The hydrodistilled oil of the Chaerophyllum macropodum aerial parts was analyzed by gas chromatography-flame ionization detection (GC-FID) and GC-mass spectrometry (GC-MS). Among the forty one compounds identified of essential oil trans-ocimene (49.2%), cis-ocimene (23.6%), gamma-terpinene (7.7%), beta-myrcene (4.4%), o-cymene (2.8%), p-cymene (2.7%), and fenchyl acetate (2.7%) were the major constituents. Antioxidant activity of the essential oil was determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity and beta-carotene bleaching test. The essential oil showed the weak antioxidant property in comparison to that of synthetic standard butylated hydroxytoluene (BHT).