We sought to prospectively characterize and compare the symptoms of children > or = 5 years of age with recurrent abdominal pain to previously established criteria for irritable bowel syndrome (IBS) in adults. For all eligible subjects, a detailed questionnaire concerning characteristics of abdominal pain and defecatory pattern was completed at presentation. In addition, a battery of screening tests was performed and additional evaluation was done at the discretion of their physician. In all, 227 subjects fulfilled the entrance criteria, but 56 were subsequently excluded because of diagnoses of inflammatory bowel disease (nine cases), lactose malabsorption (46 cases), or celiac disease (one case). Of the remaining 171 patients, 117 had IBS symptoms. In the IBS subjects, lower abdominal discomfort (p < 0.001), cramping pain (p < 0.0009), and increased flatus (p < 0.0003) were more common, whereas dyspeptic symptoms such as epigastric discomfort (p < 0.003), pain radiating to the chest (p < 0.009), and regurgitation (p < 0.02) were more common in the non-IBS subjects. Our study not only confirms the clinical heterogeneity of children with recurrent abdominal pain but also concomitantly demonstrates that most children with this disorder have symptoms that fulfill the standardized criteria for IBS in adults. The identification of subgroups of children with recurrent abdominal pain can provide a framework for the diagnosis of functional bowel disease as well as establish the need for invasive and expensive tests.