Abstract Chemical analysis and antimicrobial activity of essential oil isolated by steam distillation from Ambrosia artemisiifolia L., Asteraceae dried flowering herb were performed. Principal constituents were germacrene D (24.1%), limonene (16.83%), Î±-pinene (8.0%) and myrcene (7.4%). A significant bactericidal and fungicidal activity was observed against all microorganisms tested.