Stevia rebaudiana Bertoni, licorice (Glycyrrhiza glabra L.), carob (Ceratonia siliqua L.) and chicory (Chichorum intybus L.) are considered medicinal plants with many traditional uses such as sweetener plants. The volatile oils of these plants were isolated by steam distillation process. Identification of vol-atile compounds present in these volatile oils was assayed using Gas chromatography - Mass spectrome-try (GC-MS). The volatile oil contents were about 0.24, 0.12, 0.08, and 0.27% of dried stevia leaves, lico-rice roots, carob pulp and chicory roots, respectively. The nerolidol, benzyl, δ.cadinene and caryophyllene were the major volatile compounds of stevia leaves, while methyl chavicol and benzaldehyde were the main ones of licorice. Carob pulp contained the hexanoic acid as the major component. The main con-stituents were benzoic acid, verapamil and verbenone in chicory roots. The volatile oils are very impor-tant for their activity as an anti-inflammatory drug, and also could be used as an anti-bacterial and fla-vouring agents in the field of food industry.