In May 2010, the Nancy Hospital Center reported to the Lorraine-Alsace Regional Health Agency three cases of acute lymphoblastic leukemia that had occurred within less than two years among children attending the same school in Amnéville (57). The Cire launched an investigation following the ad hoc protocol, which had the following objectives: - to determine whether there was an excess of the disease in the population; - if such an excess was observed, to determine whether one or more causes other than chance could explain it. The investigations indicated an excess of leukemia cases among children under 15 years of age attending school in the municipality of Amnéville. They confirmed the absence of individual risk factors for the cases and of any common exposure other than attending the same school. Hypotheses regarding exposure to risk factors, other than atmospheric benzene, during the 2003–2010 period were ruled out. It was not possible to precisely characterize exposure to atmospheric benzene for the period prior to 2008, due to persistent uncertainties surrounding the estimation of past exposure. The data collected appeared to indicate the absence of any exceptional exposure situations. Given this situation, the Cire recommends continuing prospective surveillance of childhood leukemia cases for three years. Since advancing knowledge on risk factors falls within the purview of research programs, the French Institute for Public Health Surveillance (InVS), as a co-funding body of the GEOCAP study, will request that this study also assess, if possible, the influence of industrial sites producing benzene on the occurrence of childhood leukemia. (R.A.)