Gan-Cao(Glycyrrhiza uralrrnsis Fisch),a famous Chinese traditional medicinal herb,is generally used in our country as an antitoaio,antitnssive and expectorant agent.Six different species of Glycyrrhiza are available in China antiussive all are spited for medicinal use.Among which the roots of Glycyrrhiza vrcflatd Bat,natively grown in Autonomous Region Xin jiang,has the finest quality and thus attracted our attention to study its chemical constituents.A new type of chaloone(1),named licochaloone,was isolated from its chloroform extract followed by chromatography successively on polyamide and aluminum oxide columns.Its structure was elucidated as 2-methoxy-4,4'-dihydrogy-5-α,α-dimethyl allyl chaloone(1) by alkaline degradation,spectral analyses and total synthesis.