Crohn's disease belongs to the inflammatory bowel diseases. Inflammatory changes can be located in any part of the gastrointestinal tract including rarely oral cavity. We present a case of a 21 years old woman with unhealed by the local treatment, and verified by histological examination, inflammatory changes of oral cavity. These changes had proceed the diagnosis of typical changes in gastrointestinal tract for 6 months. Changes were located in terminal ileum and colon and were confirmed by colonoscopic, histologic and radiologic studies. Standard therapy of Crohn's disease with antiinflammatory and immunosuppressive drugs led to the healing of oral changes. We point out on the necessity of proper differential diagnosis of problematic unhealing changes, particularly with ulcerations of oral mucosa in young patients. Dental examination with histological confirmation of mucosal changes may be helpful in proper diagnosis of Crohn's disease in the young group of patients.