Emerging challenge concerning public health statistics is the ability to provide real time information on population health. It is especially relevant in case of emergency scenarios: pollution through toxic gas emission or radioactivity, heat waves, pandemic flu viruses. The daily improvement of care practice can also benefit of any real time information on patients hosted in medical structures. To face this problematic, the french GINSENG project uses the european grid technology to create a sentinel network for e-health and epidemiology. This distributed network architecture offers many advantages: * Medical data banks from each hospital or labs can be interrogated directly without centralizing any information * Such architecture is then really cost effective. * Statistical studies will be soon available in real time through a web interface accessible by the medical staff. While patient data consistency can mainly be achieved by working on medical databases standardization, patient identification and medical data linkage mechanisms are performed dynamically through the grid network. Authentication and data encryption are ensured by healthcare professional smartcards containing an X509 grid-compatible certificate delivered by a trusted certification authority. The GINSENG project focuses on two fields: cancer surveillance and perinatal health.