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Abstract: Lemon verbena was cultivated in Syria and used in folk and Arabian medicine.Essential oil of fresh leaves is extracted, determined and analyzed with gas chromatography/mass spectrometry (GC-MS) whereas no one determined the composition of Syrian origin before. Leaves is harvested in three stages of growth: in May, which approves the highest rate of growth, July, mid-season, and October, full bloom. The major component were citral (geranial and neral), limonene, β-caryophyllene, limonene, Germacrene D, Ar-curcumene, γ-elemene, 1,8-cineol,cedrene and β-caryophyllene oxide. The study at growth stages showed significant differences in the percentages of the main constituents especially citral, Ar-Curcumene, β-caryophyllene oxide and limonene. geranial and neral range from 17 to 19.4% and from 19.3 to 25.6 %, respectively. In addition limonene ranges from 3.3 to 6.07% and β-caryophyllene oxide from 8.74 to 17.8%, while Ar-Curcumene 4.95% to9.85%.Moreover it’s the first time that E-nuciferol appears along with components. Antimicrobial activity of the essential oil of Lemon verbena were studied by the disk diffusion method. Whereas E.colihasmore sensitive than Staph. aureus and S. typhimurium in order and its increase in July

because of increasing the citral percentage.