OBJECTIVES: Data on prevalence, treatment, and stages of COPD for Germany are limited. This study aims at investigating into prevalence and treatment of COPD as well as the distribution of COPD stages, frequency of comorbidity, and exacerbations. METHODS: Claims data from a German sickness fund were used to perform a retrospective cohort study. For the period of 2001 to 2003 beneficiaries 45 years of age or older were identified as COPD patients if they had a diagnosis of emphysema and/or other chronic obstructive pulmonary diseases (ICD-10 codes J43*, J44*) and/or at least one prescription for a drug for obstructive airway diseases (ATC R03A*). Comorbidity and exacerbations were identified according to related diagnoses and prescriptions. Patients were allocated to COPD stages by detection of drug prescription patterns as defined by the GOLD guideline (Pauwels et al., Am J Respir Crit Care Med 2001;163: 1256-76). RESULTS: Among 499,550 beneficiaries 45 years of age or older 41,100 were identified as COPD patients corresponding to a three-year prevalence rate of 8.2%, with rates of 8.5% in men and 7.9% in women, respectively. Prevalence rates of 9.3% in total, 9.6% in men, and 9.3% in women, respectively, were estimated for the German resident population 45 years of age or older. For many of the COPD patients only few specific drug prescriptions were detected within the three-year observation period. Sixty-eight percent of patients were allocated to GOLD stages 0 and 1 (at risk or mild COPD). Exacerbations were found in 14,513 (35.4%), and comorbidity (mostly cardiovascular disease) in 63% of patients. CONCLUSION: The observed COPD prevalence rates are within the range of results reported in former studies. The low level of treatment with COPD-related drugs may be an indicator for a low awareness of COPD among patients as well as among physicians.