Field potentials evoked in the accessory olfactory bulb (AOB) of the mouse by a vomeronasal organ (VNO) volley were analyzed with current source-density (CSD) techniques. The potentials were recorded with an electrode oriented in the direction perpendicular to the laminae of the centre of the AOB in five tracks of equal spatial lattice for identical coordinates. There were little or no differences in the amplitude or time course of the potentials at equal depth among the five tracks. The CSD profile from a one-dimensional CSD analysis corresponded closely with that of a three-dimensional CSD analysis of a central track in the AOB. Furthermore, VNO-evoked field potentials were recorded in the AOB external plexiform layer while an electrode was being moved in the direction parallel to this layer. The potentials recorded at adjacent points were nearly identical and hence the related one-dimensional CSD calculations revealed no net currents along this layer. These results indicate that a one-dimensional CSD analysis is applicable to the mouse AOB.