OBJECTIVE: Estimate the burden of IBS comparing resource use between IBS-patients (IBSp) and non-IBS subjects(controls) during a 1-year follow up. METHODS: Observational, prospective study including 517 IBSp, meeting Rome II criteria, and 84 controls. Controls were selected from those subjects who had attended a health centre due to digestive problems (excluding IBS). Both samples were selected from the consulting offices of 92 Spanish gastroenterologists and Primary Care Physicians. IBSp and controls attended a total of 5 visits at 3 month intervals. During first month after each visit patients recorded drug utilization and indirect resource in a diarycard. Direct resource was collected by investigators in follow-up medical controls. RESULTS: Mean patients age (SD) was 43 (14) years and 75% were female. No differences in age and gender were observed between IBSp and controls. 90% of IBSp and 100% of controls visited a clinic at least once (p<0.01), but only IBSp (52%) did it due to abdominal pain. Hospitalizations were registered in 7.5% of IBSp and 2.9% of controls. Thirty-eight percent of IBSp and 15 % of control were assisted in an emergency guard at least once (p <0.01); abdominal pain was the main reason for IBSp to attend the emergency guard (11%). 43% of IBSp required some specific test due to their abdominal pathology (blood samples, gastroscopy or colonoscopy). Mean patient cost associated with resources used was much higher in IBSp (€413.39) than in controls (€143.94)(p <0.01). In terms of indirect resources, 59% of IBSp and 26 % of controls experienced limited or reduced performance at work (p <0.01). Mean patient cost associated with absence from work at one year was also much higher for IBSp (€502.21€) than for controls (€109.70)(p <0.01). CONCLUSIONS: This prospective 1-year follow-up study confirms that IBS is associated with an important burden in terms of direct and indirect costs and that IBSp use more health resources and experience higher productivity loss compared with non-IBS.