Wind turbine blade misalignments were measured. About 38 % of the turbines measured have been operating outside the accepted misalignment range. This research quantifies the effect of the measured misalignment on the turbine lifetime by means of simulations. The lifetimes of the main frame at the tower top and the tower base were affected most by a blade misalignment. To avoid a lifetime reduction, blade misalignments should be identified and corrected as early as possible during the lifetime.