To review the psychometric validation of the Chronic Venous dIsease quality of life Questionnaire (CIVIQ-20) in the countries that have used it since 1996. Prospective, clinical, international study in 18 countries. Patients with venous disease of the lower limb in the clinical, aetiological, anatomical and pathophysiological (CEAP) clinical stages C0s to C4 presenting to surgical outpatient departments and general practices and receiving drug treatment for 6 months. Quantification of symptoms on a four-point scale and pain on a visual analogue scale, and self-administration of CIVIQ-20 to patients before visit (baseline, 2, 4 and 6 months). In 3956 patients, CIVIQ-20 showed good internal consistency and reliability (above 0.80) through test-retest correlations. The discriminating power of items was good in known groups of patients. Factor analysis identified physical, psychological and pain factors as important, but revealed instability of the social factor. CIVIQ-20 was highly sensitive to changes in the quality of life of patients clinically improved after drug treatment. CIVIQ-20 is valuable in assessing treatment effects in longitudinal, multinational studies, but comparisons of different populations should use the global score rather than scores per dimension. Copyright © 2010 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.