Damper with a damper chamber and a controllable throttle valve. The damper chamber is split into a first and a second chamber by a movable piston connected to a piston rod. The first chamber is connected to the second chamber via a reflux channel, the throttle valve and a connecting channel. An electronic control device is provided. A magnetic field source controlled by the electronic control device is associated with the throttle valve, in order to apply a magnetic field to a magneto-rheological damping medium flowing through a damping channel of the throttle valve. A compensating chamber with a pre-stressed compensating volume is provided. The compensating volume is connected to the throttle valve and to the second chamber. The throttle valve, the magnetic field source and the compensating chamber are arranged outside of the damper chamber. A one-way circuit in which two one-way valves are fitted is provided for the magneto-rheological damping medium, with the result that the damping medium flows in the same direction of rotation, both when the piston rod plunges into the damping chamber and when the piston rod emerges from the damping medium. At the same time, a first of the one-way valves is arranged at the piston, thereby allowing the damping medium to flow from the second chamber into the first chamber. A second one-way valve is arranged between the throttle valve and the second chamber, thereby allowing the damping medium to flow from the throttle valve into the second chamber.