Background. A child with elevated blood lead levels was identified in Réunion as part of the screening program for childhood lead poisoning conducted in 2008–2009 by the Institute for Public Health Surveillance. Until then, cases of lead poisoning in Réunion had been rare: only about ten cases were reported in the 1980s, all in adults, linked to the use of lead-containing mortars for food preparation. Methods. Screening was offered to the family of the index case, and an initial environmental investigation was conducted using a standardized questionnaire. Screening in the vicinity of the case and soil sampling outside and in the immediate vicinity of the home were then carried out. The environmental investigation was supplemented by soil sampling extended to the entire neighborhood, and information was provided to resident families (87 households and 287 individuals), encouraging screening of children under six years of age and pregnant women. Results. The index case lived in the Oasis neighborhood, a slum area in the municipality of Le Port. The results of the soil analyses revealed the presence of heterogeneous and superficial lead contamination throughout the Oasis neighborhood, with a maximum value (5,200 mg/kg) exceeding 300 times the background level found in natural soils on Réunion. Screening identified 76 cases of childhood lead poisoning (blood lead levels of 100 mg/L or higher) among the 148 individuals tested (51%). All cases involved children under the age of 15. The median age of the cases was 5.6 years. The median blood lead level was 196 mg/L (range 102–392 mg/L). Conclusion. The primary hypothesis put forward to explain soil contamination in the Oasis neighborhood is the presence of illegal waste dumping (used vehicle batteries), as well as widespread metal recycling activities. Steps have been taken by public authorities to remove all families in the neighborhood from environmental exposure to lead by ensuring their rapid relocation outside the area.