No nuclear power station are operative in Italy as a consequence of the general public debate on the use of nuclear energy, stressed by the Chernobyl accident and culminated in the Public Referendum in 1987, but within a distance of a few hundreds kilometers from its border several nuclear plants are operating. In case of a nuclear emergency, for instance, an accident in a transboundary plant, ANPA, National Agency for the Environmental Protection, as the duty to coordinate the technical activities supporting the Civil Protection Agency responsible for the management of national-scale radiological emergency. In this context, the realisation of the ANPA Environmental Radiological Surveillance System was started in 1996. The system was designed for continuous monitoring and early warning purposes and then the airborne particulate was selected as main environmental matrix to be observed. The system is composed of two natio-wide monitoring networks connected to the control centre operating at the ANPA’s Emergency Centre; measurements, alarm signals and system status informations are transmitted to the centre in real time for data evaluation, reporting and recording into a data-base and for remote diagnostics of the monitoring station functioning. The ANPA Environmental Radioactivity Surveillance System will be described emphasizing the characteristics of automatic monitoring network.