Shortly after the Chernobyl nuclear power plant accident the European Commis-sion (EC) initiated various activities in order to make early notification and reliable radiologi-cal information available to the European Union (EU) Member States in case of nuclear acci-dents. The Radioactivity Environmental Monitoring (REM) group at the Institute for Environment and Sustainability (IES) of the Joint Research Centre (JRC) in Ispra, Italy, is responsible for the scientific and technical development of three closely related projects that should be a source of valuable decision support in Europe during major radiological accidents: The European Community Urgent Radiological Information Exchange (ECURIE) system notifies the competent authorities of an accident and promptly informs them about the latest status of the accident and its consequences; The EUropean Radiological Data Exchange Platform (EURDEP) makes radiological monitoring data from automatic monitoring stations in 29 European countries available to all competent authorities in almost real-time; ENSEMBLE produces a comprehensive overview and comparison of the contamination predictions calculated by world leading long-range dispersion models. Starting from the legal background, we describe these information systems in detail with an emphasis on their current status, our experience with them and their planned future develop-ments Keywords: Emergency management, early notification, radiological/nuclear accidents, data and information exchange, atmospheric dispersion. ; JRC.H.4-Transport and air quality