Leptospirosis, an acute infectious disease caused by a spirochete of the genus Leptospira following a 10-day incubation period, has not been a reportable disease since 1986. Current surveillance is based on data from the National Reference Center (CNR) for Leptospira, which receives requests for serology from hospital laboratories or biological and medical testing facilities throughout the country. The annual incidence estimated by this system for metropolitan France is low and stable, with an average of 290 new cases per year between 1984 and 2000 (268 cases in 2000, representing an incidence of 0.44 cases per 100,000 inhabitants). The main risk factors identified in a case-control study conducted in mainland France in 1999–2000 were the presence of wounds, canoeing and kayaking, occupational contact with freshwater, and contact with wild rodents. Recently, a working group convened by the French Institute for Public Health Surveillance (InVS) to define priorities in the field of non-foodborne zoonoses (2000–2001) identified leptospirosis as a priority disease. In this context, it was recommended that collaboration with the CNR be strengthened for epidemiological surveillance and for the establishment of an alert system for the human population, as well as the development of a guide for investigating clusters of cases. (Introduction)