A new taxane diterpenoid with a rearranged 5/7/6-membered ring system was isolated from the seeds of the Chinese yew, Taxus yunnanensis. Its structure was established as 9α-acetoxy-5α-cinnamoyl-11(15→ 1)-abeotaxa-4(20), 11-diene-10β, 13α, 15-triol on the basis of spectroscopic analysis. Its relative stereochemistry is proposed from the results of a NOESY experment.