To validate a Portuguese-language version of the COPD assessment test (CAT) for use in Brazil and to assess the reproducibility of this version. METHODS: This was multicenter study involving patients with stable COPD at two teaching hospitals in the city of Fortaleza, Brazil.... Patients were asked to fill in COPD assessment test (CAT) and Clinical COPD Questionnaire (CCQ) quality-of-life questionnaires in their validated versions in Spanish. The patients were evaluated again after 4 to 6 weeks from the initial visit, at which point they filled out both questionnaires once more.