OBJECTIVES: Chronic Obstructive Pulmonary Disease (COPD) currently represents the fifth leading cause of death worldwide and it’s estimated to rise to the third cause by 2030. Few studies have estimated the burden of COPD. The aim of this study was to evaluate consumption and cost of health care resources of severe COPD patients in the general population from the Italian health care system perspective. METHODS: Data were extracted from Healthcare Administrative Databases (HADs) of the region of Lombardy, which covers a population of 9.2 million members. HADs related to eligibility criteria, hospital admissions, pharmaceutical and outpatient claims have been organized in a data warehouse using probabilistic record linkage. The study included subjects aged more than 18 years that in 2003 had at least one hospitalization with COPD as the main diagnosis or as the second one when the main was: pneumonia, respiratory or heart failure, pneumothorax and acute pulmonary heart disease. Subjects were followed for two years collecting information on healthcare resource and vital status. Severe and moderate exacerbations of COPD were respectively defined as hospitalizations for COPD and as prescriptions of corticosteroids and/or antibiotics after the index hospitalization.  RESULTS: We selected 16,476 patients with age mean 76 years and an average follow-up of 19 months. The 38% of patients were women with mean age three years higher than men. Subjects with severe exacerbations had on average 4.4 moderate and 1.9 severe episodes after the index hospitalization. The mean annual cost for these patients was €11,824 (IC95% 11,554 – 12,079). Patients with only moderate exacerbations had on average 3.9 moderate exacerbations and the mean annual cost was €6413 (IC95% 6288 – 6549). Costs were steady in time. CONCLUSIONS: The burden of COPD is important both in frequency and cost; it requires an effort in programming new health services particularly devoted to aging population.