Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders, with an estimated prevalence rate in the general population of 10-15% in industrialised countries. Although IBS is not a life-threatening disease, it contributes significantly to a large segment of healthcare resource consumption. This review provides an overview of studies addressing the direct and indirect costs of IBS in the US and the UK. A systematic literature search was conducted in MEDLINE and the Cochrane library; additionally, all reference lists covering the years from 1960 to May 2004 were scanned. Twenty-four publications for the US and the UK, published between 1991 and 2003, were identified: 6 were excluded, 18 were included. Data for the UK, US and UK + US were reported in 5, 11 and 2 publications, respectively. Total direct cost estimates per patient per year ranged from US 348 dollars to US 8750 dollars (calculated for year 2002). The average number of days off work per year because of IBS was between 8.5 and 21.6; indirect costs ranged from US 355 dollars to US 3344 dollars. The total costs and cost components of IBS are influenced by several factors: features of the investigated patient group (age, limitation to healthcare seekers or all IBS patients, comorbidity, severity of symptoms), database used, method of data collection (retrospective or prospective, varying cost components, time-point of data collection in relation to index-date of IBS diagnosis, method of cost calculation [incidence or prevalence based]) and different healthcare systems in the US and the UK. These factors led to the incomparability of published data, thus no comprehensive picture can be drawn of the total costs related to IBS in the UK and US. Data underline the magnitude of the economic impact of IBS in the UK and US, which is increased by a factor of 1.1-6.0, compared with matched non-IBS control groups. IBS contributes both direct and indirect costs to the total healthcare bill. Further studies should take influencial factors into account and report related data carefully in order to provide useful and comparable published cost data. Additionally, further research on the cost effectiveness of diagnostic procedures and therapies in IBS is required to define strategies to help IBS patients improve their quality of life and reduce related costs.