Improving animal health status at herd level relies on the identification of the most effective and efficient control measures considering the complexity of farm specific conditions. The FP7 project IMPRO (impro-dairy.eu) proposes the use of the Impact Matrix (Vester, 2007) as a novel tool for the identification of farm specific opportunities and constraints in animal health management of organic farms across Europe. Identifying relevant variables affecting animal health is the first step in performing the Impact Matrix and the aim of this study. Five workshops gathering a total of 80 experts in animal health on organic dairy farms (farmers, advisors, veterinarians, researchers, and members of dairy associations and the dairy industry) were held in France, Germany, Spain and Sweden to obtain variables through a systemic analysis of the organic dairy farm system. Areas relevant to animal health at the farm level were identified by applying participatory methods. Aggregation and structuring led to the nomination of systemrelevant variables whose exact meaning was defined and further explained by a list of indicators. The 4 national lists, exhibiting a great congruence between the total of 81 variables, were deliberated further by a multi-national team of researchers. A pan-European list of 20 variables was established. The following fields (and the number of variables reflecting them) were identified to influence animal health: regulations (1), financial and labour resources (2), farmers’ skills, quality of health monitoring and control (3), availability of advisers (1), genetic potential (1), cow environment (1), adequacy of the diet (3), management of different age groups (2), animal performance related to milk production, reproduction and health (3), preventive measures and treatments of diseases (3). The participatory, bottom-up approach was successful in deriving a set of variables covering the variation not only between different farms but also between countries. The obtained variables are the key components of the Impact Matrix and will be used on organic dairy farms to assess opportunities and constraints regarding the improvement of animal health. It is our hypothesis that this analysis of the farm system could help the farmer and his advisors to design effective health control plans.