The effects of Ashwagandha root powder (0.7 and 1.4 g/kg body weight/day), administered for 15 and 30 days, was investigated on lipid peroxidation (LPO), superoxide dismutase (SOD) and catalase (CAT) activities in mice. While 15 days treatment with Ashwagandha root powder did not produce any significant change, 30 days treatment produced a significant decrease in LPO, and an increase in both SOD and CAT. Our findings indicate that Ashwagandha root powder possesses free radical scavenging activity, which may be responsible for its pharmacological effects.