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 (MAHD) apparatus. The yields were 0.46% ± 0.03 for the HD and 0.48% ± 0.03 for the MAHD (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 (10.4â17.2%), sabinene (11.6â14.6%), α-terpineol (4.4â5.2%), terpinen-4-ol (2.4â5.7%), and, among sesquiterpenes, γ-eudesmol (8.7â17.9%) and 6S,7R-bisabolone (4.4â14.9%). 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 MAHD were richer in sesquiterpenes (47.9%, 42.7% and 47.6%, respectively). Key Word Index: Achillea millefolium Asteraceaedistillation methodsessential oil composition1,8-cineolesabineneγ-eudesmol