According to the CDC approximately 76.8 million American adults are obese; a medical condition that costs the United States $147 billion dollars annually. One of the factors thought to be contributing to this growing epidemic is the over consumption of trans fats in today’s formulated foods. According to the FDA’s definition, trans- fatty acids are unsaturated fatty acids that have one or more of their double bonds changed from the cis- to trans- orientation. Hydrogenated oils are unsaturated oils that are stabilized to improve the shelf life of foods, but this process can sometimes produce trans- confirmations. The goal of this study is to investigate the trans fat content of commercial french fries before and after final frying in fresh, medium and heavily used soybean oil. To determine trans fat content in commercial fries before and after final frying, fries were crushed and placed in hexanes. After the extraction, methyl ester derivatives were synthesized by reaction with potassium hydroxide and methanol. The extracts were separated and analyzed by gas chromatography-mass spectrometry and high pressure liquid chromatography.