From the underground parts of Pertya robusta (Compositae) were isolated O-methyl pertyol (I) and a new tetracylic triterpene methyl ether (III), C₃₂H₅₄O, mp 162-162.5°, [α] D+84°, in addition to bauerenyl acetate (X), friedelin (XI), and friedelan-3β-ol (XII). The structure of III was established to be (24S) 3β-methoxy-24-methyllanosta-9 (11), 25-diene by synthesis of the dihydro derivative of III from 24-methylenecycloartanol. Distribution of triterpene components (I, III, X, XI, XII and taraxeryl acetate (XIII)) was investigated from the chemotaxonomic standpoint of Pertya spp.