In this paper, the influences of adrenergic blockades; propranolol and phenoxybenzamine on the changes of hyperglycemic action, hepatic glycogen content, and brain norepinephrine (NE) content induced by clonidine were investigated in the male mice. The results obtained were summarized as follows: 1) Blood glucose level was significantly increased by clonidine (30μg/kg). The increase of blood glucose level induced by clonidine was not affect by the propranolol (10mg/kg) pretreatment, but significantly inhibited by the phenoxybenzamine (10mg/kg) pretreatment. 2) Hepatic glycogen content was moderately inhibited by clonidine. The decrease of hepatic glycogen content induced by clonidine was not affected by the propranolol and phenoxybenzamine pretreatment. 3) Brain NE content was significantly increased in 30 minutes and 60 minutes after clonidine treatment. The increase of brain NE content induced by clonidine was significantly inhibited by the phenoxybenzamine pretreatment. The increase of train NE content induced in 90 minutes and 120 minutes after clonidine treatment was more markedly increased by the propranolol pretreatment.