ABSTRACT Hydrodistilled essential oils (HD) of dried aerial parts of Achillea fragrantissima cultivated in Egypt and Madinah Monawara, Saudi Arabia, and their volatiles extracted by solid phase microextraction (SPME) were analyzed using Gas Chromatography – Mass Spectrometry. Thirty – four constituents of the essential oil of Egyptian A. fragrantissima were identified, representing 90.15% of the total oil constituents, while SPME revealed 15 components constituting 94.72% of the volatile material. Santolina alcohol, artemisia ketone, α-thujone, 4(10)-thujen-3-ol, β-thujone, yomogi alcohol and trans-sabinyl acetate were the predominant components in both extracts, with quantities varying with extraction method. Many terpenes e.g. β-pinene, sabinene, α-terpinene, p-cymene, linalool, p-menth-2-en-1-ol, 4(10)-thujen-3-ol, borneol, carvone, p-menth-1-en-3-one, bornyl acetate and germacrene D, were identified for the first time. α-Thujone, 4-terpineol, trans-pinocarveol, and spathulenol were the major components among 42 identified components accounting for 93.65% of the total identified volatiles of Madinah hydrodistillate. Monoterpenes concentration was higher in Madinah SPME volatile extract than in HD essential oil. A. fragrantissima essential oil of Madinah exhibited higher antioxidant activity (IC50 1.09 mg/ml) than did Egyptian oil (IC50 1.72 mg/ml), consistent with the differences in phenolic content and volatile constituents identified in both oils.