Objective: In this prospective, randomized, controlled trial we sought to evaluate the effectiveness of acute normovolemic hemodilution (ANH) in terms of decreasing the need for allogeneic transfusion after conventional unilateral total knee arthroplasty (TKA). Summary of Background Data: TKA is often performed with an occlusive tourniquet, and thus, it could be considered ideally suited for ANH, because the chief benefit of ANH is red blood cell loss reduction and the shedding of whole blood perioperatively at lower hematocrit levels. Methods: Between January 2012 and May 2012, 40 consecutive patients scheduled to undergo elective, primary, cemented, unilateral TKA for knee osteoarthritis were enrolled. Patients were randomized to either a study (ANH) group (n=20) (Group A) or a control group (n=20) (Group B). Unit of allogeneic blood transfused was considered the primary outcomes. Results : In the ANH group, less allogeneic blood transfusion (6 units in Group A vs 15 units in Group B) was required after operation. Six patients, who required a transfusion in Group A received 1 unit of allogeneic blood. In contrast, 6 of 9 patients, who required transfusion in Group B, received at least 2 units of allogeneic blood (p<0.05). There was no complication related to the methods of the protocol. Conclusions: ANH is likely to reduce postoperative allogeneic transfusion requirement in patients undergoing unilateral TKA. However, adjunctive strategies are required to further reduce allogeneic blood transfusion requirements.