Challenges in the area of disinformation are not a new phenomenon for Poland and Ukraine, but the intensification of relations between the two countries related to the outbreak of war in Ukraine has definitely intensified them. The aim of the article is to analyze Russian disinformation activities since the outbreak of the war, which have been aimed at Polish-Ukrainian relations. The following research question was posed in the work: How is the Russian disinformation affecting Polish-Ukrainian relations changing after the outbreak of war in February 2022? Based on the conducted scientific query, analyzing the available literature and Internet studies, as well as using the scenarios implemented so far by Russian propaganda, the following hypothesis was adopted: Russian disinformation activities detrimental to Polish-Ukrainian relations will progress along with closer political cooperation and migration from Europe East to west of the continent. The article presents examples and analysis of anti-Ukrainian disinformation narratives that have gained great popularity since February 24, 2022. Due to the dynamic international situation, the amount of information appearing in the public space makes it difficult to control and verify it. The tightening of Polish-Ukrainian relations is a significant challenge for Russian disinformers, who will use further examples of cooperation and solidarity of both countries for their purposes. Among the popular motives of disinformation, historical resentments were singled out, which in particular refer to the Volhynian massacre. The aim of the research is to identify the narratives that have hit Polish-Ukrainian relations, especially in recent months. The research was carried out almost for a year, from the beginning of the Russian invasion of Ukraine. The authors mainly analyzed scientific studies, including historical ones, press releases, reports and posts in social media. So far, the activities of Russian disinformation, which has a negative impact on Poland's cooperation with other countries, have been investigated to a limited extent. Therefore, it is crucial to verify emerging challenges on an ongoing basis, and the article also points to new trends in Russian disinformation, which has begun to include a preventive element, referring to the campaign against Poles who sympathize with Ukraine.