Cholangiocellular carcinoma developed in two uremic patients with polycystic kidney and liver disease, who had been treated with intermittent hemodialysis for one and nine years. In one case, in situ transformation of the liver cyst epithelium into cholangiocellular carcinoma could be demonstrated. The incidence of cholangiocellular carcinoma in patients undergoing long-term dialysis for polycystic kidney and liver disease, however, has yet to be determined.