Experiments were performed on anes-thetized dogs.The vascular resistance of hindlimb was determined by means of constantflow perfusion technique and systemic arte-rial blood pressure was recorded concomitan-tly.An extract from the roots of huang-qiwas injected intravenously or intra-arteriallyin comparison with GABA.The generaof huang-qi of different habitat used in theexperiments were identified as:“Shan-xihuang-qi”and“Gan-su huang-qi”——theroots of Astragalus mongholicus Bunge

“Shan- dong huang-qi”——A.membranaceus（Fisch.）Bunge.Results show that intravenous injec-tion of huang-qi at a dosage of 1.0 gm.perkg.（in terms of the weight of crude drug）causes marked decrease of systemic blood pre-ssure and vascular resistance of hind limb.This effect is considered as a result of di-rect peripheral vasodilatation action and isindependent of its action on the heart.Ascompared with huang-qi

GABA injectedintravenously at a dosage of 10 mg.per kg.（approximated to 30 times of GABA contentin the roots of huang-qi）causes a similarvascular effects

but intra-arterial injectionof small amount of huang-qi（1/25 of in-travenous dose）causes a marked decrease ofvascular resistance of hind limb while GABAdoes not.It seems that GABA cannot repre-sent huang-qi as a whole in respect to itsvascular effect.Results also show that thereare marked difference in the potency of vas-cular action of huang-qi of different habi-tat

but it seems to be no parallel correlationbetween their potency and the content ofGABA.