DIPNET (Disease Interaction and Pathogen exchange Network) is a co-ordination action funded under the UE Framework programme 6 priority 8 Scientific Support to Policy (SSP). The principal objective of DIPNET is to increase scientific knowledge of the potential transfer of pathogens and diseases between wild and farmed fish and shellfish populations. DIPNET started in October 2004 and is a 2 year project. The project is organized in four work packages. Work package (WP) 1 is focused on a literature review of disease interactions and pathogen exchange between farm and wild aquatic animals. This analysis includes both published and unpublished literature. The work covers a wide range of habitats and species within Europe and, where relevant, world-wide. WP1 is divided into 4 subgroups, covering successively the North Atlantic Scenario, the Continental European Scenario and the Southern European Scenario for fish, and the Shellfish Scenario for crustaceans and mollusks. Risk assessment and modelling studies in the area of aquatic health are critically reviewed in WP2. In particular, studies of disease interaction are scrutinized to determine how risk assessment or modelling contributed to the analysis of disease interaction. In WP3 a review critically examines the currently used methods in monitoring and surveillance activities on farms, rearing areas and harvested and wild stocks in Europe. An optimized epidemiological methodology will be proposed taking recent advances in the surveillance of terrestrial diseases into consideration. Two seminars will be organized later in the project targeted at potential users, one on risk assessment methods, the second on epidemiological methods. WP4 is focused on network building and knowledge dissemination. Newsletters are published twice a month and are available at the following address (http://www.dipnet.info/). WP5 is devoted to the scientific project co-ordination and liaison with the policy-makers of the European Union.