The aim of this article is to analyze the causes of migration to Europe and ways to protect the eastern border of the Republic of Poland against illegal migration. The geopolitical situation in the world has caused a sharp increase in illegal migration. This is not a new phenomenon, as climate change and armed conflicts that have been going on for many years are intensifying this phenomenon. Poland's eastern border is also the eastern border of the European Union. To a large extent, the protection of the eastern border against illegal migration not only affects the security of the Republic of Poland, but also protects the entire EU against this practice. The main research problem was formulated as follows: What security measures should be used to ensure protection of the eastern border of the Republic of Poland against illegal migration? The basic method used in preparing the publication was the analysis and synthesis of collected scientific sources. A comparison was also used, the essence of which was to identify common features, similarities and differences in existing threats related to illegal migration. The use of this method allowed for the detection of similarity and dissimilarity in securing the state border by referring to border protection systems as well as the experiences of other countries. Moreover, inference was also used to formulate the most important results of the diagnosis. After Poland's accession to the Schengen area, the Border Guard is responsible for protecting the external border of the European Union with the Russian Federation, Belarus and Ukraine. It also conducts activities related to combating organized crime and illegal migration in the territory of the Republic of Poland. Developed international cooperation is one of the basic elements determining the effectiveness of border services, hence the Border Guard attaches great importance to its improvement. Ongoing cooperation of the Border Guard with border services of neighboring countries is an essential requirement for border protection. This cooperation is implemented at all levels of command and also takes institutionalized forms. It is assumed that an integrated border management system is a key issue in counteracting illegal migration. This process provides comprehensive and consistent control in the area of EU security, which allows us to respond to identified threats in a more effective and efficient manner.