Preoperative autologous blood donation (PABD) is a well established transfusion practice in elective orthopaedic surgery, involving immunologic and infective advantages but also involving exposure to not negligible risks, and costs as well. The aim of this study was to assess the real need for blood transfusions in primary total knee arthroplasty (TKA). Between January 2000 and July 2005, 214 patients underwent primary unilateral TKA. Altogether, 416 autologous blood units were collected, however only 47 (11.3%) were transfused. Thirty-eight patients (17.8%) received autologous blood, while 4 of them (10.5%) also received allogeneic blood. Based on the results of this study, PABD should be recommended in well selected patients undergoing TKA: older female patients with a low basal haemoglobin level.