The GINSENG (Global Initiative for Sentinel E-health Network on Grid) project aims to implement a grid infrastructure for ehealthand epidemiology in Auvergne. A distributed medical database is created upon a secure network for epidemiologicalstudies. Our goal is to create a decentralized information system using grid technologies. The medical sites involved in theproject are clustered around two themes: cancer monitoring and perinatal care. On each medical site a server whichduplicates the medical database, is deployed with grid services. At the same time, full control of the information is kept by theorganizations storing patients' files. This solution allows for a high level of security, privacy, availability, and fault tolerance.Queries made on the distributed medical databases are made via a secure web portal. Public health authorities use thisinfrastructure for health monitoring, epidemiological studies and evaluation of specific medical practices.