Investigation on the mono-, di-, and trihydroxy triterpenoid constituents in the flower extracts from various Compositae plants has led to the isolation and identification of ψ-taraxasterol, taraxasterol, β-amyrin, α-amyrin, helianol, and seven other monohydroxy triterpenoids, and faradiol, arnidiol, and eleven other di- and trihydroxy triterpenoids. Although ψ-taraxasterol, taraxasterol, β-amyrin, and α-amyrin, constituted the major components for some species, helianol, a 3,4-seco-triterpene alcohol, was the most abundant in the monohydroxy triterpenoid fractions from the tabular flowers of some species. On the other hand, either one of the two dihydroxy taraxeranes, faradiol and arnidiol, constituted the most predominant component in the di- and trihydroxy triterpenoid fractions from most of the species examined. These triterpenoids were evaluated with respect to their anti-inflammatory activity against 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation in mice. All of these showed marked inhibitory activity, and their 50% inhibitory dose was 0.03-0.8 mg per ear. Because the inhibitory effects against TPA-induced inflammation have been demonstrated to closely parallel those against tumor-promotion, and because the Compositae flowers, thus, contain the triterpenoids possessing strong anti-inflammatory activity, the extracts of Compositae flowers and the triterpenoids therefrom may be of importance from the viewpoint of chemoprevention of cancer.