The aim of this paper was to determine the influence of fat addition, in dependence of trans isomers of fatty acids content on chosen quality features of puff-pastry cakes with different flour. The quality of six 100% vegetable fats was determined. Examined fats differed in fatty acids composition, especially in trans isomers content (from 4,1 to 54,2%). The fatty acids content in fats was determined using a gas chromatography. Two flour were used, one with higher (IG = 34) and other with less gluten index (IG=49). Quality of puff-pastry (volume, sensory parameters) were determined after 24 hours after baked. On base of carried research it was claimed that increase of trans isomers content has not effected in significant way on the puff-pastry cakes with flour with less gluten index. Increase of trans isomers content has no influence on volume improving of puff-pastry cakes with flour with small gluten index. During application of fats containing trans isomers (from 9,9 to 27,7%) better sensoric values of puffpastry cakes with flour with small gluten index were noticed in comparing to cakes with high gluten index.