Sliding door for motor vehicles, having an outer door skin, an inner door skin and a door inside trim, supported on a guide rail on a vehicle body and movable between opened and closed positions. The sliding door includes a cable guide assembly for accommodating and guiding electric cables, which connect first electric elements provided in or on the vehicle body to second electric elements provided on the sliding door, whereby on moving the sliding door, the cable guide assembly is movable in a plane including the longitudinal direction of the vehicle and whereby a guide channel for guiding the cable guide assembly is provided on moving the sliding door. Guide surfaces of the guide channel are formed or integrated at least in sections on the inner door skin, in a door module support and/or on the door inside trim.