A guide piece, for connecting the fixing region of a guide rail to the door frame of a vehicle door, whereby the guide piece may be fixed in the external skin thereof, houses a fixing means and the fixing region of the guide rail which may be adjusted in the direction of the vehicle transverse axis (Y-axis) within the guide piece. The guide piece with fixing clips in slots in the external skin can be adjusted in the direction of the vehicle longitudinal axis (X-axis) as required, relative to the external skin of the door frame and may be pre-positioned on the fixing region of the guide rail with a positive fit. The guide piece is embodied in two pieces and comprises a cover which may be connected to a baseplate, between which a part of the fixing means is positively fitted and a part of the fixing region of the guide rail is adjustably arranged perpendicular to the plane of the vehicle door (Y-axis).