Antioxidants are substances that may protect cells from the damage caused by unstable molecules known as free radicals. Because of potential health benefits of natural anti-oxidants they are expected to be an alternative to synthetic ones. The studies also showed that some medicinal plants possessed more potent antioxidant activity than common dietary plants. In this present study the methanolic extract of whole plant Oryza sativa were investigated by using DPPH scavenging test and reducing power method. The preliminary phytochemical screening was performed and the total phenolic content had been estimated. preliminary phytochemical Analysis of methanolic extract of Oryza sativa plant revealed the presence of Poly phenols, glycosides, carbohydrates and proteins. The total phenolic content was found to be 172 mg quercetin per g weight of extract. The MEOS exhibited a significant dose dependent inhibition of DPPH activity. The IC50 values of the MEOS and reference standard ascorbic acid were found to be 30 µg/mL and 37 µg/mL respectively and the similar activity was shown in the other method also.