Abstract:Three crystalline components, a new diterpenoid named macrocalyxin G and two known diterpenoids rabdophyllin H and ponicidin, were isolated from the leaves of Rabdosia macrocalyx (Dunn) Hara. Based on spectroscopic and chemical evidence, the structure of macrocalyxin G was established as ent-7β-20-epoxy-6α, 7α, 14α, 15α, 16α-pentahy-drokaurane- 17-acetate.