Autologous 111In-oxine-labeled granulocytes have proved to be valuable for the localization of inflammatory bowel diseases, especially Crohn's disease and ulcerative colitis. Other rare inflammatory bowel diseases also yield positive 111In scans. One case of Yersinia infection of the terminal ileum (Yersinia enterocolitica) showing an accumulation of 111In-oxine-labeled granulocytes 0.5, 4, and 24 h after the reinjection of the labeled cells is described. The 4-day fecal excretion of 111In-oxine granulocytes showed a slight inflammatory activity of the terminal ileum. One negative scan is reported in a cotrimoxazole-treated patient with Yersinia infection.