The prevalence of chronic pain in the general population ranges from 10% to over 40%, depending on the investigation and definition. Chronic pain is tied to high direct and indirect costs for the health care system on the one hand and considerable personal impairment of the quality of life on the other. The present paper provides an overview of the frequency and distribution of chronic pain in the general population and among those receiving treatment. The limitations of epidemiological investigations lie in the difficulty of validly assessing subjective internal experiences of the patients. Moreover, it is not possible to make diagnoses in the proper sense. In contrast,the examination of patients seeking and receiving treatment offers a further diagnostic differentiation and better assessment of the qualitative aspects of the pain experience. However, the meaningfulness of these studies is also limited due to the qualitative problems. Despite the methodological limitations of the studies investigated, the wide distribution and meaning of chronic pain becomes clear particularly when evaluating studies on the general population and populations receiving treatment.