Abstract: The structure of henryin, a new diterpenoid isolated from the dried leaves of Rabdosia henryi (Hemsl.) Hara, has been determined as (I ) on the basis of spectral and chemical evidence. Two known diterpenoids, kame- bakaurin (I ) and kamebacetal A (Ⅲ) were also isolated together with anotber new diterpenoid which will be published elsewhere. Based on the preliminary antitumoactivity test, compounds of (Ⅰ), (Ⅱ) and (Ⅲ) show a definite cytotoxic effect against Ehrlich carsinoma cells in vi-tro.

Key words: structure, henryin