Abstract
The members of a family in whom three malignant hyperpyrexial deaths occurred during anaesthesia were studied by means of serum creatine phosphokinase estimations. Abnormally high levels were found in many asymptomatic relatives. It is suggested that the abnormal levels reflect a subclinical myopathy of autosomal dominant inheritance which possesses a potentially lethal propensity resulting in a malignant hyperpyrexia when challenged with various anaesthetic agents. Possibly sudden unexplained deaths under varying circumstances are a further expression of this underlying abnormality.A possible clue to the anticipation of future cases of malignant hyperpyrexia has been found, and it is suggested that relatives of previous cases be investigated.