A thin layer chromatography study was conducted on the essential oils from leaf, stem-bark and root-bark of the genus Cinnamomum found in Sri Lanka. Wild Cinnamomum species such as Cinnamomum capparucoronde, Cinnamomum citriodarum, Cinnamomum dubium, Cinnamomum litseaefolium, Cinnamomum ovalifolium, Cinnamomum rivulorm and Cinnamomum sinharajanse were investigated, together with the cultivated cinnamon (Cinnammum verum, synonym Cinnamomum zeylanicum) to identify their major chemical constituents. Cinnamaldehyde, eugenol, linalool, a-terpineol, acetyleugenol and cineole were primarily detected. There were some variations among the species in the main components of leaf and stem-bark oils. Major constituents in stem-bark oil were either cinnamaldehyde (Cinnamomum citriodorum and Cinnamomum verum), linalool (Cinnamomum dubium and Cinnamomum ovalifolium), α-terpineol (Cinnamomum litseaefolium) or eugenol (Cinnamomum capparucoronde and Cinnamomum rivulorum). In oil extracted from the leaf, the principal consti...