The essential oils of two endemic Centaurea species from Turkey, C. mucronifera and C. chrysantha, collected in the same habitat, have been studied. The main compounds of the former were germacrene D (29.3%), β-eudesmol (17.4%) and β-caryophyllene (7.3%), while in the latter germacrene D (27.4%), caryophyllene oxide (9.5%) and bicyclogermacrene (5.4%) were detected among its major constituents. The two species produced many similar compounds in their essential oils that could be justified by the similar ecological conditions of their habitat, but also many differences were found that could confirm their taxonomic separation. © 2003 Elsevier Ltd. All rights reserved.