abstract the chemical composition of the essential oil from flowering tops of achillea millefolium l. isolated by different distillation methods was studied. samples were hydrodistilled with clevenger-type (hd), simultaneous micro-distillation-extraction (smde), and microwave (microwave-assisted hydrodistillation) apparatus. the yields were 0.46% +/- 0.03 for the hd and 0.48% +/- 0.03 for the microwave-assisted hydrodistillation (v/w, volume/dry weight). the oils were analyzed by gc and gc/ms and a total of 58 components were detected. the major compounds in the oils were 1,8-cineole (10.4-17.2%), sabinene (11.6-14.6%), -terpineol (4.4-5.2%), terpinen-4-ol (2.4-5.7%), and, among sesquiterpenes, -eudesmol (8.7-17.9%) and 6s,7r-bisabolone (4.4-14.9%). from a qualitative point of view, no relevant differences between the different methods of isolation were observed, while statistically significant differences on relative percentage were noticed. oils obtained by hd showed a higher amount of monoterpenoid compounds (69.2%), while l-smde, h-smde and microwave-assisted hydrodistillation were richer in sesquiterpenes (47.9%, 42.7% and 47.6%, respectively). key word index: achillea millefolium asteraceaedistillation methodsessential oil composition1,8-cineolesabinene-eudesmol