The irritable bowel syndrome accounts for 30 to 50 per cent of patients cared for by gastroenterology practices. Irritable bowel syndrome is more common than inflammatory bowel disease. Therefore, it should not be surprising that some patients with inflammatory bowel disease are initially told that they have irritable bowel syndrome before a diagnosis of inflammatory bowel disease is firmly established. This article contends that many people have both irritable bowel syndrome and inflammatory bowel disease.