A headrest adjustment assembly is disclosed for adjusting the position of a headrest relative to a seatback. The headrest adjustment assembly includes a guide disposed in the seat back, at least one holding bar disposed within the guide, the guide and holding bar being configured with sufficient clearance to allow selective relative longitudinal and transverse sliding, the holding bar being fixed to the headrest, and a clamping element mounted to the seat back for selectively applying a transverse force to the holding bar to thereby fix the position of the holding bar within the guide and prevent relative transverse or longitudinal sliding.