The essential oils of two scented geranium (Pelargonium spp.) cultivars grown on Reunion Island were investigated by GC-MS. The specific odour attributes of each single constituent were correlated with the olfactory impression of the two essential oils. The scent of the essential oil extracted from the well-known rose-scented geranium cultivar, Pelargonium cv. Rosé, is based on the rosy, fruity, minty and faintly citrusy aromas of the main components, citronellol (21.9%), geraniol (18.3%), linalool (16.0%), citronellyl formate (11.6%) and isomenthone (7.6%), accompanied by minor compounds of olfactory significance, including geranyl formate (4.0%), nerol (1.7%), geranyl tiglate (1.6%) and neryl propanoate (1.5%) in particular. The volatile constituents of the essential oil of a second geranium cultivar (Pelargonium sp.) are dominated by monoterpene hydrocarbons, of which the most abundant is p-cymene (35.8%). This oil possesses a very unusual, although very pleasant, 'citrusy-peppery-spicy' and herbaceous scent, somewhat pungent, which is rather reminiscent of thyme. Chemotaxonomic considerations about the genus Pelargonium are also discussed.