A new naturally occurring linear sesquiterpene (tanacetene) (1). having irregular non-head- to- tail attachment of isoprene units, a new long chain ester (2). and 10 known compounds have been isolated from hexane and chloroform extracts of the roots and aerial parts of Tanacetum longifolium wall. The structure of (tanacetene) (1). was established as (2E,6E,10E)-2,6,11-trimethyl-dodeca-2,6,10-triene and that of (2). as heptatriacontanyl eicosanoate by spectroscopic methods along with 10 known compounds. From the oily fraction twelve volatile compounds were identified by GC-MS. The roots of this plant were found to be a new major source of Z-spiroketalenol ether-6,7-epoxy-diyne in 3.2% yield on dry weight basis.