Current antifibrinolytics have decreased perioperative blood loss; however, some patients still require transfusions postoperatively. The authors sought to determine the risk factors associated with postoperative transfusions and to establish a "cutoff" preoperative hemoglobin threshold value specific to total knee arthroplasty (TKA) that would identify patients who would benefit from blood conservation programs. The institutional database was queried for primary TKA patients. Preoperative patient demographics and hemoglobin values were determined in addition to intraoperative and postoperative variables, including transfusion rate. Patients were stratified by whether they received a transfusion perioperatively, and risk factors were identified through univariable and multivariable analysis. Optimal cutoff values for hemoglobin were identified by concurrently maximizing the sensitivity and specificity for predicting the risk of a postoperative transfusion event. Men and women were analyzed independently. A total of 532 primary TKAs were included for analysis, and 33 patients (6.2%) required a transfusion. Advanced age (P=.019), low pre-operative hemoglobin value (P<.001), and failure to receive tranexamic acid (P<.001) were associated with increased risk of postoperative transfusion. A preoperative hemoglobin value of 12.5 g/dL was identified as the optimal cutoff for predicting postoperative transfusion requirements across all patients, with a sensitivity of 84.8% and a specificity of 76.4%. Preoperative anemia remains predictive of transfusion following TKA despite current antifibrinolytics. Patients with a preoperative hemoglobin value of less than 12.5 g/dL who are not receiving intravenous tranexamic acid are particularly at risk and should be considered for blood conservation programs. [Orthopedics. 2019; 42(2):103-109.].