Between 2008 and 2010 in 106 German organic dairy farms a nationwide interdisciplinary intervention study was carried out in order to develop preventive animal health management strategies for mastitis and metabolic disorders, to validate this concept and to demonstrate its feasibility. During 4 visits per farm, health indicators and influencing factors such as housing, herd management, feeding and forage production were recorded. Following a thorough assessment, farm-individual evidence-based advice was provided by the project team. About two thirds of these farm-individual intervention measures were implemented within one year and their effectiveness in terms of health improvement was monitored for one respectively two years.