Introduction Since the discovery of the antagonism of bemegride (Megimide; 3-ethyl-3-methylglutarimide; NP13) toward barbiturates (Shaw et al.,271954), a large number of communications have been presented to show the therapeutic value of this substance (Shulman et al.,281955; Shaw,261955; Bentel et al.,31956). As there are still different opinions about the mode of action of the drug, the present investigation was undertaken in order to study the effects with some indices not used earlier. Thus, cerebral blood flow was followed using the new method of Ingvar and Söderberg14(1956), with simultaneous recording of the electroencephalogram (EEG), blood pressure, and cutaneous circulation in narcotized cats and rabbits andencéphale isolépreparations of cats. In a few experiments with cats the gamma motor activity was studied by the method of Granit and Kaada11(1952). In rabbits the antagonism of bemegride toward urethan U. S. P.,