Although up to 20% of patients with Crohn's disease have their first flare during childhood or adolescence, there are no or only a few randomized, controlled studies. However, big differences and uncertainty may be observed between the diagnosis and therapy of pediatricians and gastroenterologists specialized for adults. In addition, special problems result from the enormous somatic and psychological evolution during adolescence. The diagnosis is done as in adult patients by enteroclysm and ileocolonoscopy (including multiple biopsies) whereas a deep sedoanalgesia or anesthesia should be performed routinely. Corticosteroids are the gold standard for therapy of Crohn's disease in the adolescence (especially in cases with high inflammatory activity), but also enteral nutrition over 4-12 weeks--or a combination of both. A recent randomized controlled study demonstrates the positive effect of 6-mercaptopurine in newly diagnosed patients with Crohn's disease in the adolescence. 5-aminosalicylates or the probably more effective azathioprine/6-mercaptopurine could be used for prevention of recurrence in Crohn's disease. The therapy of ulcerative colitis is performed as in adults including the very effective local rectal applications. An accompanying psychosomatic therapy is recommended especially in young patients with disturbed separation from the parents and inadequate coping. The indication for surgery is similar to adults. However, a specific indication for earlier surgery is given, if severe malabsorption and delay of growth takes place in spite of adequate therapy, because this delay of growth could be only caught up before puberty. A conservative therapeutic regimen is recommended in young patients with perianal Crohn's disease.