Through the use of gait analysis, this study attempts to characterize gait after total knee arthroplasty as a function of postoperative time to quantify the effectiveness of the surgery and to evaluate prostheses of several different designs. Gait analysis on 32 preoperative and 50 postoperative patients included measurement of velocity, cadence, stride length, and gait cycle. Postoperative data were collected at various intervals from 0.7 to 111 months after knee surgery (average postoperative time, 45.3 months). Linear regression analysis of velocity, cadence, stride length, gait cycle, and the ratio of contralateral to pathologic single limb support time as a function of postoperative time are reported with statistical error limits. Extrapolation of these results to zero postoperative time indicates that the patients who had had total knee arthroplasty had a slight improvement in all gait parameters compared to the preoperative control group. This was not statistically significant, however, except for cadence (P <.05). Although velocity and stride length increased slightly toward more normal values with increased postoperative time, gait parameters at no time approached normal values.