Fifty-two patients undergoing total knee arthroplasty (TKA) were randomized to receive surgery with a kinematic computer navigation system or with the conventional method. The purpose was two compare the two groups for mechanical axis of the leg postoperatively. At 3 months, significantly more patients in the computer navigated group demonstrated a straight axis in the mechanical alignment of the leg than the conventional group. However, the computer navigated technique required a significantly longer operation and tourniquet time than the conventional method. There was no significant difference between the two groups for any other clinical, radiographic, or intraoperative outcomes.