OBJECTIVE: To investigate the xanthones from Tibetan medicine Halenia elliptica and their antioxidant activity.METHODS: Column chromatography over normal phase silica gel, reversed phase silica gel, Sephadex LH-20, and recrystallization techniques were used to isolate and purify constituents from Halenia elliptica. Infrared spectrometry, mass spectrometry, and nuclear magnetic resonance spectrometry were used to identify the structure of compounds. The antioxidant activity was evaluated by measuring the content of malondialdehyde product in mice liver cell microsomal induced by ferrous-cysteine. RESULTS: Eight xanthones (compound I-VIII) were isolated and identified from the ethyl acetate extract of Halenia elliptica, among which 1,7-dihydroxy-2,3,5-trimethoxyxanthone was a novel compound. Compound I, III at 10 microg/ml and 100 microg/ml could inhibit the production of malondialdehyde in mouse liver microsomes in vitro. CONCLUSION: Eight xanthones were isolated and they have certain antioxidant activity.