OBJECTIVE: Individuals with serious mental illness have elevated smoking rates, and smoking is a significant risk factor for chronic obstructive pulmonary disease (COPD). The goal was to determine the prevalence of COPD among those with serious mental illness. METHOD: The authors surveyed a random sample of 200 adults with serious mental illness with questions from the National Health and Nutrition Examination Study III that were previously used to estimate the national prevalence of COPD. They compared the prevalence of COPD in the sample to a randomly selected matched subset of national comparison subjects. RESULTS: The prevalence of COPD was 22.6%. Those with serious mental illness were significantly more likely to have chronic bronchitis (19.5% versus 6.1%) and emphysema (7.9% versus 1.5%) than the comparison subjects. CONCLUSIONS: The prevalence of COPD is significantly higher among those with serious mental illness than comparison subjects. Improved primary and secondary prevention is warranted.