Background: Oenanthe fistulosa is an Algerian medicinal plant used in traditional medicine to treat different diseases. Objective: This present research aimed to carry out the chemical composition of essential oils from the aerial parts of Oenanthe fistulosa. Methods: Oils were extracted by hydro-distillation using Clevenger apparatus, and analyzed by Gas Chromatography Mass Spectrometry (GC-MS). Results: Eighteen components have been identified, and have been classified into six groups: oxygenated sesquiterpenes (7 components), hydrocarbon sesquiterpenes (4 components), oxygenated diterpene (1 component), alkanes (3 components), aldehydes (2 components) and ketone isoprenoid (1 component). The major groups were alkanes and the oxygenated sesquiterpenes (42.61 and 27.23%, respectively). In the alkanes groups we find three major components, such as: heptacosane (3.79%), 1-Eicosane (4.39%) and heneicosane (34.43%). In the sesquiterpene oxygenated we find two major components, which are: bylongipinocarveol (3.81%) and caryophyllene oxide (14.30%). In the aldehydes group, the major components is octadecanal with a rate of 6.68%, where the diterpeneoxygenated group was represented by phytol component (5.05%). Conclusion: This study is the first investigation to the chemical composition of essential oil of the species O. fistulosa L. growing in Algeria. The GC-MS analysis of the essential oils reveals the presence of 23 components, in which 18 products were identified. Where the caryophyllene oxide as main copound, which is effective in preserving food, drugs and cosmetics.