Background Tranexamic acid (TXA) is often used to prevent excessive blood loss during bilateral TKA. Although it diminishes blood loss, TXA may have a potentially elevated thrombogenic risk with extra, unnecessary doses of TXA in this high-risk population. To date, the most efficacious dosing protocol in this setting has not yet been ascertained. Questions/purposes We compared one versus two doses of intravenous TXA in the setting of same-day bilateral TKA in terms of (1) perioperative blood loss that occurred during the hospital stay, (2) transfusion usage during the hospital stay, and (3) major complications occurring within 30 days of surgery.Methods Between August 2013 and October 2016, 309 patients underwent simultaneous bilateral TKA performed by one of five attending surgeons. During that time, indications for same-day bilateral TKA included bilateral knee pathology in which each knee was independently indicated for TKA and the patient preferred bilateral simultaneous TKAs versus staged bilateral surgeries. Patients who had cardiac disease or an American Society for Anesthesiologists physical classification score of greater than 2 were not generally indicated for bilateral simultaneous TKAs. After preoperative clearance from the primary physician and/or specialists as necessary, the decision for This study was funded by a grant from the Scripps Clinic Medical Group Foundation. One of the authors (WDB) certifies receipt of personal payments or benefits, during the study period (2013)(2014)(2015)(2016), in an amount of USD 10,000 to USD 100,000 from Zimmer Biomet; in an amount of USD 100,001 to USD 1,000,000 from DePuy; in an amount of USD 10,000 to USD 100,000 from Smith & Nephew; in an amount of less than USD 10,000 from Orthalign Inc; and in an amount of USD 10,000 to USD 100,000 from Medical Device Business Services Inc. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request. Clinical Orthopaedics and Related Research® neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA approval status, of any drug or device before clinical use. Ethical approval for this study was obtained from the Scripps Institutional Review Board,