A vibration compensation system for actively attenuating the vibration of a machine. The machine has a housing, with respect to which vibration is to be damped, and at least one body moving within the housing. The vibration compensation system includes a countermass capable of being linearly reciprocated relative to the housing in a direction parallel to the motion of the moving body within the machine. A motor, coupled to the housing, drives the countermass. Elements are provided for sensing the position, or any time derivative or time integral thereof, relative to the housing of the moving body and the countermass. control elements supply power to the motor in response to the signal outputs from all of the sensors so that the acceleration of the countermass is in a direction opposite the acceleration of the moving body. The magnitude of the acceleration of the countermass is equal to the product of the acceleration of the moving body multiplied by its mass divided by the mass of the countermass.