In 1995, a working group coordinated by the Directorate General for Health and the National Public Health Network (RNSP) reviewed strategies for the surveillance of infectious diseases. The evaluation of Legionnaires' disease surveillance in France was identified as a priority. A study conducted by the RNSP and the National Legionella Reference Center, in collaboration with hospital laboratories, estimated the total number of Legionnaires' disease cases diagnosed in France in 1995 at approximately 530. This study highlighted current gaps in the mandatory reporting system for Legionnaires' disease. (adapted from the text).