Yersinia, Campylobacter, and Salmonella are pathological microorganisms which incidentally may specifically infect the ileocecal area (infectious ileocecitis). In such cases pain in the right lower quadrant is the predominant symptom, and diarrhea is absent or only mild. This symptomatology can lead to an unnecessary laparotomy for suspected appendicitis. At surgery a normal appendix is removed, while there is edematous thickening of ileum and cecum, and enlarged mesenteric lymph nodes. These ileocecal abnormalities give rise to a fairly characteristic US image, enabling the radiologist to rapidly differentiate infectious ileocecitis from appendicitis, thus preventing an unnecessary laparotomy. Infectious ileocecitis caused by Yersinia, Campylobacter, and Salmonella is a common mimicker of appendicitis, and its incidence at this moment is grossly underestimated. Ultrasound is presently the only means to prevent an unnecessary operation for this condition which is principally self-limiting and innocuous.