A 53-year-old man had steroid-dependent ulcerative colitis. Leukocytapheresis (LCAP) was carried out to induce remission, but soon hematuria and renal dysfunction appeared. Since he had no autoimmune hemolytic anemia, and there was no possibility of his having had hemolytic uremic syndrome, it was considered that this hemolysis could have been caused by mechanical stimulation on the LCAP column, and then the hemolysate flowed into his body. We should be aware that hematuria might occur as a side effect of LCAP.