A folding rear seat for vehicles, especially passenger vehicles and station wagons, includes a folding seat back and a height-adjustable neck support mounted on the seat back. The neck support is mounted on at least one support rod that supports a padded head rest and is held such that it can shift axially within a guide in the seat back. The head rest can be retracted from a temporary vertical position to a minimum possible distance between the padded head rest and the seat back in order to allow the seat back to be folded down. To ensure that the seat back can be folded down completely without removal of the neck support, and to ensure the automatic return of the neck support to a legally prescribed minimum vertical position for the padded head rest, the guide mechanism is formed by at least one guide sleeve that holds the support rod such that it can shift axially, and a spring element is positioned between the guide sleeve and the support rod, such that the spring is first tensed by the support rod when the vertical position of the neck support is reduced from the prescribed minimum vertical position for the padded head rest to the minimum possible distance, by force of pressure.