The aim of the present study was to assess whether there is an association between PTH and hemoglobin in CKD-patients without severely deranged serum PTH concentrations and who did not undergo previous therapy with erythropoietin stimulating agents and/or vitamin D. Confirmation of this association may have clinical relevance in assessing the cause of unexplained low hemoglobin level in CKD-patients. This evidence concerns the gene EPO and chronic kidney disease.