In this graduation thesis entitled: "The role of international intelligence services in the national security of states" the influence of international intelligence services on the national security of a particular state is defined. Security is a prerequisite for the survival of man, society and the state. The increasing need for security resulted in the emergence of security and intelligence services. Intelligence services are organizations that collect and analyze information about potential threats that pose a danger to national security. They play a key role in protecting national security. National security can be defined as a state of protection of the fundamental values of society. The thesis defines the intelligence services in Croatia and the most important international intelligence services. The very goal of the thesis is focused on the subject of the graduation thesis, and it refers to gaining insight into the relations between international intelligence services and the national security of a particular state. The above examples provide an insight into the positive and negative impacts of international intelligence services. The work of the intelligence services is shrouded in secrecy, so the amount of information about them is limited. Studying the above examples, it can be argued that with the progress of the world, the need for security is increasing, but it is necessary to establish a balance between freedom and security.