A case of primary sclerosing cholangitis (PSC) successfully treated with cyclosporine is described. A 65-year-old man who presented with jaundice and anemia was diagnosed as having PSC, accompanied by pancreatic duct abnormalities. Cholangiography and pancreatography showed marked improvements following combined therapy with cyclosporine and methylprednisolone. Cyclosporine seems to be a promising drug for the treatment of patients with PSC. This report reasons that the same disease process affects both the pancreatic ducts and the bile ducts, and that stagnation of pancreatic juice may have a role to play in the pancreatic duct abnormalities.