This paper deals with the problem of sovereignty in the context of the modern state and its answer to globalization. The reforms that the Republic of Croatia had to make in order to become a member state of two regional organizations, EU and NATO, were investigated. These reforms caused restriction or threat to sovereignty oft he Republic of Croatia because the basic condition for joining a regional organization is the transfer of part of sovereignty to it. Besides, the Republic of Croatia needed to put together its own defense model provided it met the NATO criteria and also implement a series of reforms within political, economic and social structure. All these reforms restricted the sovereignty of the Republic of Croatia. The basic terms, such as globalization, sovereignty and regional organizations are also described int his paper. Globalization also caused the crisis of national states which is most manifested through Brexit and Britain's exit from the EU due to restricted sovereignty and autonomy within the EU. We can also talk about the democratic deficit within the institutions of the regional organizations. Also, globalization has caused a strengthening of resistance to it through the creation of opposing ideologies such as nationalism and populism, a complete turn within its own national borders. The aim of this paper is primarily to prove the restriction of Croatian sovereignty in today's globalized time and how much actually globalization affects the regional organizations and thus the Republic of Croatia.