Prirnary sclerosing cholangitis, a chronic progressive cholestatic hepatobiliary disorder of unknown etiology, is characterized by inflammation, scarring and obliteration of bile duct leading to biliary cirrhosis and liver failure. Because histologic finding has only a limited role in the diagnosis, the gold standard for establishing the diagnosis is cholangiographic demonstration of typical diffuse biliary stricutre or beading. The natural history is extremely variable. We report two cases of primary sclerosing cholangitis diagnosed by repeated endoscopic retrograde cholangiographies. They were followed up for 7 and 2 years, respectively. (Kor J Gastrointest Endosc 15: 788-794, 1995)