Chronic obstructive pulmonary disease (COPD) is a costly cause of morbidity and mortality in the U.S. The objective of this study was to use contemporary national data-specifically, those from the 2000 Medical Expenditure Panel Survey (MEPS)-to estimate direct costs of COPD in the U.S. from an all-payer perspective. Due to constraints of MEPS data, indirect costs were excluded from our analyses, as were costs of long-term oxygen therapy and costs from nursing homes and long-term care facilities. Two methods of cost estimation were employed. First, we estimated resources used and expenditures incurred by individuals with COPD that were directly attributable to the disease (attributable cost approach). Second, we compared overall medical expenditures of patients with COPD to those of the non-COPD population; the resulting difference represented excess costs of COPD. Approximately 1.7% (n = 144) of the nearly 8,300 persons in the analysis data set aged > or = 45 years used medical resources and incurred expenditures related to treatment of COPD. Mean attributable costs per patient were estimated at dollar 2,507, with more than one-half of these costs (dollar 1,365) associated with hospitalization. Mean excess costs of COPD, after adjustment for sociodemographic factors and smoking status, were substantially higher, at dollar 4,932 per patient. Results of our study indicate that COPD-associated healthcare utilization and expenditures are considerable, and that annual per-patient costs of COPD are comparable to those of other chronic diseases of the middle-aged and elderly.