In the present study, the relationship between the blood erythropoietin level and cardiac function was investigated in 15 patients on chronic hemodialysis who developed chronic heart failure. Another 45 patients without cardiac dysfunction were selected as a control group that was matched for gender, age, and the duration of dialysis. The erythropoietin level was 256.3 +/- 481.8 mU/ml in the heart failure group, which was significantly higher than that in the control group (17.0 +/- 10.0 mU/ml, P < 0.01). Eight of the 15 patients in the heart failure group maintained a hematocrit of more than 30% without receiving recombinant human erythropoietin therapy, whereas 29 of the 45 patients in the control group required erythropoietin. In the heart failure group, the erythropoietin level was significantly correlated with the levels of atrial natriuretic peptide and brain natriuretic peptide (P < 0.01). These results suggest that heart failure can increase the erythropoietin level in proportion to the severity of cardiac dysfunction, even in patients on long-term dialysis.