We have presented the results of an electrogoniometric method of measuring the three planes of knee motion while walking. The results were comparable to those obtained by photometric methods using skeletal pins or skin markers. The electrogoniometric method has the great advantage that it can be used in clinical studies. Knee motion in men and women differed only in the amount of flexion during stance phase. Less flexion occurred in women. Motion in the right and left knees was the same in men as a group but may differ in individuals. The timing of events in the gait cycle differed between individuals but a similar sequence or pattern of motion occurred in all normal knees.