- The question whether there is a transmissible pathogenetic agent as a cause for Crohn's disease, remains unanswered. Measles virus has been the subject of many intensive studies, in the attempt to find a role for it in the pathogenesis of inflammatory bowel disease. Whether an early infection with measles virus may predispose to Crohn's disease in later life is still not clear. We conducted a large scale multicentre study, in order to obtain sufficient data to answer this question. To do so, we compared inflammatory bowel disease patients, with Crohn's disease or ulcerative colitis, with two matched control groups: clinical controls, and community controls. A total of 531 patients, 271 with ulcerative colitis and 260 with Crohn's disease were interviewed, as well as 903 matched controls. Blood from 104 inflammatory bowel disease patients and 50 controls was tested for antibodies to measles virus. We did not find any differences related to measles vaccination, either in Crohn's disease or in ulcerative colitis. Exposure to measles in childhood was more frequent in Crohn's disease patients than in their controls, the difference being statistically significant (p < 0.05) in relation to community controls. The presence of IgG antibodies to measles virus was higher in patients with Crohn's disease than in patients with ulcerative colitis or controls (p = 0.084). Another observation of interest was the finding that Crohn's disease patients who had measles in childhood, more frequently had large bowel disease than those who had not had measles. These data lead us to postulate that there may be a role for measles infection in Crohn's disease, even if, at present, this role remains unclear.