OBJECTIVES: To assess the relationship between the  questionary of quality of life “COPD assessment test” (CAT) and clinical, functional and comorbidity parameters and compare patient perceptions of symptoms with that of their family members. METHODS: We analysed demographic (age, sex, BMI), lung function (FEV1%) and comorbidity variables (Charlson index) in patients with stable COPD. Patients and family members independently completed the CAT (family members reported their observations of the patient). RESULTS: We included 70 patients (83% men, mean age 72±9.4 years, BMI 27.8±4.2 kg/m2, Charlson index (ChI) 2.41±1.7, mean FEV1% 57.1±15.1%. Air flow limitation (GOLD): 7 patients (9%) mild, 36 (53%) moderate, 24 (34%) severe and 3 (4%) very severe. There was a significant negative correlation between CAT and FEV1% (r=-0.265, p<0.0028) but no correlation between CAT and ChI, age or BMI. A comparison of CAT scores between the patients and their family members showed that 61% of the patients underestimated and 33% overestimated their symptoms (CAT scores: 15.5±7.9 (patient) vs. 17.1±7.7 (family) (p<0.038); correlation: (r=0.72; p<0.001). We observed correlations in the 8 CAT items. We found significant differences between the patients and their family members in items 1: coughing (p<0.015), 3: chest tightness (p<0.005) and 6: confidence leaving home (p<0,015) and in overall score (p<0.038). CONCLUSIONS: 1. We found a negative correlation between the CAT and FEV1but not between the CAT and Charlson index. 2. Patients underestimate their symptoms. Cough, chest tightness and confidence leaving home are the issues items that had the greatest discrepancy between patients and family members.