Aroma compounds of Rosmarinus Officinalis were hydrodistilled and identified using Gas Chromatography - Mass Spectrometry (GC-MS). The major aroma constituents were 1,8-cineole (52.8 %), camphor (11.9 %), alpha-pinene (10.2 %), borneol (7.5 %), and camphene (3.0 Rosmarinus Officinalis can be used as an easily accessible source of natural antioxidants and as a possible food supplement and as a phytochemical. Antioxidant activity and radical scavenging were investigated. Different bioassays were used, namely, scavenging of the diphenyl picrylhydrazyl (DPPH) radical using, Electron Spin Resonance (ESR) technique and inhibition the oxidation of linoleic acid catalyzed by soy lipoxygenase-1 measured by spectrophtometric and voltametric assays. The results of DPPH radical scavenging activity expressed as SA(DPPH) and, that of antioxidative activity obtained as inhibition constant 50, IC50,vealed a remarkable activity for rosemary essential oil compared with the known synthetic antioxidants at various concentrations.