Myanesin produces muscle relaxation and reversible paralysis.Small doses of myanesin greatly modify the response to electric stimulation in the rabbit. The convulsive threshold, in rabbits, is raised and the tonic phase eliminated for periods up to an hour. Large doses of electric current are without observed effect if given just as myanesin paralysis sets in. Within 2 minutes after myanesin injection muscular response to strong electric stimulation returns. The margin of safety between a paralyzing dose and a lethal dose is relatively small.In man, myanesin also raises the convulsive threshold to electric shock but moderate doses of myanesin do not prevent a strong, tonic-clonic seizure. Myanesin should be injected intravenously only in l% solution in physiologic saline if hemolysis is to be avoided. Because of its complications, myanesin alone is not recommended for practical use to soften the convulsive rigor in electric shock convulsions in man. Dilantin enhances the ability of myanesin to soften convulsive rigor. The combined use of myanesin and dilantin warrants further trials.