During knee arthroplasty, autologous blood donation is frequently used as an alternative to homologous blood transfusion. The hemoglobin level determines the organism answer to the anemia induced by the iteratives phlebotomies. We reviewed retrospectively 140 patients to correlate the hemoglobin levels before the predonations, pre- and postoperatively. In our series, the hemoglobin thresholds to evaluate the risks for an allo- or autotransfusion are consistent with previous findings. We set up a transfusional program for the patient undergoing knee arthroplasty.