The phenol contents and the antioxidant activities of 12 Chinese longan cultivars were studied. The polyphenols of longan pericarp and seed demonstrated significantly higher antioxidant capacities than did the pulp. The ferric reducing antioxidant powers of longan fruits were closely correlated with the polyphenol contents (r(2) = 0.8609, p < 0.001, n = 36). 52.9 mg g(-1) (dry matter) polyphenols were extracted from the pericarp of cultivar Wulongling fruit with acetone aqueous along with ultrasonic treatment. Further fractionation was performed by Sephadex LH-20 chromatography. The results suggested that gallic acid (GA) and ellagic acid (EA) were not the major contributors to the antioxidant activity of longan pericarp. 15 other phenolic profiles in longan pericarp along with a number of unknown structures were revealed with high-performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-ESI-MS) analysis. The rich array of phenolic compounds of several different types in longan pericarp extract might form a synergistic multilevel defence system against oxidation. (C) 2009 Elsevier B.V. All rights reserved.