Syrian oregano (Origanum syriacum L., Lamiaceae) is a very popular culinary herb that has been used through the ages in traditional medicine mainly in Lebanon and the Arab world. The subject of this study was the microscopic analysis of the herbal drug Origani syriaci folium, as well as the chemical analysis of its essential oil components. Plant materials originated from Arabsalim - South Lebanon and were collected in 2010. The presence of very dense clusters of multicellular covering trichomes (510 μm × 18.47 μm) and peltate secretory glands (∅ 87.95 μm) with eight cells were observed. The essential oil of Origani syriaci folium was isolated and quantified using hydrodistillation according to SPhC 1997. The content of essential oil was 95 ml/1000 g, i.e. 9.5% (V/m). The volatile constituents of Origani syriaci folium were qualitatively and quantitatively evaluated using SPME GC/MS. The two dominant constituents identified in Syrian oregano leaves were carvacrol (78.4%) and thymol (17.9%).