The incidence of inflammatory bowel disease (IBD) in French children is not known. Therefore we conducted a prospective epidemiologic study of IBD in the region Nord-Pas-de-Calais (3.9 millions inhabitants). During the first 17 months of the study each new suspected case was reported by all (private and public) gastroenterologists in the region (n = 104) and a questionnaire was filled up at the gastroenterologist office by an epidemiologist. The final diagnosis of Crohn's disease (CD), ulcerative colitis (UC) or proctitis was made in a blind manner by two expert gastroenterologists. During the period under study, 47 new cases of IBD were registered in children (less than 17 years of age); 31 (66%) had CD, 7 (15%) had UC, and 9 (19%) had unclassified colitis. The incidence was 2.07/100,000 children/year for CD and 0.46/100,000 children/year for UC. These preliminary data suggest that the incidence of CD is high in Northern France.