Previous studies have identified a link between anger and somatization. However, little is known about the associations between anger and the development and progression of Functional Gastrointestinal Disorders (FGID). The study aim was to determine the associations between FGID and anger, anxiety, and depression. Participants in this cross-sectional observational study were 109 consecutive patients aged 18-64 years with FGID at Gastroenterology Clinic of Baskent University Hospital. A control group comprised of 96 individuals with no chronic gastrointestinal disorders recruited via snowball sampling. Sociodemographic and clinical information were obtained and participants completed the Hospital Anxiety and Depression Scale and the State-Trait Anger Expression Inventory-2. FGID participants scored higher than controls on depression, anxiety, state anger, and anger expression-in. When the FGID group was divided into upper and lower gastrointestinal symptom groups, the lower symptom group showed higher anger expression-out scores than the upper symptom group. Anger may contribute to the etiology and development of FGID. This is the first study to demonstrate a significant psychological difference between individuals with lower and upper FGID. Interdisciplinary collaboration with gastroenterologists and psychiatrists could strengthen FGID evaluation and may improve treatment compliance.