Abstract: A mounting and guiding device for adjustable motor vehicle seats comprises longitudinal C-section guides in which omega (.OMEGA.)-section movable guides are slidable. The beams formed by the guides enclose a rack which is formed by a sheet metal strip fitted centrally of the C-section guide and is provided with slots. The seat frame is articulated by uprights onto brackets which are fitted to the front of the guides, and is locked by pins fixed at the rear of the guides. The device has an operating mechanism which comprises bolts engageable in the slots of the racks through the openings in the guides, and is articulated between brackets which are fixed to the rear of the movable guides. The racks are covered and the space beneath the seat is unobstructed to serve as a storage space if required.