Although the association between inflammatory bowel disease and gastrointestinal infections has been suggested, the mechanisms involved in the pathogenesis of Crohns disease (CD) are still undetermined. We report the case of a man, who presented with mesenteric adenitis initially due to a Yersinia pseudotubercolosis infection, who was later diagnosed with Crohns disease. This case is in keeping with recent evidence in the literature which suggests that CD is a disease linked to abnormal immune responses to enteric bacteria in genetically susceptible individuals.