Antioxidant activity of methanolic extract of Couroupita guianensis flower was studied for its free radical scavenging property on different invitro models e.g.-1, 1-diphenyl-2-picrylhydrazyl (DPPH) method, hydrogen peroxide method and total antioxidant method. All the antioxidant activities were compared with standard antioxidant ascorbic acid. The values of the methanolic extract of Couroupita guianensis flowers were found to be 67.3±0.4μg in DPPH assay, 62.5±1.2μg in hydrogen peroxide model and 55.9±1.9μg in total antioxidant activity model at the concentration of 200μg/ml. It was concluded that couroupita guinensis flower possessed a strong antioxidant activity in the method of DPPH radical scavenging activity