Thirty-eight aroma-active compounds were detected in commercial cold-pressed grapefruit oil using a time–intensity GC–olfactometry procedure. Identification of the aroma-active components was based on the combination of sensory descriptors, linear retention index values from DB-Wax and DB-1 columns and GC–MS data. Thirteen flavour components, which had not been previously reported in grapefruit oil, were identified. Compounds with the greatest aroma intensities include: 1,8-cineole, octanal, dodecanal, trans-4,5-epoxy-(E)-2-decenal, β-sinensal and nootkatone. The aroma activities of sulphur compounds such as 4-mercapto-4-methyl-2-pentanol and methional were surprisingly low and neither of the two putative grapefruit aroma impact compounds, 4-mercapto-4-methyl-2-pentanone and 1-p-menthene-8-thiol, was detected. Over 200 volatiles have been reported in grapefruit oil, but only 38 have significant aroma activity and 22 of these can be considered major aroma impact compounds. Copyright © 2001 John Wiley & Sons, Ltd.