This study includes laboratory measurements using different models in order to determine the effect of wall-phenomenon on the electrical resistivity measurements, and field applications. This phenomenon had been studied in the case of homogeneous medium of which the resistivity is constant, and in the case of unhomogeneous medium, composed of two or three different layers. It is found that the effect of this phenomenon is the same although the medium resistivity is different or with the increase of the number of layers. This phenomenon changes according to the measurements conditions such as the measurements direction concerning the edge of slope or wall, the distance between AB electrodes, and the distance between the configuration and the wall.