Water-distilled essential oil from the leaves of Artemisia absinthium L. collected from Ardabil, north-western Iran, was analyzed by Gas chromatography and mass spectrometry (GC and GC-MS). In the leaf oil of A. absinthium, 19 components, which represented 100% of the total composition were identified. 1,8-Cineole (36.46%), borneol (25.99%) and camphor (10.20%) were the major components in this oil. The leaves of A. absinthium was investigated to analyze their antimicrobial activity, antioxidant activity and total phenolic content. The present study revealed that the leaf essential oil of A. absinthium indicated significant activity against Candida albicans. Killing kinetics of various microorganisms treated with leaf oil of A. absinthium indicated that C. albicans is the most vulnerable. The total phenol contents of the leaf oil of A. absinthium was determined to be 168.67 ± 9.50 μg gallic acid equivalent/mg sample. Antioxidative properties of the leaves essential oil of A. absinthium was determined by 3 methods: The Ferric-reducing antioxidant power (FRAP), radical-scavenging capacity of the oil or bleaching of 2,20-diphenylpicrylhydrazyl (DPPH) and β-Carotene-linoleic acid assay. The ferric reducing power of the essential oils was determined to be 10.67 ± 0.45 gallic acid equivalent (mg/g). The leaf essential oil of A. absinthium reduced the concentration of DPPH free radical (61.4 ± 1.4%, 10 mg/ml of essential oil) with an efficacy lower than that of reference oil Thymus x-porlock (69.3% inhibition). IC50 for DPPH radical-scavenging activity was 5.85 μg/ml. In β-carotene-linoleic acid test system, oxidation of linoleic acid was effectively inhibited by A. absinthium oil (58.56 ± 2.5%, amount of essential oil 0.625 mg/ml). The results suggest application of A. absinthium oil as a natural antioxidant agent. Key words: Artemisia absinthium, essential oil, 1,8-cineole, antimicrobial activity, antioxidant, total phenolic content.