A comparative study has been made in a group of institutionalized epileptic mental defectives of the anticonvulsant action of dilantin, tridione, and several barbiturate derivatives. The results indicate that dilantin has the most marked anticonvulsant action in most cases, but that maximum action is only achieved with toxic doses in severe cases. Tridione has definite anticonvulsant action against grand mal seizures and is particularly effective in combination with dilantin. Tridione has been successfully used intravenously to terminate status epilepticus and is tolerated in high concentration. Barbiturate derivatives are occasionally effective alone in individual cases but are most effectively used with dilantin.