Résumé : To determine the risk factors for Yersinia enterocolitica (YE) infection in Belgium, which is the country with the highest incidence of this infection, 40 persons with YE infections due to serotype O:3 (n = 36) or O:9 (n = 4) were compared with matched controls. Most patients had acute gastroenteritis; 1 had a liver abscess. 20% were admitted to hospital; the mean duration of hospital stay was 9 days. YE infection was strongly associated with eating raw pork in the weeks before onset (odds ratio = 12, p = 0.00002), a factor that accounted for 58% of the YE infections studied. 14 (18%) of 79 families surveyed at a well-baby clinic fed their children raw pork from a median age of 18 months. Specific control measures to reduce contamination and consumption of raw pork may reduce the incidence of YE infections.