ETHNOPHARMACOLOGICAL RELEVANCE: Swertia chirayita, a medicinal herb endemic to the Tibetan region, is used as a special remedy for liver disorders. The hepatoprotective activity of its plant extracts has been associated with its antioxidant activity. This paper aims to investigate the in vitro and in vivo antioxidant effects of Swertia chirayita extracts (SCE).MATERIALS AND METHODS: Antioxidant ability of Swertia chirayita was investigated by employing several established in vitro methods. In vivo antioxidant activity was tested against CCl(4)-induced toxicity in mice. The levels and activities of malondialdehyde (MDA) and antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH), were then assayed using standard procedures. RESULTS: SCE exhibited strong antioxidant ability in vitro. The liver and kidney of CCl(4)-intoxicated animals exhibited a significant (p<0.001) decrease in SOD, CAT, and GSH levels. Additionally, these organs exhibited a significant (p<0.001) increase in MDA level. CCl(4) did not exhibit toxicity on mice treated with SCE and Vitamin E. The effects of Swertia chirayita (three dosages) were comparable to those of Vitamin E, except in MDA level in the liver and GSH level in the kidney (p<0.05). CONCLUSION: This study suggests that the ethanolic extract of Swertia chirayita possesses in vitro and in vivo antioxidant effects. This supports the traditional use of Swertia chirayita in Tibetan medicine to cure liver diseases.