Trichostemonoate (1), a new tirucallane, together with four known compounds, 11α,20-dihydroxydammar-24-ene-3-one (2), sapelin E acetate (3), grandifolinolenenone (4) and α-mangostin (5), were isolated from the stem bark of Walsura trichostemon. The structural assignment of the new compound was based