This study was conducted to investigate the nutritional composition and trans fatty acid (TFA) content of some fast foods consumed in Sohag city, Egypt. Furthermore, we studied the effect of using rosemary essential oil (REO) on the TFA content of frying oil. A total of 50 fast food samples were randomly collected from a different restaurants in Sohag city, Egypt. The examined samples were grilled beef burger, fried chicken broast, fried chicken strips, fried beef sausage and fried fish. The samples were examined for moisture, protein, fat, carbohydrate and cholesterol content. Additionally, gas chromatography was used to evaluate TFA content using standard technique. The greatest protein level was found in fried fish samples (22.82%), while the lowest was found in fried chicken strips (14.71%). Fat percentage ranged from 8.4% to 16.2%. Fast foods had a high-calorie value ranging from 215.22 to 329.45 Kcal/100g. Fried chicken broast had the highest cholesterol level which was 79.84 mg/100g. The results demonstrated that fast food had a total TFA concentration ranging from 2.6% to 18.5%. TFA content of the examined fast food exceeded the limits established by WHO as well as FDA regulations. This study showed the nutritional value of Egyptian fast food. However, high TFA content should receive special consideration. REO is an effective natural antioxidant that can be used without harming the sensory aspects of the product.