The effect of extracted cinchona bark (Cinchona calisaya), garden cress (Lepidium sativum), thyme (Thymus vulgaris) andginseng (Panax ginseng) as natural antioxidants were investigated. The effect of those extracts to prevent or limit the rancidity rate of sunflower oil comparing with butylated hydroxytoluene (BHT) as synthetic antioxidant. Obtained results showed that the cinchona bark had the highest content of total phenolic compounds and antioxidant activity (6763.2 mg/100gm and 89.81%), while ginseng had the lowest content of total phenolic compounds and total antioxidant activity (796.38 mg/100g and 49.41%). Elagic and catechin were the most phenolic compounds in cinchona bark (121.78 and 101.07 mg/100g, respectively), while garden cress had the highest content of coumaric acid comparing with other compounds which were 40.28 mg/100g. Gallic and benzoic acids were the most demonant phenolic compounds in thyme (67.19 and 72.33 mg/100g, respectively). Results also indicated that, adding 2000ppm of cinchona bark extract and 200ppm BHT to sunflower oil gave the same antioxidant effect (about 96%) and had the highest effect as antioxidant than that of either tested extractions. It was also clearly observed that adding 2000 ppm of thyme extract gave an antioxidant activity (91.25%), while, the lowest effect for antioxidant was recorded by adding 2000ppm ginseng extract (54.80%). The rancidity test explains that the highest stability of sunflower oil increased with adding cinchona bark extract (2000ppm). It reached to 5.84h (8.76 months) while the lowest stability was 5.00h (6.98 months) at 2000ppm with supplemented of extracted ginseng. Garden cress and thyme extracts recorded the moderate stability which was 5.6h (8.26 month and 5.76h (8.51 months), respectively.