OBJECTIVE: Chronic obstructive pulmonary disease (COPD) accounts for about 10 % of patient visits to a neumologist, 7 % of all hospital admissions, and 35 % of permanent work disability. The aim of this study has been to assess health care resources utilization in Spain depending on the severity of the disease. METHODS: This analysis has been carried out through the design of a one-year retrospective naturalistic study performed through the whole Spanish territory, including both urban and rural areas. There have been included 9,045 COPD patients with a mean age of 67 ± 9.8 years. The severity of the disease was as follows: 33.8 % mild (FEV1: 60-80 % of predicted), 49.3 % moderate (FEV1: 40-60 % of predicted) and 16.8 % severe (FEV1 < 40 % of predicted). Health care resources collected were: added visits to the general practitioner (GP) and pneumologist, added visits to the emergency room, length of stay in the hospital and number of days off work. RESULTS: Severe COPD patients presented more added visits to the GP compared to moderate and mild COPD patients (5.83, 4.65 and 3.25 respectively, p<0.001), likewise with regard to added visits to the pneumologist (1.55, 1.09 and 0.62 respectively, p<0.001) and added visits to the emergency room (2.50, 1.62 and 0.9 respectively, p<0.001). In addition, severe COPD patients showed a longer length of stay in the hospital than moderate and mild COPD patients (16.7 vs 10.9 and 8.8 days respectively, p<0.001) and less days off work (51.2, 29.4 and 18.9 respectively, p<0.01). CONCLUSIONS: Severe COPD patients require higher healthcare resources utilization than moderate and mild patients. Therefore, it is necessary to elaborate programs and policies focused in diagnosing early COPD patients to try to avoid progression of mild patients to moderate and severe stages of the disease.