Abstract: Objective To examine the prevalence and risk factors of chronic obstructive pulmonary disease(COPD) in the residents of urban Chongqing and to propose measures of early prevention and therapy.Methods A cross-sectional study on COPD was carried out from December 2007 to January 2008.Urban populations were randomly selected from Nanhu and Yuhua community in Nan'an district of Chongqing with cluster sampling.A total of 2 133 residents aged 40 years or older were interviewed with a questionnaire revised from the international Burden of Obstructive Lung Diseases(BOLD) study.Spirometry was performed on all eligible participants.Results Among the interviewees,2 024 completed the questionnaire and spirometry.The overall prevalence in COPD was 7.9%(160/2 024); the prevalence in the males was 15.5%(123/792) and that in the the females was 3.0%(37/1 232).The COPD prevalence in the smokers was 15.9%(118/743) and 73.8% of the(118/160) COPD patients had smoking history.Multivariate logistic regression analyses showed that male,elderly age,lower body mass index,smoking,with higher smoking index,frequent cough before 14 years old,and poor ventilation in the kitchen when coal and/or biomass feuls were used in the house for cooking were important risk factors of COPD,with the odds ratios of > 1(P < 0.01 for all).Only 58.8% of COPD patients were diagnosed with emphysema,asthma,and chronic bronchitis or COPD and 24.4% of the COPD patients were examined by spirometry and 23.1% of COPD patients had no symptoms.Conclusion COPD was high prevalent in urban Chongqing and there were missed diagnosis for COPD patients with a lowspirometry examination rate.Smoking is one of the most important risk factors for COPD.