Variations in the essential oil composition of Achillea millefolium L. growing in Estonia and in other European countries, were determined. The oils were obtained in yields of 0.9-9.5 mL kg-1. A total of 102 components were identified. The quantitatively most important components of yarrow were sabinene, beta-pinene, 1,8-cineole, artemisia ketone, linalool, alpha-thujone, beta-thujone, camphor, borneol, fenchyl acetate, bornyl acetate, (E)-beta-caryophyllene, germacrene D, caryophyllene oxide, beta-bisabolol, delta-cadinol, chamazulene etc. Samples from Estonia contained high amounts of monoterpenes and chamazulene. High amounts of monoterpenes and chamazulene were also found in samples from Hungary, Greek, Moldavia, Latvia, Lithuania and Germany. The oils from France, Belgium, Russia, Armenia, Spain and Italy were rich in oxygenated monoterpenes and contained a little amount of chamazulene. The drugs from Greece, Estonia, Moldavia and Scotland were rich in sesquiterpenes. The Millefolii herba grown in Estonia conforms to the European Pharmacopoeia (EP) standards in the aspect of the essential oil contents.