The optimal target hematocrit (Ht) level in recombinant human erythropoietin (rHuEPO) therapy remains controversial and has hardly been investigated in predialysis patients. We prospectively studied the regression of left ventricular hypertrophy (LVH) on echocardiography in nine predialysis patients with chronic renal failure after a partial correction (target Ht, 30%) and normalization (target Ht, 40%) of the Ht with rHuEPO treatment. Twenty-four-hour ambulatory blood pressure monitoring was also performed. The administration of rHuEPO significantly increased Ht to the target values. The rate of renal failure progression did not change during rHuEPO treatment for 12 months (Cr, from 6.2 ± 2.0 to 5.5 ± 2.1 mg/dL). The left ventricular mass index (LVMI) tended to decrease after a partial correction of anemia (Ht, 32.1% ± 1.8%) at 4 months, whereas it tended to significantly decrease after normalization of Ht (Ht, 39.1% ± 2.4%) at 12 months (baseline, 140.6 ± 12.1 g/m²; partial correction, 126.9 ± 10.0 g/m²; normalization, 111.2 ± 8.3 g/m²). All patients had received antihypertensive medication before rHuEPO administration, and additional drugs were also required in four cases during the study. As a result, a good overall blood pressure control was obtained without any adverse effects on the circadian blood pressure rhythm. In conclusion, from the perspective of LVH regression, the normalization of Ht was found to be more effective than that associated with a partial correction of anemia during rHuEPO therapy.