Desmodium gangeticum is herbal species which is widely used in the indigenous system of medicine and is reported to contain flavone and isoflavanoid glycosides. In view of its wide use and it's chemical composition, this study was aimed at examining the antioxidant activity of the extract of D. gangeticum. The extract was studied for diphenyl picryl hydrazyl (DPPH), nitric oxide, ferryl-bipyridyl and hypochlorous acid scavenging activity along with lipid peroxidation. Nitric oxide was generated using sodium nitroprusside and was studied using Griess reagent. In order to study the iron chelating capacity of the extract, the percentage ferryl-bipyridyl inhibition was studied. Hypochlorous acid scavenging activity was tested by measuring the inhibition of 5-thio-2-nitrobenzoic acid oxidation. The extract was also studied for lipid peroxidation assay by thiobarbituric acid-reactive substances (TBARS) method using rat brain homogenate. The results indicate that D. gangeticum extract has potent antioxidant activity. © 2003 Pharmaceutical Society of Japan.