In mid-July 2001, three biologists and a general practitioner from the Aveyron region reported to the DDASS an unusually high number of cases of Salmonella Enteritidis infection that had been observed since early June 2001. Epidemiological investigations were launched to identify the origin and source of the outbreak and to propose appropriate control and prevention measures. Cases were identified through public and private laboratories in the departments of Aveyron, Cantal, and Lot, as well as the National Reference Center for Salmonella and Shigella. Two controls, selected at random from the telephone directory, were identified for each case within the same municipality of residence. Cases and controls were interviewed by telephone using a standardized questionnaire. The supply chains of the stores where cases had purchased the suspected food item were traced using the list of suppliers. Strains of human origin and those isolated from the implicated food item were characterized by lysotyping and compared using DNA macro-restriction analysis. From June 1 to July 31, 2001, 190 cases of Salmonella Enteritidis infection were identified during an initial outbreak in the departments of Aveyron, Cantal, Lot, Corrèze, and Tarn-et-Garonne. Case-control studies showed that consumption of young Cantal cheese (< 2 months of aging) was significantly associated with the disease (OR = 11.2; 95% CI 2.6–66.2). Analysis of the distribution and supply chains of the cases’ points of purchase identified a cheese producer “A” common to all the cases’ points of purchase. Analyses conducted on cheeses sampled from stores and from the implicated producer “A” tested positive for Salmonella Enteritidis. The human-derived strains and those isolated from Cantal cheese belonged to lysotype PT8 and exhibited an identical DNA macrorestriction profile. A second outbreak of 25 cases of Salmonella Enteritidis salmonellosis occurred from October 15 to 31, 2001, in the Aveyron department. The case-control study showed that only the consumption of young Cantal cheese was significantly associated with the disease (OR = 4.1; 95% CI 1.1–15). The majority of human-derived strains studied belonged to the PT8 lysotype and exhibited the same DNA macrorestriction profile as the human- and food-derived strains isolated during the first outbreak. Analysis of the distribution and supply chains of the cases’ points of purchase identified a wholesaler-affineur “B,” common to all the cases’ points of purchase. The cheeses sold by wholesaler “B” came from producers other than producer “A,” who was responsible for the first outbreak. However, at the time of the second outbreak, this wholesaler still had cheese in stock in its cellars—seized during the first outbreak and awaiting destruction. The results of the investigations indicate that these two outbreaks were linked to the consumption of raw-milk Cantal. The first outbreak was linked to persistent contamination with Salmonella Enteritidis at a Cantal production facility. Contamination with the outbreak strain at another Cantal production facility or cross-contamination in the ripener’s cellar are the two hypotheses put forward regarding the second outbreak. (R.A.)