In a loading platform system for mounting on vehicles, particularly trucks, comprising at least one lift support arrangement consisting of two essentially parallel spaced support structures, an essentially plate-like loading platform for lifting and lowering a load, at least one lift actuator for lifting and lowering the loading platform and a slide unit, which is movable back and forth in the longitudinal direction of the vehicle and mountable on the vehicle and on which at least the lift support arrangement, the loading platform and the lift actuator are mounted. The slide unit is adapted to be mounted on the support frame of the vehicle by transverse frame members, which are fitted to the spacing of the vehicle support frame members and include means at their ends for mounting them to the vehicle support frame members.