Irritable bowel syndrome is extremely common and its severity is widely underestimated. Unfortunately, the current pharmacological treatment of this condition is far from satisfactory which might suggest that it would be an area in which the pharmaceutical industry would take a great interest. However, drug development in this field, especially in relation to 5-hydroxytryptamine (5-HT), has been beset by difficulties with side effects and, what some authorities would claim, an unnecessarily strict regulatory climate based on the perception that irritable bowel syndrome is not a particularly serious condition. This has resulted in a rapid withdrawal from the scene by a number of companies although with the identification of some potential new therapeutic targets, the area has not been totally abandoned. © 2009 Informa UK Ltd.