The aim of this thesis is the determination of total fatty acid content in bakery products from Slovenian and Serbian market and quantification of trans-fatty acids. The maximum amount of trans-fatty acids on Slovenian market is 2g per 100 g of total fat content. Two fat extraction methods were compared: Weibull-Stoldt method and extraction by MAK174 kit. The Weibull-Stoldt method gives approximately 25 % (m/m), while MAK174 kit only allows extracting 10 % (m/m) on average. The samples were analysed by gas chromatography with flame-ionization detector. Extract preparation for GC-FID analysis includes derivatization of extracted fat from a sample to volatile methyl esters of fatty acids. The analysis was performed on a highly polar HP-88 column, which allows separation of fatty acid methyl esters according to the length of chain, unsaturation, cis/trans isomerization and the double bond position. Compounds in the samples were identified based on retention times acquired with a previously optimized chromatographic method, which allows a better separation of C18:2 and C18:3 fatty acids. Quantitative determination, which includes sample preparation as well, has a great repeatability.