Abstract Essential oil from the rhizomes of Zingiber neesanum (Graham) Ramamoorthy from the Western Ghats region of southern India was isolated and characterized by GC and GCâMS. Oil constituents were identified by comparison of individual mass spectra with databases and the literature, linear retention indices and coâinjection. Sixtyâone constituents, comprising 97.4% of the oil, were identified. Phenylbutanoids, viz. ( E )â1â(3â²,4â²âdimethoxyphenyl)butadiene (31.1%), a potential antiinflammatory compound, and ( E )â1â(3â²,4â²âdimethoxyphenyl)butâ1âene (23.1%) were isolated from the oil by prep. TLC, characterized by IR, UV, 1HâNMR and MS and quantified by external standardization. ( E )â Î²â ocimene (12.7%), Î²â pinene (7.4%) and linalool (4.0%) were the major terpenoid constituents in Z. neesanum rhizome oil. Copyright Â© 2007 John Wiley &amp; Sons, Ltd.