Patients with medical comorbidities that necessitate chronic anticoagulation therapy frequently present as candidates for total knee arthroplasty (TKA). We asked whether it was necessary to stop warfarin preoperatively to avoid postoperative bleeding complications. We retrospectively reviewed 77 preoperatively anticoagulated patients undergoing TKA. Thirty-eight of these 77 patients were maintained on their routine therapeutic warfarin regimen throughout the perioperative period. The remaining 39 patients had their routine preoperative warfarin regimen discontinued preoperatively and then restarted after surgery. We compared rates of comorbid illness, blood transfusions, wound complications, and reoperations. The demographic data and the ratio of primary to revision arthroplasties were similar in the two groups. The age-adjusted risk ratios for blood transfusions, wound complications, and reoperations were 0.61, 0.29, and 0.43, respectively. The data presented suggest maintaining a therapeutic warfarin regimen throughout the perioperative period for high-risk patients is not associated with an increase risk of complications after TKA. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.