Foliar flavonoids of Crossostephium chinense in Japan and Taiwan were isolated and further characterized. Eighteen flavonoid aglycones, luteolin, apigenin, hispidulin, chrysoeriol, 5,7,4'-trihydroxy-6,3',5'-trimethoxyflavone, jaceosidin, cilsimaritin, quercetin 3-methyl ether, axillarin, chrysosplenol-D, cirsiliol, apometzgerin, 5,7,3'-trihydroxy-6,4',5'-trimethoxyflavone, luteolin 3',4'-dimethyl ether, cirsilineol, eupatilin, nepetin and 5,7,3',4'-tetrahydroxy-6,5'-dimethoxyflavone, were identified by UV, 1H and 13C NMR spectroscopic, LC-MS and HPLC comparisons w ith authentic samples. The compounds existed on the leaf surface. Four flavonoid glycosides, quercetin 3,7-di-O-glucoside, quercetin 3-O-rutinoside, luteolin 7-O-glucoside and apigenin 7-O-rutinoside, were also isolated as the intracellular flavonoids. It was shown by HPLC survey that variation of the species' flavonoids occurs among the collection sites.