OBJECTIVES: To validate the Spanish version of the health specific questionnaire to evaluate the impact of fatigue on patients with COPD “COPD and asthma fatigue scale (CAFS)" METHODS: Observational, prospective, multicenter study in a sample of patients with moderate/severe COPD. Data were collected at inclusion and at day 15, including the Spanish version of CAFS (12 items, range: 12 best - 60 worst) and the “gold standard” Saint George Respiratory Questionnaire (SGRQ). Additionally, socio-demographics,  clinical data and one item about self-perceived change in health status between visits were recorded. Feasibility, validity, reliability (internal consistency, test-retest) and responsiveness  to change of the CAFS Spanish version were evaluated. RESULTS: A total of 142 patients were included, 87.1% males, mean age (SD) was 67.4 (8.2) years, 52.7% with primary studies, 75% former smokers, FEV1 (%) = 48.5%, (SD= 13.3), 51.3% stage II, 37.6% stage III and 11.1% stage IV. Mean (SD) score in CAFS was 36.7 (12.1). CAFS questionnaire showed low levels of absent information: the mean number of items not responded per patient was <0.1, and no item accumulated more than 1 missing response. Floor and ceiling effects of CAFS (proportion of patients accumulated in the minimum and maximum possible scores, respectively), were low (<2%). CAFS showed satisfactory levels of reliability: high internal consistency (Cronbach’s alpha= 0.88) and excellent test-retest reliability among patients who reported subjective stability in their health status (inter-class correlation coefficient= 0.85). Correlations between CAFS and SGRQ global scores were high (0.79), such as the correlations between CAFS and SGRQ dimensions (0.63 to 0.74). Significant differences (p<0.01) in LCOPD were observed in exacerbated patients who reported an improvement, with a high effect size (0.90).  CONCLUSIONS: According to preliminary results, Spanish version of CAFS showed satisfactory psychometric properties in terms of feasibility, validity, reliability and responsiveness to change.