The purpose of our study is to emphasize the central role of ultrasound (US) in finding the cause of abdominal pain in children. Ultrasound of the lower abdomen quadrant should be considered in all cases in which the clinical signs and symptoms are not diagnostic of appendicitis. There is a wide range of clinical syndromes and diseases which can easily be diagnosed using a high resolution ultrasound with adjunct of color and power Doppler. The spectrum of abnormalities includes appendicitis, mesenteric lymphadenitis, infectious ileocecitis, Crohn's disease, intussusception, ovarian cysts, and encysted cerebrospinal fluid. One of the most common causes of acute abdominal pain in children is acute terminal ileitis (infectious ileocecitis) with mesenteric lymphadenitis. Ultrasound is the best tool to rapidly differentiate this disease from acute appendicitis, and prevent unnecessary laparotomy (Ref. 12).