Primary sclerosing cholangitis (PSC) is an autoimmune disease of the hepatobiliary system for which effective therapy has not been established. Leukocytapheresis (LCAP) therapy is known to effective in patients with ulcerative colitis (UC). In addition, effects of LCAP therapy were reported on some autoimmune diseases such as Crohn's disease, rheumatoid arthritis and rapidly progressive glomerulonephritis. Here we report the case of a 29-year-old man with PSC associated with UC who was treated with LCAP therapy. He had a 16-year history of UC and a 12-year history of PSC. Although he was under treatment with prednisolone and ursodeoxycholic acid, exacerbation of UC and PSC-associated cholestasis were seen. Since he showed side effects of prednisolone, he was treated with LCAP. Not only improvement of UC, but also decreased serum alkaline phosphatase, gamma-guanosine triphosphate and total bile acids, suggesting improvement of PSC-associated cholestaisis, were seen after treatment with LCAP. Our experience with this case suggests that LCAP therapy could be a new effective therapeutic strategy for patients with PSC associated with UC.