SUMMARYBackground: Functional gastrointestinal disorders cause substantial morbidity, but not mortality. Alosetron may achieve 'adequate relief ' in diarrhoea-predominant irritable bowel syndrome, but may cause major complications, including death. Aim: To appraise, quantitatively, the trade-off between possible symptomatic improvement and serious complications in the treatment of functional gastrointestinal disorders. Methods: A decision analytical model was used to examine alosetron or standard treatment for 6 months in 45-year-old women with diarrhoea-predominant irritable bowel syndrome using the health care system's perspective. Results: Assuming a 14% higher 'adequate relief' rate with alosetron compared to standard care, and a