Abstract The essential oils of the air-dried aerial parts of Ocimum sanctum L. (syn. O. tenuiflorum L.f.), harvested in four stages of vegetation, were isolated by hydrodistillation and analyzed by capillary GC, GC/MS, and 1H-NMR. The 57 compounds, representing 90â94% of the oil, were identified after oil distillation under reduced pressure and separation by repeated flash chromatography. The content of the main constituents: Î²-bisabolene (13â20%) 1,8-cineole (9â33%) and methyl chavicol (2â12%) varied during development of the plant.