A series of N-substituted 1-(4'-aminophenyl)-4-methyl-3,4-dihydro-7,8-methylenedioxy-5H-2,3-benzodiazepines, structural analogues of the selective non-NMDA antagonist GYKI 52466, has been synthesized and tested for biological activity in vivo and in vitro. GYKI 52466 (1) is a 2,3-benzodiazepine compound with muscle relaxant and anticonvulsant potencies3. It has been reported that this drug inhibits neuronal responses mediated by the non-NMDA type glutamate receptors in neocortical neurons in vitro4, in abducens motoneurons in vivo5, and in various seizure models3,6. Non-NMDA receptors seem to be involved in certain neurodegenerative disorders, suggesting a possible therapeutic application for their antagonists as neuroprotective drugs7. GYKI 52466 has been shown to protect animals from ischaemic brain damage8 and hippocampal neurons from the toxic action of the non-NMDA agonist kainate applied in local injection9 as well. In the present study, several structural analogues of GYKI 52466 have been prepared and evaluated in order to develop new compounds with similar but stronger pharmacological actions. The structure-activity relationships were investigated in vivo and in vitro as well. The first results of this study are presented here.