【Abstract】 Objective To investigate the correlation of serum immunoreactive parathyroid hormone (iPTH) with anemia and hypo-responsiveness to erythropoietin (EPO) in maintenance hemodialysis patients. Methods We studied 46 maintenance hemodialysis patients (28 males and 18 females, aged 61.00 +15.59 years). Blood samples were collected at the day on hemodialysis for the determination of serum hemoglobin (Hb), hematocrit (Hct), albumin, ferritin, Ca, P, creatinine and iPTH. Higher ratio of recombinant human erythropoietin (r-HuEPO) dosage to Hct (EPO/Hct) was defined as hypo-responsiveness to EPO. Results Patients with elevated serum iPTH (20 cases, 43.5%) showed higher EPO/Hct ratio, serum P and Ca x P product, but lower Hb and Hct, as compared with those of the patients with normal serum iPTH (26 cases, 56.5%). Multiple stepwise regression analysis found that serum iPTH level, patient’s age and hemodialysis duration were the best predictors for EPO/Hct ratio (R2=0.388, P=0.039). Conclusions Secondary hyperparathyroidism is one of the complications in maintenance hemodialysis patients. Oversecretion of PTH is the most important factor causing hypo-responsiveness to EPO.