abstract the volatile constituents of the aerial parts of scorzonera undulata vahl subsp. deliciosa (guss.) maire obtained by steam distillation were analyzed by gc and gc/ms. thirty six constituents were identified in the oil and the main components of which were methyl hexadecanoate (30.4%), methyl linolenate (23.9%) and heneicosane (12.2%) the antimicrobial activity of the oil was also investigated. the scorzonera undulata subsp. deliciosa oil exhibited an interesting antibacterial activity against gram-positive and gram-negative bacteria except for pseudomonas aeruginosa but no antifungal activity was detected.