In this paper, the application of a robust multivariable control system designed for a horizontal variable speed wind turbine is discussed. The control problem presented and the background of the design method is given. A H∞ controller based of a linear model that reduces the mechanical fatigue of the turbine is designed. The alleviation of the mechanical loads could increase the lifespan and the quality of the produced energy. The H∞ theory is used to synthesize controllers achieving robust performance and stabilization and it has the main advantage that it does not make any assumptions about the noise and external disturbances that affect the system and it minimizes the worst case estimation error. The performances obtained through this control method are discussed and presented by means of a set of simulations.