Assessing the prevalence of COPD requires spirometry, as clinical findings alone are insufficient for diagnosis. Consequently, available data are limited: the widespread use of spirometers is challenging due to a lack of not so much the equipment itself but rather the availability of trained and experienced investigators. Another challenge is the definition of bronchial obstruction, which varies from one study to another. Finally, there are few equations available for calculating normal spirometry values in older adults, and these likely need to be updated. Despite these limitations, international and French data converge on a COPD prevalence of 4–10%, with approximately half of patients having a still-normal FEV1 (Stage I), more than one-third having Stage II COPD (FEV1 between 50% and 80% of normal), and less than one-quarter having Stage III-IV COPD (FEV1 <50%). The prevalence of chronic bronchitis is similar, but it is not an independent predictor of bronchial obstruction. Several ongoing studies in France will certainly help refine these data.