This study addresses the problem of periodic load mitigation of three-bladed horizontal-axis wind turbines. In periodic load reduction, individual pitch control (IPC) has proved to be effective by means of controllers with an internal model that takes into account the periodic signal frequency. However, the frequency components on the blades vary with the rotor speed of the wind turbine and the above controllers reduce their mitigation performance. This paper proposes a new IPC scheme to mitigate the main frequency components of the periodic disturbances affecting the rotor and structure of wind turbines. The IPC scheme is based on the active disturbance rejection (ADR) philosophy and is formulated in spatial-domain instead of time-domain. The spatial-domain formulation of the controller assures that the disturbance rejection performance is not affected by changes of the rotor speed. A 5 MW reference wind turbine implemented in the FAST (fatigue, aerodynamics, structures and turbulence) code is used for the validation. The results show effective attenuation of the periodic load components of the blades using the proposed ADR scheme.