Dendrobium nobile Lindl.(Orchidaceae), Vietnamese name as Hoang thao dui ga is an epiphytic plant on high tree branches. It grows widely in humid mountainous areas in Vietnam. The plant is used to treat fever, dry mouth, dry throat, increase vitality in traditional medicine. In the course of study on chemical composition of Dendrobium nobile Lindl. in Vietnam, this paper describes the extraction and structure evaluation of five known compounds, including E-1,5-bis(4-hydroxyphenyl)-pent-1-en-3-one (1) together with ferulic acid (2), 4-hydroxy cinnamic acid (3) umbellic acid (4) and 3-(4-hydroxyphenyl) propionic acid (5). The stems of this plant were collected, identified, dried and extracted in different polarity solvents. These substances were isolated from the ethyl acetate and water fractions of methanol extract on the basis of column chromatography. Their structures were identified based on spectroscopic evaluation and comparison of corresponding authentic compounds. This is the first report of compound 1 from the Dendrobium genus
