OBJECTIVE The aim of this study was to determine the prevalence of gastrointestinal symptoms in patients with end-stage renal disease undergoing hemodialysis (HD) or peritoneal dialysis (PD) treatment. METHODS Patients undergoing HD or chronic ambulatory PD in the Department of Renal Medicine of our hospital were asked to complete a locally validated Rome II questionnaire. The same questionnaire was also administered to age- and gender-matched medical outpatients without renal failure, and community subjects. Patients on HD and their outpatient controls also completed the Hospital Anxiety and Depression Scale. RESULTS A total of 148 patients with end-stage renal disease (HD 100, PD 48) completed the study. Their results were compared with those of 148 age- and gender-matched medical outpatients without renal failure and 148 randomly selected community controls. Patients on dialysis treatment were more likely to have abdominal pain, use laxatives, and report symptoms consistent with functional vomiting and irritable bowel syndrome (IBS) (70%, 55%, 16%, and 25%) than age- and gender-matched medical outpatients without renal failure (21%, 11%, 1%, and 6%) and community controls (16%, 4%, 0%, and 8%). Among HD patients and their outpatient controls, the differences appeared to be unrelated to anxiety or depression. CONCLUSIONS Abdominal pain, laxative use, functional vomiting, and IBS were more common in uremic individuals than in controls without renal failure. Our data have not shown whether these differences are due to the uremic state itself, or, alternatively, its treatment.