The treatment of CRF rats with a high dose of rHuEPO (200 IU/kg bw/week) rapidly corrected the anemia, and the Hb concentration reached significantly higher values until the ninth week, as compared to Sham and CRF rats; afterwards, the hematological measures declined to basal values, similar to those of the Sham group, due to formation of EPO-neutralizing antibodies. This evidence concerns the gene GSTM1 and anemia (phenotype).