The syndrome of Malignant Hyperpyrexia in man follows administration of certain general anaesthetic agents, and, although rare, is fatal in 70% of cases (EDITORIAL, 1968). Following exposure to the anaesthetic, there is, in most instances of susceptible individuals, a rapid rise in body temperature, usually within a period of 10 minutes, often accompanied by muscular rigidity of the limbs~ Sometimes hyperthermia has.been delayed for hours and muscular rigidity not pronounced. The temperature reached maybe 43°C (115°F) or even somewhat above this. Halothane, CF3CHBrCl, a ha../o/~nated hydrocarbon, is thought to be responsible for most cases(WILSON, NICHOLS, DENT and ALLEN, 1966). Succinyl choline lfH2COOCH2CH2*(cH3 )~ 201_~H2COOCH2CH2~(cH3 )3 a skeletal muscle relaxant employed during anaesthesia, has also been implicated (BRITT and KALOW, 1970; HARRISON, 1971).