The invention relates to a trailer coupling for motor vehicles, comprising a coupling ball carrier which can be mounted on a vehicle body and a coupling ball with a ball body which has a ball surface extending between a ball attachment and an upper end surface of the ball body, with which the ball surface comprises a sensor zone for recognizing a body located close to or on the coupling ball, several detection locations different from one another are located in the sensor zone, a sensor unit arranged stationarily in the ball body beneath the ball surface is associated with each detection location and each sensor unit is designed such that it detects a body present in a close-proximity area above the ball surface at the respective detection location.