In the past four years three excellent and comprehensive books on inflammatory bowel disease have been published.*RF 1-3* In a total of 1812 pages 156 contributors provide detailed accounts of the recent striking rise in the incidence of Crohn's disease but not ulcerative colitis in most developed countries; patients' genetic disposition (the dis-eases are apparently not HLA related); and clinical features, immunology, pathology, complications, and management options. Can there be much left to find out? Regrettably for the 120 000 or so patients with inflammatory bowel disease in Britain, from toddlers to octogenarians, the answer is yes. And despite inflam-matory bowel disease being unfashionable and attracting little research funding, there is a wealth of research going on.

Theories of the cause of inflammatory bowel disease abound. Current front runners include a range of types of immune dysregulation, such as abnormally vigorous stimulation of the gut immune system by products of the commensal flora, inappropriate activation of a single component among the many gut immune cells and mediators, or failure of an inhibitory signal that normally switches off a protective local inflammatory reaction. …