Abstract: Oxidative stress is inevitable. Preventive actions should be taken to minimize the oxidative damages to biomolecules which may lead to health problems. Murraya koenigii leaves are reported to possess potent antioxidant properties. This study was initiated to evaluate the Total Phenol Content (TPC) and Antioxidant Activity of aqueous extracts of M. koenigii. Leaves were dried to constant weight, powdered and sieved. TPC was estimated in the cold and hot aqueous extracts of the M. koenigii leaf powder stored at room temperature and at 4oC in monthly interval for six months. The initial TPC of cold and hot extracts of Murraya koenigii leaf powder was 22.6 and 25.08µg TAE/g dry weight respectively. When the Murraya koenigii leaf powder was stored at room temperature for 6 months, TPC of cold and hot water extracts was 11.02 & 11.71 µg TAE/g dry weight respectively while the TPC of cold and hot water extracts of the leaf powder stored at 4oC for six months respectively was 12.31 & 12.84 µg TAE/g dry weight. Extraction of antioxidant activity was better with hot water than with cold water. TPC of Murraya keonigii powder decreased when stored both at room temperature and at 4oC. Both cold as well as hot extracts exhibited antioxidant activity even after storing for 6 months. At 3 months the decline in the TPC of the powder stored at Room temperature is higher than that stored at 4oC. In the Siddha Medicine the lifespan of ‘Chooranam’ which is prepared from herbs is used for 3 months. Hence the leaf powder can be used for the ‘Chooranam’ preparation. However freshly prepared leaf powder is recommended for the preparation of the ‘Chooranam’.