Xin, H., Wu, B., Zhang, H., Wang, C., Li, J., Yang, B. and Li, S. 2013. Characterization of volatile compounds in flowers from four groups of sweet osmanthus (Osmanthus fragrans) cultivars. Can. J. Plant Sci. 93: 923-931. Headspace-solid-phase microextraction (HS-SPME) and gas chromatography-mass spectroscopy (GC-MS) were used to characterize the volatiles in flowers of four cultivar groups of sweet osmanthus (Osmanthus fragrans Lour.), including Thunbergii, Latifolius, Aurantiacus and Semperflorens Groups. A total of 72 volatiles were identified. Volatile compounds and their relative contents varied among the four groups or cultivars within each group. Briefly, β-ionone, cis-linalool oxide (furan), trans-linalool oxide (furan) and linalool were the most common volatiles in tested cultivars, while (E)-2-hexenal, (Z)-3-hexen-1-ol and hexanal were abundant in several cultivars. Principal component analysis showed that the Aurantiacus Group was rich in cis- and trans-linalool oxide (furan), whereas the Latifolius group had high levels of (E)-2-hexenal and (Z)-3-hexen-1-ol. Our results contribute to our understanding of the volatile composition and content in flowers from different osmanthus groups and will facilitate development of new osmanthus cultivars to meet requirements of the food and fragrance industries.