In mice and rats, a subcutaneous injection of glucose, or of glucose plus insulin, did not ameliorate the symptoms resulting from subsequent subcutaneous injection of either alkali or methyl cyanides, or from the inhalation of gaseous HCN. Under the same experimental conditions, glucosone, though less efficient than cystine, exerted a definite antagonistic action towards cyanides. Though somewhat variable results were obtained with rabbits, glucosone or glucose plus insulin injected intravenously seems to be protective against the intravenous administration of alkali cyanide.