Pain is one of the most common causes of disability and work loss. However, patients with chronic pain have not been regarded as impaired persons in the Republic of Korea because of a lack of objective findings in those patients and difficulties in validating their genuine suffering and quantitative evaluation of pain. Here, the difficulties in the evaluation of impairment in chronic pain patients are discussed. In addition, guidelines for rating impairment in chronic pain patients, which are under development by the Korean Academy of Medical Sciences, are introduced.(Korean J Pain 2007; 20: 1-7)