OBJECTIVE: This study estimates inpatient, outpatient, and prescription drugs expenditures and health care utilization for patients with Chronic Obstructive Pulmonary Disease (COPD). METHODS: Inpatient and outpatient claims with primary diagnosis of COPD-defining diseases (ICD-9 codes 491**, 492**, 496**) from 1998-2002 were extracted from Medstat Marketscan database and then matched to prescription drug expenditures using unique identifiers. Regression models controlled for age, gender, employment status, health plan type and other variables. All regression factors mentioned below were significant with p <0.01. RESULTS: Average per patient annual expenditures was $7874-$11,412 for inpatient service depending on the type of health plan; $154-$238 for outpatient visits; and $85-$151 for prescription drugs. Results also indicated that gender, age, health care plan type, the region where patient lived and the patient's industry type all significantly affected health care expenditures and utilization for COPD care. For example, women were less likely to be hospitalized or receive outpatient care, but were more likely to fill COPD-related prescription drugs. Patients in plans requiring a primary care physician referral to receive specialty care (PCP plans) were less likely to be hospitalized, made fewer outpatient visits and filled fewer COPD-related prescriptions. Overall, inpatient expenditures were 1.2% higher for men and 18% lower for patients enrolled in PCP plans. Outpatient expenditures were about 3% higher for men and about 1.7% higher for patients in PCP plans. Prescription medication expenditures were about 2% higher for men and about 19% lower for patients in PCP plans. In all regressions, older patients had higher expenditures. CONCLUSION: There is a substantial economic burden associated with COPD which can potentially be reduced significantly by enrolling patient in PCP plans. Further research is needed to examine why men with COPD use more health care than women and to assess the quality of care provided by PCP plans.