Autologous blood donation is designed to avoid complications from allogeneic blood, leaving units of blood in the general blood supply. It is unclear how efficient these programmes are in accomplishing these goals. It is unclear if autologous donation provokes increased need for any transfusion following surgery and whether it can be avoided in low-risk surgeries. Of 430 patients undergoing unilateral primary knee replacement arthroplasty over 12 months in our hospital, 309 had autologous donations and 121 did not. Of the 121 patients who did not donate, 36% completed surgery without transfusion, whereas only 17% of those who had autologous donations did so (P < 0.05). Age less than 65 years, higher baseline and postoperative haemoglobin levels were associated with lower transfusion rates. Patients who had autologous donations were approximately four times more likely to be transfused. As the number of autologous units donated increased, transfusions following surgery increased. Autologous donation did reduce allogeneic blood transfusions. Therefore, autologous blood donation for unilateral total knee arthroplasty is associated with overall increased transfusion rates, but with reduced need for allogeneic blood, independent of other clinical factors associated with transfusion. Therefore, there is need for reconsideration of these programmes relative to specific surgeries.