The chemical composition of the essential oil obtained from Teucrium marum subsp. marum (Lamiaceae) was analysed by GC/MS and 30 components were identified. Isocaryophyllene (20.24%), beta-bisabolene (14.73%), beta-sesquiphellandrene (11.27%), alpha-santalene (10.97%), dolichodial (9.38%) and, alpha-caryophyllene (7.18%) were the main components. The antimicrobial activity of the essential oil was assayed against four phytopathogenic fungi and Rhyzoctonia solani resulted to be the most sensitive microorganism with a MIC value of 250 ppm. The antioxidant activity of the essential oil was evaluated using the DPPH test, 5-lipoxygenase test and luminol/xanthine/xanthine oxidase chemiluminescence assay.