Clinical and epidemiologic studies showed that among dietary factors the type of fatty acids (FAs) in the diet plays an important role in determining risk of chronic disease. The aim of our study was to determine the levels of Trans FA (TFA) in edible oil samples consumed in Tehran, Iran analyzed by gas chromatograph (GC). The mean of total TFA was 0.45% ranging from (0.11% - 1.61%) for liquid frying oils and 2.92% ranging from (0.46% - 5.40%) for solid oils. The major TFA observed in these two groups was elaidic acid in solid oils. The highest content of total saturated fatty acid (SFA) was detected in solid oils with average of 32.07 and palmitic acid was the major SFA in these four groups. Linoleic and linolenic acid are the most important poly unsaturated fatty acid (PUFA). The variance in the percentage of TFA in the edible oils probably resulted from differences in the type of oils, quality, heating, processing technique and storage condition of the edible oils. The results indicated that, edible oils contain considerable proportions of trans fatty acids. Therefore, it is important to assess the content of TFA in edible oils in Iran.