Abstract:Three crystalline components, a new kaurane type diterpenoid named macrocalyxin H and two known diterpenoid oridonin and enmenol, were isolated from the leaves of Rabdosia macrocalyx (Dunn) Hara. Based on IR, MS, 1H-1H COSY, 13C-1H COSY and NOE spectroscopy, the structure of macrocalyxin H was determined as ent-7β-20-epoxy-lα, 6α, 7α, 15α, 16α-pentahydroxy kaurene- 17-acetate.