A19-year-old man complaining of severe diarrhea and hematochezia was admitted to our hospital. Endoscopic findings and laboratory data revealed that he had ulcerative colitis (UC). Despite combination therapy with high-dose corticosteroids and intensive granulocytapheresis, his condition did not improve. Therefore, we initiated tacrolimus therapy. Intravenous administration of tacrolimus with a trough level of 10 to 15 ng/ml relieved his abdominal symptoms within 1 week. The patient experienced no UC relapse 1 year after treatment with oral tacrolimus. Tacrolimus is a promising therapy for patients with UC refractory to the combination of high-dose corticosteroids and leukocytapheresis.