A vehicle seat backrest suitable for allowing the attachment of a child seat, the backrest comprising a rigid structure and an anchoring system comprising an anchor rod to permit to a coupling member belonging to the child seat to be anchored on the anchor rod via the rear face of the rigid structure. The anchoring system comprises a rigid plate comprising retainer suitable for retaining the anchor rod by abutment contact when the coupling member of the child seat exerts forces on the said anchor rod.

The structure of the seat proper of a vehicle seat comprises: a frame for a seat proper, the frame including a side cheek plate; and a coupling system comprising a link mounted to pivot on a base to enable the seat proper to move at least vertically relative to said base. The coupling system has a first latch surface.The seat structure further comprises an anchoring element provided with a second latch surface.The anchoring element is mounted to move on the cheek plate between a locked position and an unlocked position.