The etiology of Crohn's disease, which is a chronic inflammatory condition that potentially involves any location of the alimentary tract from the mouth to the anus, is unknown. However, there is strong evidence that vascular damage could play a role in the pathogenesis of Crohn's disease. Crohn's disease is mediated by multifocal gastrointestinal infarctions, which occur at an early stage in the disease process. Persistent activation of coagulation in patients with Crohn's disease has been shown. In contrast, hemophilia is an inherited disorder of coagulation. The deficiencies of clotting factors usually involve occult or overt bleeding. The pathogenic mechanisms of Crohn's disease and hemophilia are incompatible. An association between Crohn's disease and hemophilia has not been reported in Korea. We managed 21- and 33-year-old men with Crohn's disease associated with hemophilia, who presented with hematochezia.