Abstract: Pharmacological effects of Tibetan medical plant Artemisia sieversiana on the hypothalamo-pituitary-adrenocortical axis are reported in present paper.The alcoholic (60%) extract of A. sieversiana (AEAS) injected intraperitoneally at 460 mg/kg in rats enhanced significantly the levels of corticosterone of the peripheral and adrenal venous plasma from 41±1.8 to 78±2.1 μg/100ml and from 1220±64 to 2020±56μg/ml (mean+SE) respectively. Administrations of AEAS at 3 g/kg orally or 460 mg/kg/day ip (for 6 days) also produced a marked increase. However, the increase was not detected in hypophysectomized rats. The effect of AEAS could be blocked completely by morphine in combination with pentobarbital, but not by pentobarbital alone, nor by prior injection of dexamethasone, chlorpromazine or cortisone acetate in rats under pentobarbital sodium anesthesia.We also demonstrated that in the same doses AEAS (ip) markedly increased the 5-HT content in the diencephalon of rats but not the 5-HIAA and NE contents. The action of AEAS which had been shown to result in the activation of the pituitary-adrenocortical system, was not abolished by prior treatment with reserpine at 4 mg/kg, but was completly blocked by the injection of atropine (250 μg) into the lateral ventricle of the brain. In intact rats AEAS produced a decrease of the amount of GABA in the diencephalon and significant increase of glutamine levels, while in adrenolectomized rats the effects were reversed.It is considered that the antiphlogistic effects of AEAS are due to its activation of ACh and 5-HT system and inhibition of GABA in the hypothalamus. Through the regulative action of the neurotransmitters, CRF is further activated, and, finally, it leads to the serial response of the pituitary-adrenocortical system.