Unmanned Aerial Vehicles’ (UAVs) operations so far have been mainly connected with military operations and due to security reasons they have been limited to selected space or the space over a real battlefield (the Balkans, Iraq, Afghanistan). Armed forces’ constantly growing requirements concerning the use of UAVs, as well as the increased interest of their application for civil tasks cause that there is a need to ensure UAVs access to controlled and not controlled space (of all International Civil Aviation Organization’s - ICAO classes) and integrate their operations with air traffic control management systems. The problems relating to the development of UAV systems are complex - the works focus on regulations when they are fit for service (certificates), ATM procedures, various technical issues (e.g. propulsion, airframe, miniaturization of radionavigation equipment, remote control and flight control equipment) and defining requirements in relation to the UAV pilot - operator’s qualifications. Multi-sided research is conducted by numerous research and scientific institutions and international aviation organizations (e.g. ICAO, EASA, EUROCONTROL, NATO). Through legislature, it is attempted to reach an appropriate security and safety level - ensuring the UAV flights in ATS space will not create a bigger threat to people and property in the air and on the ground than manned aircraft of the same class and category. Another safety requirement is to develop transparent rules to use the same airspace by unmanned and manned aerial vehicles and complying with air traffic norms, rules and procedures by UAV users, particularly concerning separation and collision avoidance. It is assumed that the way of using UAVs in ATS space must be the same as the one currently used in relation to manned aerial vehicles, i.e. based on rules and regulations set by ICAO. It is forecasted that UAVs will become an important and rightful user of European airspace.