Corticosteroids are effective in bringing about clinical remission for ulcerative colitis. However, relapsed cases are frequently refractory to corticosteroids. In addition, the long-term use of corticosteroids often causes serious side effects. We have already reported that leukocyte apheresis using a centrifugal procedure was effective for patients with corticosteroid-resistant ulcerative colitis after conducting a pilot study in 14 patients. In the present paper, the clinical efficacy of leukocyte apheresis using a centrifugal procedure was evaluated again for corticosteroid-resistant ulcerative colitis. Twenty-three patients with corticosteroid-resistant severely active ulcerative colitis were treated by centrifugal leukocyte apheresis. Eighteen patients (78.3%) achieved clinical remission which was evaluated by the clinical activity index within 4 weeks after apheresis. Both colonoscopic and histological examinations confirmed the beneficial effect of this procedure. No significant side effects were noticed throughout the therapy.