BACKGROUND AND AIM: Pain-predominant-functional gastrointestinal disorders (PP-FGIDs) are common. The diagnosis is clinical and there are no biological markers to characterize these conditions. Despite limited evidence, investigations are commonly performed. The aim of the study was to investigate diagnostic practices, yield, and costs in children with PP-FGIDs. PATIENTS AND METHODS: Charts of all of the children older than 4 years diagnosed as having abdominal pain were reviewed. Results and costs of diagnostic investigations were analyzed. RESULTS: Of 243 children with abdominal pain, 122 (50.2%) had PP-FGIDs (79 girls, mean age 12.7 years). All of the children underwent diagnostic work-up. Complete blood cell count was done in 91.8% of patients. None had elevated white blood cells, platelets, and low albumin. Six had either elevated erythrocyte sedimentation rate or C-reactive protein, but none had elevation of both; 4 of these 6 cases underwent endoscopies with normal results in 3 cases; Helicobacter pylori was found in 1 case. One child had elevated tissue transglutaminase 1 only antibodies with normal endoscopy. Amylase, lipase, direct bilirubin, stool cultures, and ova or parasites were always normal. One child had intermittent elevation of aspartate aminotransferase and alanine transaminase. There were no significant abnormalities in urinalysis or electrolytes. Abdominal x-rays were done in 38.5%, showing only retained stools in 13% of these patients. Abdominal ultrasound and computed tomography scan were done in 23.7% and 9% of cases, respectively, but were of no clinical value; 33.6% patients had esophagogastroduodenoscopy (9.7% abnormal: Helicobacter pylori, chemical gastritis, esophagitis) and 17.2% had colonoscopy (9.5% abnormal: rare fork crypts, lymphoid hyperplasia). Total costs: $744,726. Average cost per patient: $6104.30. CONCLUSIONS: In children with PP-FGIDs, investigations are common, costs are substantial, and yield is minimal.