Left ventricular hypertrophy is an independent determinant of survival in patients with end-stage renal disease, and anemia is one determinant of hypertrophy in such patients. Accordingly, the authors studied 22 dialysis patients by echocardiography before and after correction of their anemia with recombinant human erythropoietin. Observers were blinded to patient identity and order of studies. Hemoglobin increased from 63 +/- 8 g/L (mean +/- standard deviation) to 114 +/- 15 g/L; an increase of at least 30 g/L over baseline was maintained for eight months in all patients. Left ventricular mass decreased from 253 +/- 77 to 215 +/- 71 g (2P = 0.0004) and left ventricular end diastolic volume fell from 173 +/- 60 mL to 138 +/- 48 mL (P less than 0.0001). The reduction in mass and decrease in end diastolic volume, however, were seen only in those with significant hypertrophy at the onset of therapy. The authors conclude that partial regression of left ventricular hypertrophy is possible within a short time period through correction of anemia in dialysis patients. Whether this will improve survival in end-stage renal disease remains to be determined.