Modern warfare, including the Ukraine-Russia war, relies heavily on disinformation. Fake news on social media is an integral part of this. At the same time, each conflict is characterised by distinct communication specificities and in the context of the complex effects of fake news, questions arise about their specificity for a given conflict. The aim of the presented research was to answer the question of what the various fake news about the Russian-Ukrainian war disseminated in Polish-language social media have in common and what narrative they generate. The analysis covered the construction of the messages as well as their contexts: social, cultural, historical, and political. For this purpose, a three-stage analysis of ten fake news cases disseminated between March and September 2022 was conducted, applying a three-element analytical matrix. The research made it possible to identify the properties of fake news, generated narratives, and their possible effects.