The invention relates to an electro-hydraulic actuator, especially for an antilock brake system, which directly converts electrical input energy into hydraulic useful energy and has an especially simple and problem-free design as well as very rapid adjustability. A working chamber of the actuator according to the invention is filled with an electrostrictive fluid and provided with an electrically controlled electrode system to generate an electrical field that causes a change in pressure and/or volume in the electrostrictive fluid.