Three weeks after the 5/6 nephrectomy, the CRF rats developed anemia, as shown by the reduced Hb concentration, RBC count and HTC (p < 0.001 for all), when compared to Sham group; RET count presented also a decrease (p < 0.05); this anemia persisted until the end of the protocol. This evidence concerns the gene GSTM1 and anemia (phenotype).