Essential oils obtained by hydrodistillation from the aerial parts and fruits of five taxa of genus Grammosciadium DC., belonging to subgenus Grammosciadium (G. confertum Hub.-Mor. & Lamond, G. cornutum (Nabelek) C.C. Towns., G. macrodon Boiss. subsp. macrodon, G. macrodon Boiss. subsp. nezaketae B. Bani and G. daucoides DC.), collected from different locations in Turkey, were simultaneously analyzed by GC and GC/MS systems. 124 components representing 71.1-99.8% of the total contents were identified in the oils. Oil samples from fruits and aerial parts of the plants showed different chemical profiles with regard to species. We have herein demonstrated that the chemical composition of essential oil samples from G. cornutum, G. macrodon subsp. macrodon, G. macrodon subsp. nezaketae (an endemic subspecies), and G. confertum (an endemic species) growing in Turkey was determined for the first time. Hexadecanoic acid (13.3-21.2% and 48.1-59.8%) was the main component of the samples of G. cornutum and G. confertum, respectively, while caryophyllene oxide (13.1-29.2%) was the major constituent in the samples of G. macrodon subsp. nezaketae and G. macrodon subsp. macrodon as well as.-terpinene (61.9%) and carvacrol (68.9%) in G. daucoides samples. In addition, pentacosane can be considered a chemotaxonomic marker for the essential oil of G. macrodon subsp. macrodon.