A new triterpene, terebinthone, has been isolated from the berries of Schinus terebinthefolius (Radd.). Analyses indicate the formula C30H46O3. Spectral evidence indicates that the compound is a diketone with one group in the C-3 position and the second in a highly hindered position. Reduction and hydrogenation studies supported these findings. Ozonolysis produced acetaldehyde showing that the single double bond is in the side chain as an ethylidene group. The third oxygen of terebinthone is believed to be in a cyclic ether ring.