Background: Several dietary factors are involved in cardiovascular coronary heart diseases, including trans fatty acids, which are generally formed during hydrogenation of vegetable oils, a process that causes conversion of liquid oils into semisolid fats.Nowadays, it is well-known that trans fatty acids form a major risk factor in the occurrence and progression of atherosclerosis. On the other hand, it has been identified that some nuclear receptors, such as PPARs, are involved and play important roles in lipid homeostasis and pathogenesis of cardiovascular diseases. Therefore, we studied the effect of elaidic acid on gene expression of peroxisome proliferator activated receptor gamma (PPARg).Methods: Murine macrophage RAW264.7 cells were treated by 0.5, 1, and 2 mM concentrations of elaidic acid for 6 h. The control group was treated by 50% ethanol (as solvent), equivalent to the amount of ethanol used in 2 mM concentration of elaidic acid. Later, the total RNA was extracted and its cDNA was synthesized. Finally, the quantity of PPARg gene expression was measured by real-time PCR.Results: Overall, 0.5, 1, and 2 mM concentrations of elaidic acid decreased PPARg gene expression in RAW264.7 macrophage cell line by -1.36, -1.68, and -3.24 folds compared with the control group, respectively.Conclusion: By decreasing the expression of nuclear receptor PPARg, elaidic acid causes, intensifies or accelerates the occurrence of cardiovascular diseases, especially atherosclerosis. This finding shows the importance of reducing the consumption of elaidic acid containing foods.