A 2-year-old child with a febrile, non-bloody diarrheal illness of acute onset with repeatedly negative stool and blood cultures for pathogenic bacteria is presented. Sigmoidoscopic and roentgenographic studies revealed an inflammatory colitis. Unfortunately, diagnostic perserverance and a high index of suspicion resulted in a positive stool culture for Yersinia enterocolitica. Serologic study and clinical course provided data consistent with the diagnosis of an infectious colitis due to Yersinia enterocolitica. This case demonstrates the necessity to consider Yersinia enterocolitica in the radiographic differential diagnosis of Crohn's disease of the colon or ulcerative colitis, as well as intractable diarrhea of childhood.