The essential oil from the aerial parts of two cultivated subspecies from Porophyllum ruderale, Porophyllum ruderale subsp. macrocephalum (PRM) and Porophyllum ruderale subsp. ruderale (PRR) were obtained by hydrodistillation and analyzed by gas chromatography (GC) and GCâmass spectrometry (GCâMS). Monoterpenes were the most abundant components. The oil from PRM presented limonene (83.5%), myrcene (6.3%) and 1-undecene (5.4%) as the major compounds, while the oil from PRR contained E-Î²-ocimene (54.9%), limonene (25.2%) and Î²-pinene (10.1%) as the main components. These results suggest that the main component of the essential oil can differentiate the two P. ruderale subspecies.