Ferulago glareosa Kandemir & Hedge. is an endemic species of the family Apiaceae for Turkey and has interesting morphological characteristics compared to the other members of the genus Ferulago Koch. In this study we investigated the essential oil compositions of the roots and aerial parts of F. glareosa for the first time and compared them with essential oil compositions of the roots and aerial parts of other species of the genus. In our study, major components of the essential oil of the roots were determined to be 2,3,6-trimethylbenzaldehyde (32.2 %), falcarinol (23.7 %), hexadecanoic acid (9.5%) and 2,5-dimethoxy-p-cymene (5.9 %); and major components of the essential oil of the aerial parts were found to be alpha-pinene (33.7 %), p-cymene (14.8 %), gamma-terpinene (13.2 %), (Z)-beta-ocimene (12.4%) and terpinolene (8.2 %). The essential oil compositions of F. glareosa root compare with essential oils components in the literature differ varies greatly. Hierarchical Cluster Analysis (HCA) was performed with Minitab software, utilizing 8 major components in the published 20 literatures, as well as in this study. Principal Component Analyses (PCA) were used in order to demonstrate chemotaxonomical variations in the composition of the essential oils of Ferulago species.