4-N-Alkylamino derivatives and corresponding ammonium quaternary salts of tetrahydro-1,4-benzodiazepin-5-one were synthesized and evaluated for psychotropic activity in mice by ip via. This study was also extended to some nitro and amino derivatives of tetrahydro-1,4-benzodiazepin-5-one. Compounds were devoid of tranquilizing activity and in comparison with two classical benzodiazepines, chlordiazepoxide and diazepam, they showed high toxicity and little or no effect on motor coordination, motor activity, and maximal electroshock. On some "in vitro" tests the compounds exhibited pharmacological properties when they were used at high concentrations.