abstract the composition of the essential oil hydrodistilled from the aerial parts of artemisia herba-alba asso. growing in jordan was determined by gc and gc/ms. the oil yield was 1.3% (v/w) from dried tops (leaves, stems and fowers). forty components corresponding to 95.3% of the oil were identifed, of which oxygenated monoterpenes were the main oil fraction (39.3% of the oil), with - and -thujones as the principal components (24.7%). the other major identifed components were: santolina alcohol (13.0%), artemisia ketone (12.4%), trans-sabinyl acetate (5.4%), germacrene d (4.6%), -eudesmol (4.2%) and caryophyllene acetate (5.7%). the high oil yield and the substantial levels of potentially active components, in particular thujones and santolina alcohol, in the oil of this jordanian species make the plant and the oil thereof promising candidates as natural herbal constituents of antimicrobial drug combinations.