive care unit was possible. 24 hours after the event, the patient was could be extubated without any complications and 2 days later, he was transferred to the normal ward. The intra-operative diagnosis of MH was confirmed 3 days later by means of genetic analysis. Two mutations of the RYR1 gene were identified.