Altitude is an important ecological factor that significantly affects essential oil content, yield and composition. In this study, conducted to examine the effects of altitude on essential oil content and composition ofO. majorana, plant samples were collected from the southern region of Türkiye at the beginning of flowering period from seven different altitudes (766 m, 890 m, 968 m, 1079 m, 1180 m, 1261 m and 1387 m) at 100 m intervals. The highest percentage of essential oil (6.50%) obtained by hydro-distillation was determined at 766 m altitudes. The GC–MS analyses revealed that low altitude affected some essential oil components positively. The linalool ratio, which is the major component of the essential oil ofO. majoranaspecies, was the highest at 766 m (79.84%) altitudes. Borneol, linalool oxide, trans-linalool oxide, caryophyllene,a-humulene, germacrene-D and bicyclogermacrene components yielded high values at 890 m altitudes. Thymol and α-terpineol, which have an important place in the essential oil composition, increased at 1180 m altitudes;a-terpinene,cis-sabinene hydrate, terpinene-4-ol and carvacrol increased at 1387 m altitudes.