Objectives: Spirometry is known to be a gold standard for the diagnosis of chronic obstructive pulmonary disease (COPD). COPD Assessment Test (CAT) is an eight-item questionnaire currently in use to evaluate patients with COPD. In the present study, we aimed to evaluate if CAT is an adequate tool for screening COPD. Methods: In total, 600 persons aging. 40 years old were randomly selected from three different family practice units located in the city center. CATwas asked to the participants and a spirometry was used to assess pulmonary obstruction. Pulmonary obstruction was defined as forced expiratory volume in first second/ forced vital capacity (FEV1/ FVC)< 70% and then COPD diagnosiswas confirmed with the reversibility test. The relationship between CAT results and pulmonary function test values was evaluated. Results: In this sampling, the prevalence of COPD was 4.2%. Reliability of the CAT in the study group was acceptable (Cronbach's a: 0.84). TheCAT scores was significantly higher in patients with COPD (P< 0.001). There was a significant negative correlation between CAT score and FEV1, FVC and FEV1/ FVC ratio (r = -0.31, P< 0.001; r = -0.26, P< 0.001; r = 0.18, P = 0.001). Among smokers, phlegm was the predominating symptom (P = 0.01). Sensitivity of CAT was 66.67% and its specificity was 75.15% to determine COPD. Conclusions: CAT is a reliable questionnaire and there is an apparent relationship between the total CAT scores and COPD. However, CAT's ability to screen COPD is limited since it may miss the symptom-free cases.