In 1998, the European Community, the Region Wallonne, and the Province du Hainaut funded the project known as the Centre for the control of animal health and its management (CESAM). This project was initiated in the Hainaut province of Belgium to answer problems encountered by cattle producers. Its overall goal is the identification of stages in the entire bovine production process where economic efficiency can be increased. A part of this project aims principally at the study of the impact of health-related problems on dairy production. For this part of the project, 32 veterinarians and 51 farmers started collecting data in the field. The methodology for data collection was based mainly on the harmony between the farmer and the veterinarian. Therefore, several procedures were implemented to ensure adequate motivation of both farmers and veterinarians. Farmers note all events of their livestock using a list, which contains disease events, preventive treatments, reasons for culling, and management practices. A veterinarian visits farms monthly to validate collected data and to discuss specific problems. During these farm visits, veterinarians collect body condition scores on adult cows. Veterinarians record also information on health problems they encounter during their normal practice using an international health data recording nomenclature. A national organization provides unique animal identification system. Production data will be recorded and feeding practices, milking procedures and barn comfort indices will be regularly investigated. All data will be collected on pre-printed documents, scanned at CESAM and centralized in a relational computer database. Criteria to evaluate the quality of the proposed methodology are presented.