Abstract: A shock absorber for vehicles with pneumatic suspension, particularly for use with heavy vehicles, of the type comprising a cylinder, a rod movable axially in the cylinder, a piston carried by the rod and dividing the cylinder into a cylindrical chamber and an annular chamber, a pressurized fluid filling the cylindrical and annular chambers, a first circuit for allowing the fluid to flow from the annular chamber to the cylindrical chamber when the shock absorber is working under extension, a second circuit for allowing the fluid to flow from the cylindrical chamber to the annular chamber when the shock absorber is working under compression, a pressurized fluid reservoir connectable to the cylindrical and annular chambers and flow regulators mounted in the first and second circuits, the flow regulators being controlled by the fluid pressure against the action of the pressure of the compressed air of the pneumatic suspension of the vehicle.