The essential oil of Tanacetum (syn. Chrysanthemum) fruticulosum Ledeb. from Iran was investigated by GC, GC–MS and NMR spectroscopy. The oil is characterized by photo‐oxidation products of lavandulol and nerolidol. Ninety‐seven components, representing 93% of the oil, could be identified. The oil contains mainly monoterpenes [1,8‐cineole (8), camphor (12), lavandulol (13), lavandulyl acetate (25)]. The new 5‐isopropenyl‐2,2‐dimethyltetrahydrofuran‐3‐yl‐methyl acetates (30, 31) are trace constituents. Some new farnesyl derivatives [3,6;6,9‐bisepoxyfarnesa‐1,7(14),10‐trienes (43, 44, 48, 49), 7,10‐epoxyfarnesa‐1,5,11‐trien‐3‐ols (63, 64), 6,9‐epoxyfarnesa‐1,7(14)10‐trien‐3‐ols (80–83)] were identified by their NMR spectra. Copyright © 1999 John Wiley & Sons, Ltd.