10.22376/ijpbs.2019.10.1.p1-12 Volume 8 Issue 1 2017 (January - March) To obtain much better information about the medicinally useful essential oil of the rhizome of lessThan i greaterThan Alpinia allughas lessThan /i greaterThan Rosc., the oil from the rhizome collected from Guwahati, Assam, has been isolated by hydrodistillation and analysed by GC and GC/MS. Twenty-eight compounds representing 95.14% of the oil have been identified. Norisoprenoid related antioxidant β-ionol is the major component (15.53%). In a rare observation, the sesquiterpenes & derivatives (39.47%) and monoterpenes & derivatives (39.42%) are almost in equal amounts. Among the monoterpenes & derivatives, the terpinen-4-ol (11.51%), 1,8-cineole (8.91%) and fenchyl acetate (7.55%) are main. Among sesquiterpenes & derivatives, the major components are found to be β-selinene (13.77%) and γ-elemene (6.30%). The oil shows good antibacterial activity against lessThan i greaterThan Staphylococcus aureus lessThan /i greaterThan . NIKHIL KUMAR AND VIJAYATA Alpinia allughas, Alpinia nigra, Zingiber nigrum,Zingiberaceae essential oil composition β-ionol 143-147