The aim of this study was to elucidate the mechanism of anemia associated with autonomic dysfunction in rats. Using 6-hydroxydopamine (6-OHDA)-treated sympathectomized rats, changes in systolic blood pressure, plasma catecholamine levels, hemograms, erythropoietin (EPO) secretion, and beta-adrenergic receptors on erythrocytes were monitored, and compared with desipramine- and 6-OHDA-treated, and control rats. In 6-OHDA-treated rats, systolic blood pressure and plasma catecholamine levels significantly decreased from 7 days after 6-OHDA administration, returning to the control values on day 28. Hemoglobin (Hb), hematocrit (Hct) and red blood cell (RBC) levels significantly decreased from day 14 to day 28, and reached normal values after day 35, but neither corpuscular constants nor white blood cell (WBC) levels changed after anemia occurred. Administration of desipramine 1 day before 6-OHDA injection prevented anemia. EPO levels did not elevate, even after bloodletting to load anemia, and the EPO circadian rhythm was irregular in 6-OHDA-treated rats. beta-adrenergic receptors measured using 125I-cyanopindolol (CYP) significantly decreased from day 7 to day 28, and reached normal values after day 35. These results suggest that irregular EPO secretion via disordered autonomic nerves may induce anemia in patients with autonomic disorders.