The aim of the study was to determine the possibility of reducing fat content in fatty sponge-cake products by addition of inulin. 200 g/kg, 440 g/kg, 680 g/kg and 100% of fat was substituted with 20 g/kg, 35 g/kg, 50 g/kg, and 62.5 g/kg of inulin , respectively. The authors used two types of fat: with low and high content of trans isomers – containing 2.1 g/kg and 511.2 g/kg of fatty acid methyl esters (FAME), respectively. An analysis of crumb quality and the evaluation of sensory discriminants were undertaken. It was demonstrated that it was possible to substitute fat with inulin in fatty sponge-cake products. However, in the case of fat with a high content of trans fatty acids (TFA), its substitution even with higher amounts of inulin had a smaller impact on the qualitative parameters of products than in the case of fat without TFA. Substitution of fats with inulin allows for eliminating dangerous TFA, reduces energetic value of food products, and simultaneously enriches them with nutritionally-valuable oligosaccharides. Furthermore, products without the addition of inulin-based fat can be an alternative to conventional fatty sponge-cake products and a factor that supports prevention in many food-related and other diseases.