BackgroundThe Duke Activity Status Index (DASI) assesses the functional capacity of patients with cardiovascular disease (CVD), but there is no Portuguese version validated for CVD. ObjectivesTo translate and adapt cross-culturally the DASI for the Portuguese-Brazil language, and to verify its psychometric properties in the assessment of functional capacity of patients with CVD. MethodsThe DASI was translated into Portuguese, then checked by back-translation into English and evaluated by an expert committee. The pre-test version was first evaluated in 30 subjects. The psychometric properties and correlation with exercise testing was performed in a second group of 67 subjects. An exploratory factor analyses was performed in all 97 subjects to verify the construct validity of the DASI. ResultsThe intraclass correlation coefficient for test-retest reliability was 0.87 and for the inter-rater reliability was 0.84. Cronbach's α for internal consistency was 0.93. The concurrent validity was verified by significant positive correlations of DASI scores with the VO2max (r = 0.51, p < 0.001). The factor analysis yielded two factors, which explained 54% of the total variance, with factor 1 accounting for 40% of the variance. Application of the DASI required between one and three and a half minutes per patient. ConclusionsThe Brazilian version of the DASI appears to be a valid, reliable, fast and easy to administer tool to assess functional capacity among patients with CVD.