In France hospital bed capacity is determined according to a national and regional authorization which has been established by the regional hospital agency. The bed capacity evolution in a hospital is fixed by considering the different proposals of the hospital in negotiation with the regional hospital agency. Types of beds are differentiated according to the patients' needs : medicine, surgery and obstetrics. The first approach is taken at the national level and then at the regional level using a specific ratio of beds for 100,000 inhabitants in each category. For a given hospital, the authorized number of beds takes into consideration their occupation. Target bed occupation ratios were fixed in 1992 and are still in use. In the establishment project of the University Hospital of Nancy (developed over a five year period) four approaches have been formulated and their results have been compared. In this study, the two traditional methods of bed ratio per 100,000 inhabitants and target bed occupation have been updated according to the present conditions of hospitalisation; the third method is based on the reapportionment of the present patients and the possible risk to the hospital for refusing patients. The last method consists of determining the expected pathologies five years in advance in Lorraine and the beds needed to treat them. These four methods have given consistent results under the accepted revised target occupation bed ratios in accordance with the reduction of the length of stay between 1992 and 1999.