Abstract: The invention relates to a vehicle seat which has a seat portion and a back portion connected at its lower end to the seat portion. The back portion has a frame including two laterally spaced side members which each have two portions, namely an upper portion and a lower portion, which are hingedly connected together about a hinge axis disposed generally at about the knee height of a person sitting behind said seat in another, similar, seat. Each side member of said back portion has an energy absorbing device which is connected between said upper and lower portions of the member so as to be capable of absorbing energy in the event of an impact being applied to the upper portion of said seat back portion by a person thrown forwardly from the rear in a manner such that said upper portion of the back portion turns or tends to turn about said hinge axis relative to said lower portion of the seat back portion.