Algerian flora is rich in medicinal plants used locally to care for many sicknesses and diseases. Ridolfia segetum is one of these plants that grows in the southwest of the country in the Saoura Bechar region. The essential oil of seeds of Ridolfia segetum was extracted by hydro distillation and analyzed by chromatography and mass spectrography (CG/MS). The obtained results show that the most important compounds are carvone (69.9%) and apiole (12.41%) as major products and dihydrocarvone (6.66%) and limonene (5.62%) and traces of perillaldehyde, dihydrocarveol, linalool, p-cymene, and β-pinene. More characteristics of the essential oil of seeds of Ridolfia segetum have been also proclaimed at the end of this paper.