Abstract Aerial parts of Ruta chalepensis L. plant grown under North Indian plain conditions were hydrodistilled to obtain essential oils from plants harvested at different stages of growth and were analyzed by GC and GC/MS. Nineteen compounds were identified representing 85.4â93.3% of the oil. 2-Undecanone (41.3â67.8%) was found to be the major compound followed by 2-nonanone (5.2â33.6%), 2-nonyl acetate (2.8â15.3%) and 2-dodecanone(<0.1â11.6%).