A case of hemophagocytic syndrome associated with ulcerative colitis is very rare. A 32-year-old man visited the hospital complaining of fever and severe abdominal pain for 7 days. He was diagnosed to have ulcerative colitis 2 years ago and had been treated with sulfasalazine. Three months ago, he had abdominal pain, weight loss, and hematochezia, so prednisolone and mercaptopurine were added to the treatment. On admission, the physical examination showed splenomegaly. Peripheral blood counts revealed pancytopenia, and bone marrow aspirate smears showed many histiocytes with active hemophagocytosis. There was no evidence of viral and bacterial infections and other neoplasms, which were commonly associated with hemophagocytic syndrome. He was successfully treated with high dose steroid. We report this case along with a review of the related literatures.