The roots and rhizomes of Tanacetum parthenium (L.) Schulz. Bip. (Asteraceae), have been used in Iranian traditional medicine under the name of Aqhovan, as digestive and stomachic tonic. Composition of the essential oil, which was obtained from the root of T. parthenium collected from Karaj, was determined by gas chromatography, combined GC/MS and GC/IR. In total, 20 components (92% of essential oil) were identified. Major constituents were camphor (30.2%), (Z)- chrysanthenyl acetate (26.5%), α-farnesene (11.1%) and spathulenol (8.2%).