Anemia, a major component of the uremia syndrome before the introduction of recombinant human erythropoietin (EPO), was treated primarily with blood transfusions in patients with end-stage renal disease (ESRD). After multi-center trials of EPO in hemodialysis patients showed that blood transfusion requirements fell by > or = 50% in hemodialysis facilities using EPO, it was anticipated that blood transfusion therapy in hemodialysis patients would be eliminated in patients treated with EPO. The authors examined the annual rate of blood transfusions from 1983 to 1992 in hemodialysis patients admitted to an inner city municipal hospital. Hospital computer records were accessed to obtain a list of all patients admitted to the hospital who received a blood transfusion between 1983 and 1992. From these data, lists of transfused hemodialysis patients were generated. The authors compared the mean annual blood transfusion rate per hospital patient in the pre EPO era (1983-1985) with the same rate during the time of EPO trial (1986-1988) and during the time of wide clinical availability of EPO (1989-1992). In addition, the authors examined individual hospital medical records of hemodialysis patients who received transfusions in 1986 and 1992. The mean annual blood transfusion rate was 38% (range, 36-39%) in the pre EPO era, 19% (range, 16-24%) during the years of the EPO trial, and 23% (range, 21-24%) after EPO was widely used in 1989, comparing the latest rate with either of the two earlier times (p < 0.0001). Of all of the years tabulated, the blood transfusion rate was lowest in 1987, the second year of the EPO clinical trial, with only 94 (16%) of 592 hemodialyzed patients given a blood transfusion. The rate of blood transfusions remained low in 1988 (18%) but subsequently has increased. Using 1987 as a reference point, the rate of blood transfusion in hemodialysis patients increased in each of the subsequent years after 1988 (18%, p < 0.33); 1989 (23%, p < 0.001), 1990 (24%, p < 0.0001), 1991 (21%, p < 0.02), and 1992 (23%, p < 0.0001). The authors conclude that, despite the availability and broad use of EPO in uremia therapy since 1989, a significant proportion of hemodialysis patients receiving EPO treatment require blood transfusions for anemia.