OBJECTIVES: Patient-reported outcome (PRO) measures of gastrointestinal symptoms are recommended to determine treatment effects for irritable bowel syndrome (IBS) and functional abdominal pain (FAP). Study objectives were to compare the symptom profiles of pediatric patients with IBS or FAP with healthy controls and with each other using the PedsQL Gastrointestinal Symptoms and Gastrointestinal Worry Scales, and to establish clinical interpretability of PRO scale scores through identification of minimal important difference (MID) scores. METHODS: Gastrointestinal Symptoms and Worry Scales were completed in a 9-site study by 154 pediatric patients and 161 parents (162 families; IBS n = 46, FAP n = 119). Gastrointestinal Symptoms Scales measuring stomach pain, stomach discomfort when eating, food and drink limits, trouble swallowing, heartburn and reflux, nausea and vomiting, gas and bloating, constipation, blood in poop, and diarrhea were administered along with Gastrointestinal Worry Scales. A matched sample of 447 families with healthy children completed the scales. RESULTS: Gastrointestinal Symptoms and Worry Scales distinguished between patients with IBS or FAP compared with healthy controls (P < 0.001), with larger effect sizes (>1.50) for symptoms indicative of IBS or FAP, demonstrating a broad multidimensional gastrointestinal symptom profile and clinical interpretability with MID scores for individual PRO scales. Patients with IBS manifested more symptoms of constipation, gas and bloating, and diarrhea than patients with FAP. CONCLUSIONS: Patients with IBS or FAP manifested a broad gastrointestinal symptom profile compared with healthy controls with large differences, indicating the critical need for more effective interventions to bring patient functioning within the range of healthy functioning.