Fatty acid (FA) composition and isomeric trans unsaturated contents in selected brands of margarines and butter, which are more popular among general consumers of Pakistan, has been reported in this study. A sum of 10 butter and 10 margarine samples, collected from different bakers, confectioners and retail outlets, was analyzed. FA methyl esters were prepared, and quantitative measurements were made using a methyl lignoserate-coated stationary phase, capillary column (SP-2340, 60 m × 0.25 mm, 0.20 μm), with flame ionization detection. The contents of saturated FA, cis monounsaturated FA and cis polyunsaturated FA were in the following ranges: margarines 38.9–53.1, 21.9–35.8, 7.45–21.5% and butter 63.7–68.5, 23.0–27.0 and 1.20–2.94%, respectively. Results showed significantly higher amounts of trans FA (TFA) in margarines ranged from 2.45 to 21.1%, whereas butter samples contained less than 5.00% of TFA.