The clinical and radiological findings in four patients with primary sclerosing cholangitis one of whom had coexistent cholangiocarcinoma, are reported. The need for surgical exploration to make the diagnosis was averted by the use of endoscopic retrograde cholangiography in one patient who was managed initially with medical treatment alone. Endoscopic cholangiography may be used to monitor the progress of the sclerosing lesions; but failure to fill the intrahepatic ducts is associated with a poor prognosis due either to the severity of the sclerosing process or the presence of coexistent cholangiocarcinoma.