We tested to determine if Mori Cortex Radicis extract has antioxidant activities and its potentialmechanism of action was explored. Anti-oxidative effects were tested by measuring free radicaland nitric Oxide (NO) scavenging activity, and reducing power. Since iNOS and COX-2 areimportant enzymes responsible for the production of free radicals in the cell, Mori Cortex Radicisextract was tested as to whether it could inhibit iNOS and COX-2 expression in LPS stimulatedRaw cells. 70% methanolic extract of Mori Cortex Radicis exerted significant DPPH free radicaland NO scavenging activities. In addition, the Mori Cortex Radicis extract exerted dramaticreducing power with maximal activity observed at 1 mg/ml (11-fold over control). Production ofiNOS induced by LPS was significantly inhibited by the Mori Cortex Radicis extract, suggesting itcould inhibit NO production by suppressing iNOS expression. COX-2 induced by LPS was alsosignificantly inhibited by the Mori Cortex Radicis extract. The extract contains well known anti-oxidant components including phenolics, flavonoids and anthocyanin at the concentration of0.23mg/g, 42.97mg/g and 12.08mg/g, respectively. These results suggest that 70% methanolicextract of Mori Cortex Radicis exerts significant anti-oxidant activity via inhibiting iNOS andCOX-2 induction.