It is well known that picrotoxin, an amaroid substance of Anamirta cocculus, is a classic stimulant on the central nervous system accompanying convulsive activity, and it liberates catecholameine from the adrenal mdulla through its central action to increase blood sugar level. Schou reported that lithium and alcohol have the similar inhibitory property on the Na⁺, K⁺-ATPase activity, and recently, the therapeutic efficacies of lithium on the alcohol withdrawal syndrome and the chronic alcoholics have been studied. Many studies about the hypoglycemic effect of lithium and alcohol were reported but the interaction between those hypoglycemic action is little known. Therefore, in this paper, the hypoglycemic effect of lithium and ethanol on the hyperglycemia induced with picrotoxin, and the interaction of them in those hypoglycemic action were investigated with reference to the anticonvulsive action of them. The results were obtained as follows: 1. The convulsive dose (CD₅₀) of picrotoxin in mice was slightly increased by the pretreatment of lithium or ethanol. 2. The blood sugar level was markedly increased by picrotoxin but the level was sugar level was significantly decreased by lithium, ethanol or both. 3. The hyperglycemic effect of picrotoxin was significantly potentiated by the lithium pretreatment, but the potentiation effect of lithium was markedly suppressed by the additional injection of ethanol after lithium injection and more markedly suppressed by the premedication of ethanol before lithium injection 4. The hyperglycemic effect of picrotoxin was markedly inhibited by the ethanol pretreatment, and the inhibitory effect of ethanol was significantly strenthened by the additional injection of lithium after ethanol injection, but on the contrary, the inhibitory effect was completely disappeared by the premedication of lithium before ethanol injection.