This investigation was carried out on the dried orange peels. High dietary fiber content was prepared from orange peels. The dietary fiber composition, total phenolic compounds and antioxidant activity of dried orange peels were studied. Methanolic orange peel extract as a natural source of antioxidant was evaluated during 6 months storage of refined sunflower oil at ambient temperature. The total dietary fiber content in orange peels was 70.95%, with an appreciable amount of soluble fiber (21.64%). Insoluble dietary fiber was the predominant fraction in orange peels (49.31%). The studied orange peels contained the best ratio of soluble/insoluble fractions (1.0- 2.28). The total phenolic compounds in dietary fiber were 21.24 mg/g. The antioxidant activity of total extractable polyphenols was studied, using β-carotene/linoleic acid antioxidant assay. The polyphenols showed high antioxidant activity, largely preventing the bleaching of β-carotene which indicates a good capacity for reduction of the radicals generated by the oxidation of linoleic acid. Antioxidant activity of methanolic orange peels extract was assessed by measuring free fatty acid content, peroxide value and iodine value during 6 months storage of sunflower oil containing 2000 ppm orange peel extract. The treated samples showed lower FFAs content (0.968%) and PV (4.71 meq/kg-1 ) and higher iodine value (98.0) compared to control sample. Therefore, the use of orange peels extract is recommended as a natural antioxidant to suppress development of rancidity in oils and fats