A Computer Network of General Practitioners (GPs) has been established, connecting 150 general practitioners representing a statistically selected national sample, homogeneously distributed all over Italy. The purpose of the network is to increase the epidemiological surveillance on the health status of the Italian community, to collect useful data on the routine activity of the GPs, to promote computer use among them, and to organize some "ad hoc" investigations on specific subjects (case-control studies). To this purpose, a specific software was developed, both to meet the requirements of epidemiological research and to manage general practitioners' clinical files. A working prototype of a health card using micro-computer technology will also be experimented with a subset of the GPs.