This investigation was carried out to study the extraction of some natural phenolic compounds from by-products of the  rice milling (defatted black rice bran, defatted white rice bran, hull black rice and hull white rice). The extracted phenolic compounds were tested as natural antioxidants compared with synthetic antioxidants (butylated hydroxytoluene (BHT)) using cotton seed oil after deep frying of potato for 25 hours.                 The polyphenols were extracted from by-products of the rice milling using different solvents. The total polyphenolic compounds were identified by HPLC method. The oxidative rancidity of cotton seed oil containing different concentrations of extracted polyphenols (100, 200 and 400 ppm) was estimated by rancimate method. Another set of nutritional experiments were performed to elucidate the extent at which the polyphenols are safe for human being. Several solvents (methanol, ethanol and aceton) were used to extract the natural antioxidants from by-products of the  rice milling (defatted black rice bran, defatted white rice bran, hull black rice and hull white rice). The results indicated that methanol was the best solvent for extracting polyphenolic compounds. However, amount of polyphenolic compounds were as follow: 1050.12, 890.15, 930.50 and 680.25 ppm from defatted black rice bran, defatted white rice bran, hull black rice and hull white rice; respectively. HPLC analysis of total polyphenols extracted from by-products of the rice milling indicated that ferulic acid was the major phenolic compound which identified of defatted black rice bran and defatted white rice bran followed by P-coumaric acid then vanillic acid. While, vanillic acid was the major phenolic compound that presented and identified in hull black rice and- hull white rice extracts followed by p-coumaric acids. The polyphenols extract at level of 400 ppm possessed superior antioxidant effect. Biological assay was conducted on male albino rats using phenolic compounds extract at level of 400 ppm (which consider as a superior concentration of antioxidant) had no effect on liver and kidney activities. In addition, histological examination of rats fed on oils treated with extracts of defatted black rice bran, defatted white rice bran at 400 ppm concentration had no alternations different than those observed in rats fed on control diets.