The Burden of Obstructive Lung Disease (BOLD) initiative provides a standardized way of measuring the prevalence of COPD. We used the BOLD survey to estimate the prevalence of COPD in adults aged >or= 40 years in a target population of 325,000 in Southeastern Kentucky. Testing was done at survey centers and homes and included questionnaires on respiratory symptoms, risk factors for COPD, and health status. Postbronchodilator spirometry was used to classify subjects. We determined the prevalence of COPD along with the relation of COPD and comorbid disease and physical and mental quality of life measures. The final study population was 508, with a participation response rate of 25.2%. Overall, 19.6% of subjects met criteria for Global Initiative for Chronic Obstructive Lung Disease stage 1 or higher COPD, and an additional 17.6% met criteria for restriction. Diabetes, heart disease, and hypertension were significantly increased in subjects with restriction. Physical quality of life was significantly decreased in all respiratory impairment categories, compared to normal subjects, whereas mental quality of life measures were not affected. In this population, respiratory impairment is highly prevalent and associated with comorbid disease and physical, but not mental, dysfunction.