PURPOSE: Crohn's disease is an inflammatory bowel disease with various symptoms and progressions. For effective identification of various causes and follow up of patients, we used the Vienna Classification from 1998, but we started applying the Montreal Classification in 2005. In this study, our aim was to identify the clinical characteristics of Korean patients with Crohn's disease by using the Montreal Classification. METHODS: A retrospective study was carried out among 111 patients who were evaluated at KyungHee Medical Center from March 1986 through February 2008 as having Crohn's disease. RESULTS: The male-to-female ratio was 1.8:1, and the average age was 27.2+/-9.6 yr. Abdominal pain was the major symptom, and extraintestinal manifestations were seen in 16 cases. Of the Crohn's disease patients, 25.2% were initially misdiagnosed as having tuberculosis. Concerning age at diagnosis, A2 (patients 17 to 40 yr of age) was the largest group. The most common disease location was the ileocolon (L3), and a combined upper gastrointestinal lesion (L4) was most commonly seen in L3. The most common disease behaviors were nonstricturing and nonpenetrating (B1), and although perianal lesions were most common in B1, there were no statistical correlations (P=0.061). Surgical treatments were performed in 46 cases, especially in cases involving complex disease (stricturing&penetrating) (P<0.005) and ileal disease (L1) (P=0.024). CONCLUSION: According to the Montreal Classification of Korean Crohn's disease patients, a more stable manifestation was seen in the group with lower age at diagnosis. Perianal lesions did not have any correlation with the form in which the disease manifested itself. Complex disease and ileal disease required a surgical procedure the most.