The present study aimed to determine the chemical composition and antioxidant activity of immortelle (Helichrysum italicum (Roth) G. Don) and yarrow (Achillea millefolium L.) essential oils isolated from the aerial plant parts on a semi-industrial scale by steam and water-steam distillation, respectively. The qualitative composition of the essential oils obtained was determined by GC/MS and their quantitative composition by GC/FID method. Their antioxidant activity was estimated by using DPPH,

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... BTS and FRAP assays. The most abundant components in the immortelle essential oil were a-pinene (22.4%), g-curcumene (13.2%), neryl acetate (9.8%) and b-selinene (8.7%), while yarrow essential oil contained 1,8-cin-eole (25.5%), CIS-thujone (10.8%), camphor (7.3%) and artemisia ketone (6.9%) in the highest percentage. According to the EC 50 values yarrow essential oil showed better radical (DPPH and ABTS) scavenging activity than immortelle essential oil (7.71 mg/cm 3 vs. 8.94 mg/cm 3 after 20 minutes of incubation with DPPH radical ; and 26.03 mg/cm 3 vs. 88.52 mg/cm 3 after 24 minutes incubation with ABTS radical, respectively). On the other hand, immortelle essential oil showed better ferric ion reducing power (7.16 mgEFe2+/g vs. 5.72 mgEFe2+/g essential oil) in comparison to yarrow essential oil. However, the results obtained indicated a low antioxidant activity of both essential oils studied.