This publication provides guidelines for evaluating the engineering safety aspects of the protection of nuclear power plants against sabotage. The guidance, which is the result of extensive dialogue among safety and security specialists, takes into account the existing robustness of structures, systems and components and emphasizes those aspects of sabotage protection that work synergistically with the protection against extreme external occurrences of accidental origin, such as earthquakes, tornadoes and human induced events. The report introduces a defence in depth approach to sabotage protection, with layers comprising safety and security related systems and activities, and promotes self-assessment by the licensee in cooperation with the competent authorities.