An open-loop adaptive control strategy for synchronous vibration control is described. The ability of active feed back control of vibration in a flexible rotor-bearing system is discussed and it is shown that active control can substantially reduce vibration level in rotating machinery. The control strategy for optimization of the response of a flexible rotor-bearing system subjected to a step change in imbalance is then analyzed. Implementation of a local feedback control strategy for the active control of vibrations caused by a sudden change in imbalance in a flexible rotor-bearing system with an electromagnetic actuator is discussed. Finally it is shown how an open-loop adaptive control strategy can be combined with a local feedback control strategy to minimize the synchronous vibration and also contain any build-up of dangerously large amplitude of vibration in case of a step change in mass imbalance in a flexible rotor-bearing system.