The risk factors associated with mortality in Legionnaires' disease remain poorly documented. Method: A retrospective analysis was conducted of Legionnaires' disease cases reported in France through mandatory reporting between 2002 and 2004. We compared fatal cases of Legionnaires' disease with non-fatal cases using a logistic regression model. Given the significance of age, we distinguished between individuals under 60 years of age and those 60 years of age and older. Results: Three thousand two hundred sixty-seven cases were reported. The outcome was known for 85% of them (2,791), including 377 deaths (13.5%); 72.5% of the patients were men (median age = 61 years). Multivariate analysis identified the following factors associated with mortality in those under 60: cancer or a blood disorder (OR = 6.4, 95% CI 3.6–11.2), kidney disease (OR = 3.2, 95% CI 1.0–9.9), and chronic alcoholism (OR = 2.2, 95% CI 1.1–4.4). For those over 60, these same factors appear to be associated with mortality (cancer or blood disorder: OR = 1.8, 95% CI 1.2–2.6; kidney disease: OR = 3.0, 95% CI 1.4–6.4; chronic alcoholism: OR = 2.4, 95% CI 1.2–5.2). Furthermore, cardiac disease (OR = 2.4, 95% CI 1.4–4.0), immunodeficiency (OR = 1.7, 95% CI 1.1–2.6), nosocomial Legionnaires’ disease (OR = 2.0, 95% CI 1.3–3.0), or Legionnaires’ disease contracted in an institution (OR = 2.4, 95% CI 1.6–3.6) were factors associated with mortality. Conclusion: These preliminary results have helped clarify the factors associated with mortality from Legionnaires' disease in France and should be supplemented by prospective studies. Mortality remains high, and it is important to better identify the patients at highest risk in order to provide appropriate care.