Abstract The hydrodistilled essential oil from the aerial parts of Chenopodium ambrosioides L. was analyzed by GC and GC/MS. Fifteen constituents, representing 95% of the oil, having six monoterpene hydrocarbons (85%) and nine oxygenated monoterpenes (10%), were characterized. The major components were Î±-terpinene (64%), p-cymene (19%) and ascaridole (7%).