The authors of this review are members of the Aberdeen Pain Group, a group of multidisciplinary researchers who have been researching chronic pain for over 10 years. This review draws upon their experience to consider the measurement of chronic pain severity from a research perspective. The first half summarizes the requirements of a measure of pain severity for epidemiological research, describes a number of existing measures of pain severity and discusses the appropriateness of these instruments for measuring chronic pain as part of a postal epidemiological survey. The second half focuses on the use of the Chronic Pain Grade questionnaire by the Aberdeen Pain Group. The reliability and validity of this instrument as part of a postal questionnaire, its sensitivity to change over time, and how the use of such an instrument compares with retrospective perceptions of patients are all investigated. The review concludes with a brief discussion of future issues relating to the measurement of chronic pain severity, again from a research perspective.