Abstract Essential oils isolated from the aerial parts of two different populations of Tanacetum dolichophyllum (Kitam.) Kitam. (syn. Tanacetum longifolium Wall.) were analyzed by GC and GC/MS in order to determine the variation of concentration in their constituents. Plant collected from Dayara meadow (Sample I) afforded cis-lanceol (11.8%), β-pinene (10.7%), (E)- β-farnesene (7.4%), α-bisabolol (7.2%), β-eudesmol (5.2%) and terpinen-4-ol (5.1%) as the major constituents, whereas in the sample collected from Tungnath (Sample II) β-eudesmol (31.4%), α-bisabolol (10.7%) were the most abundant components followed by neryl acetate (5.8%) and (E)-β-farnesene (5.7%). The composition was dominated by sesquiterpene hydrocarbons and oxygen containing sesquiterpenes (49.2â71.1%). The oils are clearly different from those of all other previously reported T. dolichophyllum oils. Key Word Index: Tanacetum dolichophyllum essential oil compositionβ-eudesmolcis-lanceolα-bisabolol