OBJECTIVE:To investigate antioxidant effects of different extract parts from Aquilaria sinensis leaves. METH-ODS:A. sinensis leaves were extracted by reflux extraction with petroleum ether,ethyl acetate,absolutely ethanol,water to obtain corresponding parts (AGP,AGE,AGA and AGW parts). The ability of different extracts eliminating ABTS+ free radical,DPPH free radical and O2-free radical and reducing Cu2+ were investigated. IC50 was also calculated. Vitamin C(VC)was used as positive control in above tests. RESULTS:Those parts eliminated above free radicals and reduced Cu2+ in concentration-dependant manner, among which maximal elimination rate of AGA and AGW parts to ABTS+ free radical were 100% and 81.07%(IC50=14.89,23.12 mg/L)and higher than that of VC(88%);those of other parts were less than 50%. The maximal elimination rate of AGA parts to DPPH free radical was 67.74%(IC50=47.96 mg/L),but still lower than that of VC(91.44%);the elimination rates of other parts were all weak and lower than 40%. The maximal elimination rates of AGA and AGW parts to O2-free radical were 67.79% and 61.79%(IC50=393.01,421.04 mg/L),but still lower than that of VC(88%);the elimination rates of other parts were all lower than 33%. The maximal reduction percentage of AGP,AGE,AGA and AGW parts to Cu2+ were all higher than 50%(IC50=55.99, 40.27,25.44,31.06 mg/L,respectively),but still lower than that of VC (100%). CONCLUSIONS:Different extract parts from A. sinensis leaves have antioxidant activity in vitro,and that of AGA is the strongest.