Abstract: Sliding doors, particularly for railway and tramway vehicles, comprise two opposing doors which are movable relative to a doorway between an emplaced closed position and a withdrawn open position by guide means and motorized drive means. The drive means include a motorized chain transmission connected to the two doors to effect their opening and closing sliding movements, and rotatable cam means defining, for each door, an arcuate track with which feeler means connected to the two doors cooperate to effect, in the initial phase of the opening sliding movement and in the final phase of the closing sliding movement of these doors respectively, the withdrawal and the emplacement of the doors relative to the doorway.