Objectives: To evaluate the antioxidant and free-radical scavenging activities of triethylchebulate (TCL), an aglycone isolated from the fruit of Terminalia chebula Retz. Materials and Methods: Microsomes, mitochondria and red blood cells (RBCs) were isolated from rat liver. The antioxidant capacities were evaluated by determining the inhibitory effects of TCL on lipid peroxidation, hydrogen peroxide (HO)-induced RBCs hemolysis and RBCs autoxidative hemolysis. The free-radical scavenging activities were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and 2,7-dichlorodihydrofluorescin diacetate (DCFH-DA) assay. Result: TCL significantly inhibited FeSO/Cys-induced microsomes lipid peroxidation and protected both HO-induced RBCs hemolysis and RBCs auto-hemolysis in a dose-dependent manner. Furthermore, TCL demonstrated potent DPPH free-radical scavenging ability with IC at 2.4 × 10M. In addition, TCL also moderately suppressed azide-induced mitochondria ROS formation. Conclusion: These results demonstrated that TCL was a strong antioxidant and free-radical scavenger, which might contribute to the anti-oxidative ability of Terminalia chebula Retz.