摘要:Aim. It is well known that the pharmacological activity of essential oils depends on their major components, which may vary enormously. The aim of the present study was to determine the chemical composition of samples of essential oil of rosemary of different origins, in order to identify the main therapeutic constituents, according to European Pharmacopoeian (EP). Material and Methods. Analytical GC/MS was carried out on a total of eight samples of essential oil of rosemary: seven samples were commercial products from producers located in different geographical areas; the last sample was prepared in our labo- ratory from fresh flowering terminal sprigs of rosemary collected in Siena’s Province. results. The most representative constituents of the essential oils tested, were 1,8-cineole and camphor. Other components also occurred in significant quantities in some samples, for example and α- and β-pinene, limonene and caryophyllene, in- dicating clear phytochemical differences among samples. discussion. The high quantity of eucalyptol and camphor detected in the samples made them particularly suited for treating minor respiratory disorders. Eucalyptol is expectorant and liquefies bronchial secretions; camphor increases the interval bet- ween inspiration and expiration and increases the activity of the parasympathetic nervous system, facilitating respiration. On the other hand, the essential oils analyzed by us were not suitable for perfume production, because they contained little or no positive aromatic components.