Species of the genus Acmella are perennial plants and are well known as traditional medicines and as vegetables in tropical regions. Of these, A. oleracea (L.) R.K. Jansen is the most widely used, and is cultivated as an ornamental plant and as a crop. In traditional medicine, it is used for the treatment of haemorrhage, helminthiasis, gingivitis, laceration, malaria, oral and gastric ulcer and infections, dysentery, urinary calculi, and inflammations. Biochemical tests of the methanol indicated presence of important bioactive compounds, such as phytosterols, and tannins. Assessment of the free radical scavenging activity showed that it has concentration-dependent antioxidant activity similar to that of the standard butylated hydroxytoluene (BHT). The half maximal inhibitory concentration (IC50) of the plant extract was 13.773 mg/ml, while it was 28.098 mg/ml for BHT. The total antioxidant activity was 85 mg/ml calculated against the standard ascorbic acid. The total phenol content was estimated using Folin-Ciocalteu-gallic acid reaction, and was determined to be 1.38 GAE mg/g. Using the aluminum chloride-quercetin assay, the total flavonoid content was calculated to be 28.7 QE mg/g. Keywords: A. oleracea, antioxidant activity, total phenol, total flavonoid.