Abstract: Three diterpenoids have been isolated from the dried leaves and stems of Rabclosia rosthornii (Diels) Hara. Two of them were shown to be known diterpenoids, ponicidin and oridonin, while the third one, a new kaurenetype diterpene, was named rosthorin A. The structure of the new compound was identified as ent-6β, 7β, 11β, 14β-tetrahydroxy-7, 20-epoxy-16-kauren-15-one., on basis of physico-chemical constants, spectroscopic analyses and properties of derivatives.