Background: It has been considered by researchers to study the possibility of replacing chemical food additives such as synthetic antioxidants by natural products especially medicinal plants.

Objective: The aims of this study were as follow: (i) to determine the major components of the essential oil of Lavandula angustifolia. (ii) to evaluate the antiradical activities of this essential oil by DPPH°, ABTS°+ and β-carotene bleaching assays and (iii) to evaluate the antioxidant activity of this essential oil in crude soybean oil.

Methods: The main chemical components of essential oil were identified by GC/MS. Antiradical activities of mentioned essential oil was measured by different methods and finally, its antioxidant activity was determined in crude soybean oil system by Oven method.

Results: Six main compounds were identified: linalool (27.89%), camphore (10.82%), 1, 8 cineol (9.05%), inalol acetate (8.86%), borneol (7.29%) and α-terpineol (5.04%). EC₅₀ of essential oil was 35.54 ± 1.58 mg/ml. In ABTS°⁺ assay, maximum antioxidant activity was related to 40 mg/ml concentration of essential oil. In β-carotene bleaching assay, maximum antioxidant activity of essential oil was related to the 10 mg/ml concentration of it (54.4 percent radical scavenging activity ). In oven test, essential oil could inhibit of primary and secondary oxidation products of crude soybean oil at 0.8 mg/ml that was almost equal to BHA at 0.2 mg/ml.