The aim of this work was to determine the dependence between the content of fatty acids (especially trans isomers) and chemical changes occurring in fats during baking and storage of shortcakes. The fats containing different fatty acids (trans isomers from 4.1 to 53.2%) were used to bake the cakes. The cakes were baked at 180ºC for 20 min and next stored for 6 weeks. Fat was extracted with the Kates’ method and the composition of fatty acids was determined with gas chromatography. It was found that trans isomers content in fats had no statistically significant effect on the oxidation and hydrolytic changes occurring in fats during baking of shortcakes. In all fats, irrespective of the content of trans isomers, the primary and secondary oxidation products appeared in small quantities. Temperature during baking had no influence on the content of saturated fatty acids. Considering trans isomers and polyunsaturated fatty acids in the product in comparison with initial fats, small changes appeared, but the changes were significant from the statistical point of view. Fats with a high content of trans fatty acids - although they do not cause hydrolytic and oxidation changes during baking and storage - should not be used for baking cakes, especially shortcakes with a high content of fat.