On November 15, 2010, three confirmed cases of toxoplasmosis in members of the same family were reported to the Midi-Pyrénées Regional Health Agency. The only meal they shared, on October 3, 2010—which included undercooked lamb—led to suspicion of a foodborne illness outbreak. Since clusters of toxoplasmosis cases are rare, investigations were conducted to document the outbreak. Epidemiological, clinical, and serological data were collected from those who attended the shared meal. Genotyping of the strain isolated from the suspected food source was performed, along with a traceability investigation. Of the 7 people exposed to the meal, the 5 susceptible individuals presented with recent, uncomplicated active toxoplasmosis (attack rate 100%; mean age 21 years). Genotypic analysis of the DNA from the frozen half of the leg of lamb revealed genotype II. The farm of origin of the lamb could not be identified. Our investigation allowed us to describe a small-scale Toxoplasma foodborne illness outbreak and determine the source of contamination. However, it is possible that other cases went unreported, as the infection is most often asymptomatic. Foodborne Toxoplasma infections are poorly documented, and information regarding the risk of contamination from undercooked lamb should be more widely disseminated. (R.A.)