Rhizomes of sweet flag (Acorus calamus L.) were collected from Astrakhan state, Russia to define the volatile organic compounds in their essential oil. Rhizomes were washed, dried and subjected to simultaneous distillation – extraction (SDE) technique to extract the essential oil (4 ml/kg rhizome) then analyzed by gas chromatography–mass spectrometry (GC-MS) to isolated the volatile organic compounds. Chromatographic analysis of samples showed 14 bioactive compounds; Asarone, Beta-Pinene (β-pinene), Camphene, 1,2,3,4-tetramethyl-5-methylene-1,3-cyclopentadiene, Linalool, Camphor, γ-muurolene, Shyobunone, Dehydroxy-isocalamendiol, 1,2-Dimethoxy-4-methoxy-l-propenylbenzene, Acetic acid, 3-hydroxy-6-isopropenyl-4,8a-dimethyl-1,2,3,5,6,7,8,8a-octahydronaphthalen-2-yl ester, 9-Acetamido-1-methyl-3,6-diazahomoadamantane, 1,8-dimethyl-8,9-epoxy-4-isopropyl-spiro[4.5]decan-7-one,6-[1-(Hydroxymethyl)vinyl]-4,8a-dimethyl-4a,5,6,7,8,8a-hexahydro-2(1H)-naphthalenone.
Key Words: Acorus calamus L, Sweet flag, Rhizome, Volatile organic compounds, Asarone.