The Schengen regime is one of the most concrete achievements of the European Union, which enables the free movement of people, goods and services within the borders of the European Union. The erasure of internal borders has consequently shown the need to strengthen the external borders of the Schengen area. At the same time, the Schengen Agreement enabled the establishment of emergency and temporary controls at internal borders, and one of the situations that triggered this possibility occurred in 2015 during the migrant crisis caused largely by the war in the Middle East. The migrant crisis led to a major crisis in the functioning of the Schengen regime, but also collapsed the security order of the European Union, which then suddenly faced a large wave of refugees on its territory. The Schengen regime has proved extremely ineffective in tackling the consequences of the migrant crisis, but an even bigger problem has been the lack of a common stance at EU level on finding a common solution to stop illegal migration and agreeing on the distribution of migrants and their integration into society. Although EU Member States need a certain number of immigrants, they have shown that they do not have ready and feasible strategic plans for accepting large numbers of migrants, and were clearly not prepared for the high security risk posed by the uncontrolled arrival of immigrants in the EU. The subject of the research analysis is the relation within the Member States on the issue of illegal migration and the future role of the Schengen regime in order to increase the security of the European Union. It also explored how member states protect the Schengen regime at the external borders, especially on the migrant route, and how Croatia defends the EU's borders in an effort to enter the Schengen area.