The article presents new results of stable isotope analyses made on animal and human bones from the Mesolithic–early Neolithic sites of Lepenski Vir and Vlasac in the Danube Gorges of the Balkans. It reconstructs the food web for the region during these periods on the basis of stable isotope analyses of mammal and fish species found at Vlasac. These results are compared to measurements made on human burials from the two sites. In the light of these new results, the article also discusses interpretations provided by previous isotopic studies of this material. It concludes that great care is required in the interpretation of stable isotope results due to inherent methodological complexities of this type of analysis, and suggests that it is also necessary to integrate stable isotope results with information based on the examination of faunal remains and the archaeological context of analysed burials when making inferences about palaeodietary patterns.