Tomato peel was treated by ethanol 70% (v/v) to extract flavonoids (kaempferol, quercetin, lutolin, narginine and rutin) and phenolic acids (P-coumaric, ferulic and chlorgenic acids) were identified by paper charomatographic technique. Natural and synthetic (butylated hydroxyanisol, BHA) antioxidants exhibited strong and close antioxidative activities 85.85 and 92.60%, respectively. The tomato peel extract and BHA were added to sunflower oil at levels 100, 150 and 250 ppm to keep its quality during heating at 1800C for 32 hours. Moreover, the natural and synthetic antioxidants were added to cake made up by sunflower oil at the same levels. Cake was stored at room temperature for four weeks and the lipids were extracted every four days. The results showed that the addition of tomato peel extract as natural antioxidant to sunflower oil and cake delayed the lipid peroxidation during heating oil and storage of cake.