The hydro alcoholic extract of leaves of Lagerstroemia speciosa (LS) was studied for antioxidant activity on different in vitro models namely 1,1-diphenyl, 2-picryl hydrazyl (DPPH) assay, Hydrogen peroxide and Nitric oxide radical scavenging method, and superoxide readical scavenging by alkaline DMSO method. Various standards were also evaluated for comparison. The extract showed dose dependent free radical scavenging property in the tested models. Lagerstroemia showed IC50 value 4.75±0.25 μg/ml for DPPH method, which was comparable to that of ascorbic acid (IC50=2.75±0.29 μg/ml) and rutin (7.89±0.51μg/ml) . For Hydrogen peroxide method, IC50 value was found to be 28.00±0.16 μg/ml, which compares favourable with Ascorbic acid (IC50=187.33±3.45μg/ml) and rutin (35.26±0.166μg/ml). In Nitric oxide model, IC50 value was found to be 750±3.66μg/ml, which is very low when compared to Rutin (IC50=68.5±2.27μg/ml). This study demonstrates the antioxidant activity of the Lagerstroemia speciosa.