Abstract: A deceleration responsive vehicle seat (20) for an occupant (9) of a vehicle, wherein the seat has a frame structure adapted to absorb the weight of the occupant and other forces exerted by said occupant on the seat. The frame structure includes a seat cushion frame assembly comprising a seat cushion frame (21), a seat cushion (22) being supported on said seat cushion frame, the frame structure further including a backrest frame assembly (25,27), a backrest cushion having an upper part (26) and a lower part (28), said backrest cushion being supported by said backrest frame assembly. The seat cushion and backrest cushion support the occupant in an upright sitting normal position. The seat further includes frame structure fixation means (2,3) adapted and arranged to fix said frame structure to the vehicle body. The seat further includes an integrated seat belt system (40,41,42,43) for said occupant.