Abstract The volatiles of Achillea millefolium L., cultivated in Iran, were obtained by hydrodistillation and supercritical (carbon dioxide) extraction methods. The volatiles were analyzed by capillary gas chromatography using fame ionization and mass spectrometric detections. The effects of different parameters, such as pressure, temperature, modifier volume and extraction time, on the supercritical fluid extraction (SFE) of A. millefolium volatiles were investigated. The results showed that, under a pressure of 300 atm, temperature 35°C, 5% methanol and dynamic extraction time of 20 min, extraction was more selective for germacrene D. Fifty compounds were identified in the hydrodistilled oil. The major volatile components of A. millefollium were 1,8-cineole (15.2%) and germacrene D (14.1%). However, by using supercritical carbon dioxide under optimum conditions, only two components constituted more than (60%) of the volatile concentrate.