Leukocytapheresis (LCAP) using a leukocyte removal filter was performed for 8 patients with moderate to severe ulcerative colitis (UC). Significant clinical improvement was attained in 5 of 8 patients (62.5%). All of them had been suffering from moderately active colitis and received corticosteroid therapy. On the other hand, 3 patients with severely active disease and treated with little or no corticosteroid were resistant to LCAP. This result indicates that LCAP is an effective treatment for steroid-resistant cases of UC when combined with steroid therapy. LCAP alone, however, seems to have little efficacy for severely active UC.