OBJECTIVES: Patient-reported outcomes are necessary to evaluate the gastrointestinal symptom profile of patients with functional constipation. Study objectives were to compare the gastrointestinal symptom profile of pediatric patients with functional constipation with matched healthy controls with the Pediatric Quality of Life Inventory Gastrointestinal Symptoms and Gastrointestinal Worry Scales and to establish clinical interpretability in functional constipation through identification of minimal important difference (MID) scores. The secondary objective compared the symptom profile of patients with functional constipation with patients with irritable bowel syndrome (IBS). METHODS: Gastrointestinal Symptoms and Worry Scales were completed in a 9-site study by 116 pediatric patients with functional constipation and 188 parents. 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 total of 341 families with healthy children and 43 families with patients with IBS completed the scales. RESULTS: A broad profile of gastrointestinal symptoms and worry were reported by patients with functional constipation in comparison with healthy controls (P<0.001) with large effect sizes (>0.80) across the majority of symptom domains. Patients with IBS manifested a broader symptom profile than functional constipation, with differences for stomach pain, stomach discomfort when eating, and worry about stomachaches, with similar constipation scores. CONCLUSIONS: Pediatric patients with functional constipation report a broad gastrointestinal symptom profile in comparison with healthy controls and only somewhat fewer symptoms than patients with IBS, highlighting the critical need for more efficacious interventions to achieve healthy functioning.