From recordings of reaction forces on the feet in the vertical (z) and horizontal for-aft (x) direction during walking, x-z vector-diagrams (VDG) are constructed for the purpose of clinical use in the evaluation of gait. Such use presupposes the existence of reference values. The parameters of VDG, ie, the maximal coordinates of the vectors, are dependent on weight, speed of walking, age, step length, and physical condition. A requirement of studies on reference values is that these variables as well as height are accounted for. VDG were applied to evaluation of gait of hemiplegic subjects: slow speeds, alterations in the functions of the limbs and irregularities due to instability were noted.