Objective: To evaluate the risk and efficacy of simultaneous bilateral total knee arthroplasty(TKA) in treatment of osteoarthritis when compared with sequential bilateral TKA and unilateral TKA. Methods:A retrospective analysis was performed on 162 patients who underwent TKA from 2003 to 2006. The analyses were adjusted for demographics, preexisting medical conditions, and osteoarthritis diagnosis. Results:Patients undergoing simultaneous bilateral TKA had significantly lower amounts of blood loss, shorter surgical time, shorter hospitalization time, less hospital charges and lower rates of perioperative complications compared with patients undergoing sequential bilateral TKA. No significant difference was found with regard to postoperative complications between the simultaneous bilateral and the unilateral TKA groups. Patient’s knee range of motion and the postoperative Hospital for Special Surgery scores(HSS) were similar for the three groups. Conclusion:When there are adequate indications for bilateral TKA, simultaneous bilateral TKA is beneficial to patients compared with sequential bilateral or unilateral TKA.