The French-German Initiative for Chernobyl (FGI), implemented by IRSN and GRS from 1997 until the end of 2003, included the “Project on the Radioecological Consequences of the Accident". The most relevant fields of radioecology and post-accidental aspects have been studied. The main goal was to collect and harmonise in NIS countries, the data and results on these topics. These data have been verified, validated and organized in a common georeferenced database REDAC (RadioEcological Database After Chernobyl). For linking the data, topographic maps and maps of contamination by 137Cs have been used and relevant environmental non-radioactive data have been included. The operational database built will also allow the management of the wastes disposal sites. Countermeasures used after the accident have been described and classified. An evaluation of their effectiveness has been done. The database constitutes a tool for the development and validation of operational, assessment and explicative models. This allows the quantification and assessment of radionuclide transfer in the ecosystems. The main parameters influencing the transfers can be identified. REDAC should be completed by further investigations, for example on transuranic elements, and extended to larger geographical zones and combined with others provided by different organisations.