Abstract The essential oils of the aerial parts of Baccharis spartioides (Hook, et Arn.) Remy (Compositae) from three different Patagonian populations were obtained by hydrodistillation and analyzed by capillary GC and GC/M S. Fifty-four components, representing approximately 84.6â97.4% of the oil samples, were identified. The samples consisted mainly of hydrocarbons and oxygenated monoterpenes. The major constituents were limonene (28.7â56.7%), 6R-7R-bisabolone (3.2â9.1%), sabinene (0.1â11.0%) and citronellal (2.4â5.2%).