The prevalence of irritable bowel syndrome (IBS) is high wherever it is assessed. The definition is still controversial, but the IBS patient's characteristics are quite similar in industrialized countries. The lack of a definite biological marker results in the prescription of many complementary examinations. The diagnosis of IBS remains an elimination diagnosis, despite the publication of the Rome criteria, which has attempted to advance toward a positive diagnosis. Abdominal pain or discomfort are the main symptoms and are the major reasons for consulting. The quality of life is impaired in IBS and is clearly correlated with symptom severity. All these points at least partially explain the economic burden of IBS on health care resources. The cost of IBS is difficult to assess because of its different components: the direct costs such as the number of medical consultations, drug consumption, and the number and quality of complementary investigations are easier to evaluate than the indirect costs such as work absenteeism or altered presenteeism, which can have a major impact on the cost of IBS.