The genus Phagnalon Cass., included in the Asteraceae family, has a wide distribution, expanding from Macaronesia in the West to the Himalayas in the East, from South France and Nord Italy to Ethiopia and Arabian Peninsula. Various species of Phagnalon have been used in the popular medicine of several countries as medicinal herbs and food. The extracts and the secondary metabolites, have a varied application spectrum at several biological levels, with antimicrobial, antioxidant, antidiabetic, antitumor, etc. properties having been reported. The essential oils of four taxa, Phagnalon rupestre, Phagnalon saxatile var. viride, and Phagnalon rupestre subsp. illyricum var. metlesicsii collected in Sicily (Italy), never previously investigated, and of Phagnalon graecum collected in Greece, were analysed by gas chromatography-mass spectrometry (GC-MS). All the oils were very rich in monoterpene hydrocarbons, with β-pinene as main constituent. Chemotaxonomic considerations with respect to all the other oils of Phagnalon taxa were carried out.