Euphorbia hirta L., a wild herbaceous plant, is popular in all tropical countries, especially in Vietnam and as widely used in traditional medicine. The HPLC results on the ethanol E. hirta extract from a Vietnamese sample indicated that rutin and quercitrin seemed to be present at concentrations of about 1.06 and 23.80 mg/g extract, respectively. Column chromatography of the methanol extract led to the isolation and identification of two flavonoid glycosides confirming the presence of quercetin-3-O-rutinoside (rutin: EU1) and quercetin-3-rhamnoside (quercitrin: EU2). Antioxidant activity of the crude ethanol extract as well as fractions and the isolated rutin and quercitrin was evaluated based on DPPH and ABTS methods using vitamin C and Trolox as positive controls. The results showed that the half maximal inhibitory concentration (IC₅₀) of the methanol extract by DPPH varied from 1020.7 to 9.1 mg/mL and by ABTS from 160.1 to 9.9 mg/mL while rutin and quercitrin showed the IC₅₀ values of 6.0; 17.3 and 6.3; 13.2 mg/mL, respectively.