Abstract: AimTo study the chemical constituents of Knoxia valeianoidesThorel et Pitard. MethodsChromatographic methods were used for the isolation and purification. Structures were elucidated on the basis of chemical analysis and spectroscopic data. ResultsThree anthraguinones were isolated from K.valerianoides and identified as 1,3,5-trihydroxy-2-methyl-6-methoxyl-anthraguinone (kaoxiadin, I), 1,3,6-trihydroxy-5-ethoxylmethyl-anthraguinone (II) and 1,3-dihydroxy-2-methyl-anthraguinone (rubiadin, III). ConclusionCompound II is a new anthraguinone constituent.