The compositions of the essential oil of the leaves and stem-bark of Origanum dubium Boiss (Labiatae) were analysed for the first time by means of gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). A total of forty-one components were identified; qualitative and quantitative differences in the oil compositions were observed. The major constituents of the leaf oil were 1,8-cineole, linalool, and camphor while γ-cadinene, linalool, β-farnesene, and δ-cadinene were major components of the stem-bark oil.