The pharmacogenetic syndrome of malignant hyperthermia (MH) in response to general anaesthesia, though rare, is usually fatal when it does occur. A case of anaesthetic-induced MH arising in a 10-year-old girl during intranasal antrostomy and successfully treated with dantrolene sodium (Dantrium; SKF) is described. A treatment protocol for MH is appended. The importance of an awareness on the part of the clinician together with prompt reaction to early tell-tale signs is stressed.