Abstract: AIM: To investigate the antioxidant activity of Garcinia xanthochymus leaf, root and fruit extracts in vitro. METHODS: The antioxidant activity of petroleum ether, ethyl acetate, n-butanol and water fractions from each plant part of G. xanthochymus were assessed by determining the total phenolic content, evaluating the reducing power, measuring the capability for scavenging free radicals, as well as its ability to inhibit DNA cleavage, using appropriate assay systems. In addition, high performance liquid chromatography (HPLC) was used to quantify the Garcinia biflavone GB-1a in the fractions from each plant part of G. xanthochymus. RESULTS: Six fractions showed antioxidant activity, especially the ethyl acetate fraction from the leaf of G. xanthochymus showed a potent antioxidant activity which was similar to that of the standard antioxidant BHT. CONCLUSION: This study provided a theoretical reference for the further isolation of natural antioxidants from G. xanthochymu.