OBJECTIVE: The objective of this study was to report on the measurement properties of the Pediatric Quality of Life Inventory (PedsQL) Gastrointestinal Symptoms Module for patients with functional gastrointestinal (GI) disorders (FGIDs) and organic GI diseases, hereafter referred to as "GI disorders," for patient self-report ages between 5 and 18 and parent proxy-report for ages between 2 and 18 years. METHODS: The 74-item PedsQL GI Module and 23-item PedsQL Generic Core Scales were completed in a 9-site study by 584 patients and 682 parents. Patients had physician-diagnosed GI disorders (such as chronic constipation, functional abdominal pain, irritable bowel syndrome, functional dyspepsia, Crohn disease, ulcerative colitis, gastroesophageal reflux disease). RESULTS: Fourteen unidimensional scales were derived measuring stomach pain, stomach discomfort when eating, food and drink limits, trouble swallowing, heartburn and reflux, nausea and vomiting, gas and bloating, constipation, blood, diarrhea, worry, medicines, and communication. The PedsQL GI Module Scales evidenced excellent feasibility, excellent reliability for the Total Scale Scores (patient self-report alpha = 0.97, parent proxy-report alpha = 0.97), and good-to-excellent reliability for the 14 individual scales (patient self-report alpha = 0.67-0.94, parent proxy-report alpha = 0.77-0.95). Intercorrelations with the Generic Core Scales supported construct validity. Individual Symptoms Scales known-groups validity across 7 GI disorders was generally supported. Factor analysis supported the unidimensionality of the individual scales. CONCLUSIONS: The PedsQL GI Module Scales demonstrated acceptable-to-excellent measurement properties and may be used as common metrics to compare GI-specific symptoms in clinical research and practice both within and across patient groups for FGIDs and organic GI diseases.