In this study, it has been aimed to determine the effect of altitude on fatty acid composition of seed oil of wild Achillea wilhelmsii from Turkey’s flora. The fatty acid compositions were determined by gas chromatography (GC). The total lipid contents of seed (at altitude 1000-1080 m, 1600-1650 m and 1850-1900 m) were found to be 4.17, 4.27, and 2.73%, respectively. The lowest total lipid level (2.73%) was 1850-1900 m and significant as statistical. Total saturated (∑SFA), monounsaturated (∑MUFA) and polyunsaturated (∑PUFA) acid contents of seed oils at different altitude were significant difference. But fatty acid profiles were quite similar. According to the obtained results, ∑PUFA ɷ-6 significantly decreased and ∑PUFA ɷ-3 significantly increased with altitude. The major components of A. wilhelmsii seed oil are palmitic (C16:0), oleic (C18:1 ɷ-9) and linoleic (18:2 ɷ-6) acids. C16:0 and C18:1 ɷ-9 contents increased with altitude but 18:2 ɷ-6 content decreased with altitude. The quantities of other fatty acids ranged at different altitude in the terms of increase or decrease as statistical. The ɷ-6/ɷ-3 ratios were 67.28% at 1000-1080 m, 17.84% at 1600-1650 m and 9.53% at 1850-1900 m.
