Background: Smyrnium cordifolium belongs to Umbelliferae family which growing in the west and southwest of Iran and has nutritive and medicine use in the regions. Aim: Identification of chemical compositions of essential oil of S. cordifolium grown in different regions of Lorestan province and study effects of environmental factors on it. Methods: This plant was collected from five differen regions of Lorestan province and was investigated for quatitative and qualitative changes of its essential oil. The oils was injected to GC for identification of constituents. Results: Yields of essential oil were 0.07% to 0.55% in these different regions. The most amount of essential oil was related to Poldokhtar and the least amount to Aligoodarz. In the essential oil of different regions two oxygenated sesquiterpen Curzerene and Curzerenone had the most amount. Among common and remarkable components we can mention to Germacrene-D, Isopimarol and Phyllocladanol. In Kouhdasht and Khoramabad, Curzerene was the main component with 39.4 and 34.2 percentages respectively, and in Poldokhtar, Nourabad and Aligodarz it was Curzerenone with 49.4, 33.8 and 35.6 percentages.Also, in different regions Germacrene-D is abundant in the oil Discussion: The identified components of essential oil of different regions showed the differences and similarities from quantitative and qualitative point of view. GC/MS analysis revealed that the sesquiterpen compounds were the main components in different regions. α-pinene and β-pinene were just observed in Norabad and Aligodarz.