The purpose of this investigation was to study the influence of deep fryingfor Farm Frits Potato fingers at 180 ºC on oxidation and thermal degradation in sunflower and soybean oils. Changes in fatty acid composition, refractive index, acid value, peroxide value, thiobarbituric acid (TBA), and polymer content were used to estimate the oxidation and thermal degradation in investigated oils. The changes in fatty acid composition were observed in both of them whereas saturated fatty acid (SFA) increased, particularly palmitic and stearic acid, as well as mono unsaturated fatty acids (MUFA) increased, particularly oleic acid. In contrast, poly unsaturated fatty acids (PUFA) decreased, particularly linoleic acid and linolenic acid, as a result of thermal oxidation, which was produced as oil was exposed to high temperatures through frying, but the rate of change in fatty acid profile in soybean oil was higher than in sunflower oil. Also, results showed that peroxide value, acid value, thiobarbituric acid and polymer content were increased in sunflower and soybean oils but the rate of increment in soybean oil was higher than in sunflower oil. Finally, sunflower oil exhibited high oxidative stability in comparison to soybean oil during deep frying.