Introduction - On November 15, 2010, three confirmed cases of toxoplasmosis were reported to the Midi-Pyrénées Regional Health Agency. The patients were members of the same family and had shared a single meal on October 3, 2010, raising suspicion of a foodborne illness outbreak. Since clusters of toxoplasmosis cases are rare, investigations were conducted to document the outbreak. Methods - A description of the initial cases and an active search were conducted in a 20-km study area around the butcher shop in Aveyron where the suspected food was purchased, based on a case definition of active toxoplasmosis occurring between October 1, 2010, and December 14, 2010. Epidemiological data were collected and linked to clinical and serological follow-up. A sample of the suspected food item allowed for genotyping of the isolate likely responsible for the infection. A traceability investigation was conducted into the origin and distribution of the food item potentially responsible for the contamination. Results - No additional cases were identified in the study area. Five of the seven individuals exposed to the meal had recent active toxoplasmosis (incidence rate: 71%; sex ratio: 0.67; mean age: 21 years). None presented with severe symptoms, and no complications arose. Testing for the parasite in the remains of the undercooked leg of lamb revealed the presence of significant amounts of Toxoplasma genotype II DNA. The traceability investigation did not identify the farm of origin of the consumed lamb. Conclusion - Our investigations have described a small-scale Toxoplasma foodborne illness outbreak and determined the source of contamination. However, it is possible that other cases went undetected, as the infection is most often asymptomatic. Foodborne toxoplasmosis outbreaks are poorly documented, and information regarding the risk of contamination from undercooked lamb should be more widely disseminated. (R.A.)