the paper reports the composition of the essential oil from aerial parts (leaves) of stachys byzantina (lamiaceae) from north-west of iran. the essential oil was extracted by hydrodistillation from selected plants and its chemical composition was determined by gc-ms system. the mass fraction of oil on dry weight base was 0.4 %. altogether, 21 compounds were identified corresponding to 87.9 % of the total oil. the main components were germacrene d (9.6 %), menthone (6.9 %), 1,8-cineole (14.8 %), -terpineol (7.8 %), cubenol (9.9 %), -cadinol (6.8 %) and linalool (12.9 %).