This study evaluated the antioxidant and antiproliferative activities of the crude extract and fractions of Desmodium triflorum (L.) DC. The total phenolic content, 1,1-diphenyl-2- picrylhydrazyl hydrate (DPPH) free radical scavenging activity, trolox equivalent antioxidant capacity (TEAC), reducing power, total flavonoid content of D. triflorum were evaluated for the exploration of its antioxidant activities. Furthermore, its antiproliferative activities were investigated through the MTT method. It was compared with the antioxidant capacities of known antioxidants, including catechin, alpha-tocopherol, trolox and ascorbic acid. Among all fractions, ethyl acetate fraction was the most active in scavenging DPPH and TEAC radicals, of which 0.4 mg was equivalent to 186.6 +/- 2.5 microg and 82.5 +/- 2.1 microg of alpha-tocopherol and trolox respectively. The total phenolic and flavonoid contents of the crude extract were equivalent to 36.60 +/- 0.1 mg catechin and 45.6 +/- 0.6 mg rutin per gram respectively. In the reducing power assay, 1.25 mg of crude extract was similar to 61.2 +/- 0.3 microg of ascorbic acid. For the assessment of the safety and toxicity of D. triflorum, LD(50) of the crude extract was greater than 10 g/kg when administered to mice through gastric intubation. The above experimental data indicated that D. triflorum was a potent antioxidant medicinal plant, and such efficacy may be mainly attributed to its polyphenolic compounds.