Abstract: An improved guide rail arrangement especially adaptable for vehicle power seats includes a pair of interleavable guide rail assemblies that are individually bolted to the vehicle seat and to the vehicle floor. The fixed guide rail assembly includes a C-shaped member extending upwardly into a guiding space that is formed between the parallel, downwardly projecting legs of a pair of U-shaped rail elements forming the movable rail assembly. A plurality of spaced, horizontally disposed alignable apertures are respectively incorporated in adjacent legs on one transverse side of the interleaved guide rail assemblies. Horizontal movement of the movable rail assembly with respect to the stationary assembly is stopped in a novel way by incorporating a pair of blocking plates symmetrically supported on transversely opposite sides of the longitudinal axis of rail movement.