Meckel's diverticulum is the most common congenital anomaly of the intestine. The association between Meckel's diverticulum and Crohn's disease is unclear. Meckel's diverticulum has previously been reported to be present in patients with Crohn's disease. However, the finding is typically incidental, and a bleeding Meckel's diverticulum in a patient with Crohn's disease is uncommon. Recently, we managed a 27-year-old man with known Crohn's disease who presented with hematochezia thought to be due to an ileal ulcer of Crohn's disease. At the time of intra-operative small bowel endoscopy, the hematochezia was shown to be due to bleeding from Meckel's diverticulum. Although the patient had already been diagnosed with Crohn's disease, we need to consider the possibility of other causes of bleeding.