Hydro-distilled volatile oils from the aerial parts of Achillea oxyodonta (collected from two different locations), which is endemic to Iran, was analysed by GC and GC-MS. In the oil of A. oxyodonta from Shemshak sample, 54 compounds representing 95.68% of the total oil were characterized with camphor 13.18%; spathulenol 11.19%; 1,8-cineole 10.51%; salvial-4( 14)-en-1-one 4.82%; eudesm-4-en-6-one 3.17%; caryophyllene oxide 3.07%; filifolone 3.03% as the major components. In the oil obtained from A. oxyodonta sample collected in Soleghan, 49 compounds representing 97.98% of the oil were characterized. spathulenol 13.13%; camphor 12.83%; 1,8-cineole 11.15%; cis-β-Farnesene 8.21%; α-Cadinol 4.83%; salvial-4( 14)-en-1-one 4.19%; bornyl acetate 4.16%; isospathulenol 3.64%; germacrene D 3.45%; endo-1,5-Epoxysalvial-4( 14)-ene 3.09% was found as the main components. The results showed that there are qualitative similarities between the oils although the amounts of some corresponding compounds are different indicating that environmental factors strongly influence its chemical composition.