A system for guiding and supporting a leaf of a platform-access door capable of moving relative to a fixed panel in a horizontal translational movement in a plane of the leaf between open and closed positions, includes a rail extending in a direction of the horizontal translational movement, a first set of rollers collaborating with the rail with and being made up of: a main roller in contact with a lower bearing surface of the rail; first and second secondary rollers which are vertically offset from one another and are respectively in contact with the lower bearing surface and with an upper bearing surface of the rail and are spaced from the main roller.