BACKGROUND: Valid assessments of health-related Quality of Life (HRQL) are increasingly important in chronic, incurable conditions, such as chronic heart failure (CHF). AIMS: To evaluate the psychometric properties of a Swedish version of the Kansas City Cardiomyopathy Questionnaire (KCCQ) in hospitalized patients with decompensated CHF. METHOD AND RESULTS: The KCCQ and SF-36 were administered to patients (n=118) with CHF at baseline and then 1 (n=51) and 4 months (n=83) after admission. The Swedish version of the KCCQ appears to have acceptable convergent and discriminant validity for all suggested health domains. Cronbach's alpha and test-retest reliability met for most of the scales the minimum of 0.70. Known-groups comparison indicated that the KCCQ discriminated between patients differing in the New York Heart Association (NYHA) classification (criterion validity). The KCCQ was also more responsive to changes in the NYHA classification as compared with the SF-36. However, KCCQ has some weakness in the response distributions for two questions and the convergent validity in one question. CONCLUSION: Overall, the KCCQ is a valid and reliable instrument in a Swedish CHF population. It yields reliable and valid scores and is quite responsive to clinical change.