Abstract The composition of the essential oil ofTanacetum khorassanicum (Krasch.) Parsa, an endemic plant of Iran was analyzed for the first time by GC and GC/MS. Thirteen components, mainly monoterpenes, were characterized in the oil, representing 89.1% of the total components detected. (E)-Myroxide (19.8%), camphor (16.4%), isopulegone (13.4%) and 1,8-cineole (11.4%) were identified as major constituents.