Sunflower oil (SFO) seeds of Helianthus annuus L., is a rich source of linoleic acid, which is more susceptible to oxidation of edible oils. Usually antioxidant materials are added to improve the oxidative stability of oils .Mango seeds kernels (MSK) are a sources rich with natural antioxidant compounds. In 2012, the bio-waste was produced by processing industries of mango fruits around 3,932 mT in Egypt. Ethnolic extract of mango seed kernel (MSKE) has been used for stabilization of SFO at three concentrations (mg/kg oil) i.e., 200(MSKE-200), 500(MSKE-500) and1000 ppm (MSKE -1000), while BHT was used at a level of 200ppm (BHT-200) for comparison. Progression oxidation of SFO was followed during accelerated storage at 70°C for 72hr (at intervals of 4hr)by measuring oxidative stability tests: peroxide value(PV), p-anisidene value (P-anv), total oxidation value (TOTOX), acid value (AV) and thiobarbituric acid reactive substances (TBARS) . Results of HPLC analysis of MSKE showed that contained 20 compounds of total phenolic content. MSKE at 100ppm had the highest radical-scavenging activity (96.86%) followed by BHT (94.9%) and ascorbic acid (91.5%). The higher levels of MSKE (1000, 500 ppm) provide the best protection against primary and secondary oxidation of SFO samples. The different parameters of oxidative stability were in agreement with each other, suggesting higher efficiency of 1000ppmMSKE˃ 500ppm MSKE ˃ 200ppm BHT˃ 200ppm MSKE ˃ control.