Wind turbine stabilization

System for stabilizing an offshore horizontal axis wind turbine having a tower (10), the system comprising sensors for generating signals representing detected movements of the tower, and gyroscopes (23). Each gyroscope has a spinning axis (17), an input axis (18) and an output axis (19), and a flywheel (16) rotatable about the spinning axis. The system further comprises an actuator for each gyroscope which can apply a torque about the input axis of the gyroscope. The system also comprises a control unit for receiving the signals representing detected movements of the tower, and for providing the actuator with suitable control signals for said actuator to apply a torque about the related gyroscope input axis, said torque about the input axis producing a torque about the output axis of the same gyroscope that at least partly dampens the detected movements of the tower.