Symptomatic erythrocytosis developed in a 59-year-old man with polycystic kidney disease (PKD) while he was receiving maintenance hemodialysis. Major clinical and laboratory data suggested a diagnosis of polycythemia vera (PV), despite a normal serum alkaline phosphatase level and leukocyte count. Secondary erythrocytosis, related to chronic hypoxemia and increased erythropoietin production, was excluded by appropriate laboratory studies. Despite previous documentation of secondary erythrocytosis in patients receiving hemodialysis, to my knowledge, PV has not been described in this population.