MedNet is the very broad-band seismorgraphic network installed by the Istituto Nazionale di Geofisica (ING) in countries of the Mediterranean area, with a final goal of 12-15 stations and a spacing of about 1000 km between stations. The project started in 1987 and will be completed within 1992. MedNet is motivated both by research interest and by seismic hazard monitoring; it will allow to define the structure of the Mediterranean region to a high detail, to study properties of the seismic source for intermediate and large events, and to apply this knowledge to procedures of civil protection. To reach its goals, the network has been designed following the highest technical standards: STS-1/VBB sensors, Quanterra 24 bits A/D converters with 140 dB dynamic range, real-time telemetry. Five sites are now operational in Italy (L'Aquila, Bardonecchia and Villasalto) and in northern African countries (Midelt, Morocco; Gafsa, Tunisia); other sites are under construction in Pakistan (Islamabad), Irak (Rutba) and Egypt (Kottamya), while locations are examined for stations in Greece, Jugoslavia and Algeria. The centre of the MedNet network is the Data Center (MDC) in Rome; its tasks include data collection, verification, quality control, archival and dissemination, monitoring of station performance, event detection, routine determination of source parameters. Data distribution will follow the guidelines set by FDSN, and will be coordinated with other international network projects.