AbstractThe aerial parts of wild Achillea wilhelmsiiC. Koch and A. kellalensisBoiss. & Hausskn. (Asteraceae family) were collected from Southwestern Iran provinces. The essential oils obtained by steam distillation from fine powder of the leaves and flowers of the two Achilleaspecies have been analyzed by GC and GC-MS. The oil yield varied of 0.23 to 0.68% dry matter. The variations in chemical compositions from the flowers and leaves are important between plant populations. A total of 46 constituents were identified. The major constituents of the essential oils of A. wilhelmsiicollected from the Ben and Natanz regions were lavandulyl acetate (t 26.2%), chrysanthenone (t 18.3%), 1,8-cineole (5.5 17.2%), linalool (0.8 16.1%), camphor (0.5 16.6%), borneol (t 6.5%), α-pinene (2.7 6.5%) and lavandulol (t 6.0%), while the essential oils of A. kellalensisfrom the Kallar region were chamazulene (49.0 52.6%), α-bisabolol (20.5 -25.1%), β-myrcene (2.8 3.7%), and αpinene (1.6 4.5%). Although, the essential oils from the flowers and leaves of A. kellalensiswere characterized by high level of oxygenated sesquiterpenes, those of A. wilhelmsiiwere characterized by high level of oxygenated monoterpenes.