The aim of the work was to create a well defined and sufficiently large of children affected by inflammatory bowel disease (IBD), treated in Centers for Children Gastroenterology in the Czech Republic (CZ) in the years 1990-2001 and to determine incidence of Crohn disease in children younger than 15 years in CZ. Methods: Diagnostic criteria for Crohn disease (CN), idiopathic proctocolitis (IPC) and indeterminate colitis (IC) were defined. Medical documentation provided the source of basic information about the children, where the diagnostic criteria were fulfilled and a standardized protocol was filled out. The protocols were controlled to find out, whether the data correspond to defined criteria and processed further. The study was of retrospective character during the years 1990-1999 and prospective in the years 2000 and 2001. Results: Seven hundred and forty four protocols were obtained and further processed from 25 workplaces dealing with diagnostics and therapy of IBD in children: 82 (11%) were excluded, since data in the protocols were incomplete (43) or diagnosis of CN was not certain (39). The diagnosis of CN was established in 223 (47.5%), IPC in 200 (42.6%) and IC in 46 (9.8%) patients. The age median at the time of diagnosis was 14 years in CN and IPC, respectively, and 13 years in IC. In 12 patients (3%) therewas a change in diagnosis during the period of observation (9 times from IC to CN or IPC, three times from IPC to CN). The incidence of CN in children up to 15 years of age was 0.30/100,000 in the period of 1990-1992, 0.28 in 1993-1998, and 1.06 in 1997-2000 (P<0.001). The results obtained by processing 193 protocols sent out as soon as the patient with IBD reached 18 years of age will be published separately. Conclusion: The information about 662 children and adolescents with IBD obtained during our investigation is not different from data in literature. Incidence of CN in childern up to 15 years of age proved to be 1.06/100,000 in the years 1996-2000.

        Key words: inflammatory bowel disease, Crohn disease, proctocolitis idiopathica, indeterminate colitis, incidence