INTRODUCTION: COPD is a leading cause of death worldwide; however, prevalence estimates have varied considerably in previous studies. This study aimed to determine the prevalence and severity of COPD in Copenhagen using data from the 4th examination of The Copenhagen City Heart Study, to investigate the relationship between tobacco consumption and COPD, and to characterize the subjects with COPD with regard to BMI, dyspnoea, treatment with respiratory medication and co-morbidities. METHODS: 6236 people participated. All non-asthmatic participants aged 35 years or older with adequate lung function data were included for the final prevalence analyses (n = 5,299). COPD staging was done according to the GOLD criteria. RESULTS: The overall prevalence of COPD was 17.4%. The prevalence increased with age and was higher among males. 6.2% had mild COPD, 9.2% had moderate COPD, and 2.0% had severe or very severe COPD. Tobacco consumption was closely linked to both prevalence and disease severity. Subjects with COPD had lower mean Body Mass Index (BMI) and more frequently a BMI < 21 kg/m(2). Dyspnoea was correlated to lung function but a substantial number of participants with severe COPD experienced no dyspnoea. Only a minority of subjects with COPD received pulmonary medication. COPD was associated with cardiovascular disease and cancer. CONCLUSION: The prevalence of COPD in Denmark is among the highest in the world. It is closely correlated to smoking and age. It is accompanied by substantial co-morbidity and it is grossly under treated.