The spectral properties of olive leaves were studied by visible and near-infrared spectroscopy to discriminate between the juvenile and adult origin of leaf samples. Spectral data from 400 to 2500 nm were recorded on 18 leaf samples from juvenile (6) and adult (12) seedling plants using four different sample presentations to the instrument. Spectra of leaves were remarkably similar owing to dominant features related to absorption by photosynthetic pigments (visible) and water (near-infrared), although high variability was observed for all the sample presentations tested. The fibre-optic probe presentation provided the best procedure as it maximised (in relative terms) the spectral variability attributable to differences between seedlings and minimised that arising from the sampling procedure. Principal component analysis (PCA) performed with average values per seedling showed that two groups can be clearly observed according to the origin (juvenile or adult) of the samples. This method could provide a rapid screening technique useful as a selection tool in olive breeding programmes. Copyright © 2006 Society of Chemical Industry